Answer:
1. The concentration of [tex]NO_2[/tex] is equal to the concentration of [tex]N_2O_4[/tex] : False
2. The rate of the dissociation of [tex]N_2O_4[/tex] is equal to the rate of formation of [tex]N_2O_4[/tex]: True
3. The rate constant for the forward reaction is equal to the rate constant of the reverse reaction: False
4. The concentration of [tex]NO_2[/tex] divided by the concentration of [tex]N_2O_4[/tex] is equal to a constant : False
Explanation:
[tex]N_2O_4(g)\rightleftharpoons 2NO_2(g)[/tex]
The concentrations of reactant and product is constant and not equal.
The rate of forward and backward reactions are equal. Thus rate of the dissociation of [tex]N_2O_4[/tex] is equal to the rate of formation of [tex]N_2O_4[/tex]
For a reversible reaction, the equilibrium constant for the forward reaction is inverse of the equilibrium constant for the backward reaction and not equal.
Equilibrium constant is the ratio of the concentration of products to the concentration of reactants each term raised to its stochiometric coefficients.
[tex]K_c=\frac{[NO_2]^2}{[N_2O_4]}[/tex]
Final answer:
Statements 1 and 3 are False, and 2 and 4 are True. At equilibrium, the rate of formation and dissociation of N₂O₄ are equal but their concentrations are not necessarily the same. Rate constants for forward and reverse reactions are different yet define the equilibrium constant. The concentration ratio of NO₂ to N₂O₄ is constant at a given temperature.
Explanation:
When dinitrogen tetroxide (N₂O₄) is in equilibrium with nitrogen dioxide (NO₂), the following statements can be made:
1. The concentration of NO₂ is equal to the concentration of N₂O₄. False - The stoichiometry of the reaction is 1:2, so for every molecule of N₂O₄ that dissociates, two molecules of NO₂ are formed.2. The rate of the dissociation of N₂O₄ is equal to the rate of formation of N₂O₄. True - At equilibrium, the rate of the forward reaction (dissociation of N₂O₄) is equal to the rate of the reverse reaction (formation of N₂O₄).3. The rate constant for the forward reaction is equal to the rate constant of the reverse reaction. False - The rate constants for the forward and reverse reactions are generally different, but their ratio is constant at a given temperature, defining the equilibrium constant.4. The concentration of NO₂ divided by the concentration of N₂O₄ is equal to a constant. True - At equilibrium, this ratio is equal to the equilibrium constant (Keq) for the reaction at a given temperature.Consider the nitration by electrophilic aromatic substitution of salicylamide to iodosalicylamide. Reaction scheme illustrating the iodination of salicylamide by sodium iodide and sodium hypochlorite via an electrophilic aromatic substitution to form iodo-salicylamide. The density of salicylamide, d = 1.09 g/mL. A reaction was performed in which 3.65 mL of salicylamide was reacted with a mixture of concentrated nitric and sulfuric acids to make 5.33 g of iodosalicylamide. Calculate the theoretical yield and percent yield for this reaction.
Answer: The percent yield of the reaction is 68.68%.
Explanation:
To calculate the mass of salicylamide, we use the equation:
[tex]\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}[/tex]
Density of salicylamide = 1.06 g/mL
Volume of salicylamide = 3.65 mL
Putting values in above equation, we get:
[tex]1.06g/mL=\frac{\text{Mass of salicylamide}}{3.65mL}\\\\\text{Mass of salicylamide}=(1.06g/mL\times 3.65mL)=3.869g[/tex]
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] .....(1)
Given mass of salicylamide = 3.869 g
Molar mass of salicylamide = 137.14 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of salicylamide}=\frac{3.869g}{137.14g/mol}=0.0295mol[/tex]
The chemical equation for the conversion of salicylamide to iodo-salicylamide follows:
[tex]\text{salicylamide }+NaI+NaOCl+EtOH\rightarrow \text{iodo-salicylamide }[/tex]
By Stoichiometry of the reaction:
1 mole of salicylamide produces 1 mole of iodo-salicylamide
So, 0.0295 moles of salicylamide will produce = [tex]\frac{1}{1}\times 0.0295=0.0295moles[/tex] of iodo-salicylamide
Now, calculating the mass of iodo-salicylamide from equation 1, we get:
Molar mass of iodo-salicylamide = 263 g/mol
Moles of iodo-salicylamide = 0.0295 moles
Putting values in equation 1, we get:
[tex]0.0295mol=\frac{\text{Mass of iodo-salicylamide}}{263g/mol}\\\\\text{Mass of iodo-salicylamide}=(0.0295mol\times 263g/mol)=7.76g[/tex]
To calculate the percentage yield of iodo-salicylamide, we use the equation:
[tex]\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100[/tex]
Experimental yield of iodo-salicylamide = 5.33 g
Theoretical yield of iodo-salicylamide = 7.76 g
Putting values in above equation, we get:
[tex]\%\text{ yield of iodo-salicylamide}=\frac{5.33g}{7.76g}\times 100\\\\\% \text{yield of iodo-salicylamide}=68.68\%[/tex]
Hence, the percent yield of the reaction is 68.68%.
In this case, we can calculate the mass of the salicylamide and use it to calculate the theoretical yield. Then, we can calculate the actual yield and percent yield which is 57.38%
Explanation:To calculate the theoretical yield and percent yield of a reaction, we need to first determine the limiting reagent. From the given information, we know that 3.65 mL of salicylamide was reacted, which has a density of 1.09 g/mL. Therefore, the mass of salicylamide can be calculated as follows:
Mass = Volume x Density = 3.65 mL x 1.09 g/mL = 3.97 g
Next,
Moles of salicylamide used = mass / molar mass = 3.9825 g / 137.14 g/mol = 0.0291 mol
Moles of iodosalicylamide produced = Moles of salicylamide used = 0.0291 mol
Mass of iodosalicylamide produced = moles × molar mass = 0.0291 mol × 319.02 g/mol = 9.303 g
Therefore, the theoretical yield of iodosalicylamide is 9.303 g.
The percentage yield of the reaction can be calculated as follows:
= Actual yield / theoretical yield × 100
= (5.33 g / 9.303 g) × 100 = 57.38%
Therefore, the percentage yield of the reaction is 57.38%.
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Atmospheric pressure decreases as altitude increases. In other words, there is more air pushing down on you at sea level, and there is less air pressure pushing down on you when you are on a mountain.If hexane (C6H14), octane (C8H18), and octanol (C8H17OH) are heated evenly at different altitudes, rank them according to the order in which you would expect them to begin boiling.
Explanation:
Boiling point is the temperature at which vapor pressure of a liquid becomes equal to the atmospheric pressure.
So, more is the number of carbon atoms present in a compound that are linearly attached to each other more will be its boiling point. This is because then there are more intermolecular forces present in it and also it occupies more surface area.
Hence, in order to break these intermolecular forces more heat is required. As a result, boiling point of the compound increases.
Therefore, we can conclude that given compounds are ranked according to the increasing order in which you would expect them to begin boiling as follows.
Hexane at high altitude < Octane at high altitude < Octane at sea level < Octanol at sea level
A solution of sodiumhydroxide (NaOH) was standardized against potassium hydrogenphthalate (KHP). A known mass of KHP was titrated with
the NaOH solution until a light pink color appeared usingphenolpthalein indicator. Using the volume of NaOH requiredto neutralize KHP and the
number of moles of KHP titrated, the concentration of the NaOHsolution was calculated.
A vinegar (acetic acid) solution of unknown concentration wastitrated to the light pink endpoint with the standardized NaOHsolution. The
molarity and weight\volume % of the vinegar solution werecalculated.
A vitamin C (ascorbic acid) tablet was dissolved in approximately50 mL of distilled water and titrated with the standardized NaOHsolution. From
the results of this titration, the mg of ascorbic acid in thetablet was calculated.
Molecular formulas:
Potassium hydrogen phthalate: HKC8H4O4
Acetic acid: C2H4O2
Ascorbic acid: C6H8O6
Assume that all 3 acids are monoprotic acids.
Mass of KHP used forstandardization (g) 0.5591
Volume of NaOH required to neutralize KHP (mL) 13.39
Volume of vinegar sample titrated (mL) 5.00
Volume of NaOH required to neutralize vinegar in(mL) 8.38
Molecular weight of ascorbic acid (g/mol) 176.1271
Volume of NaOH required to neutralize ascorbic acid in Vitamin Ctablet (mL) 13.56
Calculate thefollowing
A. What is the Molecular Weight of KHP (HKC8H4O4) in g/mol?
B. How many moles of KHP were used in the standardization of theNaOH solution?
C. Calculate the concentration of NaOH solution in (mol/L).
D. Calculate the molarity of the vinegar solution (mol/L).
E. Calculate the weight/volume percentage of the vinegar solution(g/100 mL).
F. Calculate the amount of ascorbic acid in the Vitamin C tablet in(mg).
Answer:
See explanation below
Explanation:
In order to solve this, we'll do it by parts, as this exercise takes some time to solve it, however, the procedure it's pretty easy to understand.
A. Molecular weight of the KHP
To do this, we need the atomic weight of each element of the KHP. These are the following:
H = 1 g/mol; K = 39 g/mol; C = 12 g/mol; O = 16 g/mol
Now, let's calculate the molecular weight. Remember to multiply the number of atoms by the atomic weight:
MM KHP = (1*5) + (39) + (4*16) + (12*8) = 204 g/mol
B. moles of KHP used
In this part, we already have the molecular weight, so, we can calculate the moles with the expression:
n = m/MM (1)
The mass used of KHP is 0.5591 so the moles are:
n = 0.5591/204 = 2.74x10⁻³ moles
C. Concentration of NaOH
As the problem states, the KHP can be considered as a monoprotic acid, therefore, we can assume that the mole ratio between NaOH and KHP is 1:1 and we can use the following expression to calculate the concentration of the base:
MaVa = MbVb (2)
But moles:
n = M*V (3)
We have the moles of the KHP used, and the volume used to standarize the base, so we can solve for Molarity of the base:
Mb = na / Vb
Mb = 2.74x10⁻³ / 0.01339 = 0.2046 M
D. Molarity of vinegar solution
Using expression (2), we can calculate the vinegar solution, as we have the base volume used and volume of vinegar so:
MaVa = MbVb
Ma = MbVb/Va
Ma = 0.2046 * 8.38 / 5 = 0.3429 M
E. %W/V of vinegar
In this case, we use the following expression:
%W/V = mass solute / V solution * 100 (4)
The volume of solution would be the volume of the vinegar and volume of the base:
V solution = 8.38 + 5 = 13.38 mL
The mass of vinegar can be calculated, we have the concentration and volume, we can calculate the moles using expression (3):
n = 0.3429 * 0.005 = 1.71x10⁻³ moles
The mass of vinegar using the molecular weight of acetic acid (60 g/mol):
m = 1.71x10⁻³ * 60 = 0.1026 g
So the %:
%W/V = 0.1026/13.38 * 100 = 0.77%
F. mg of ascorbic acid
We do the same thing as in part C and then, the mass of ascorbic acid can be calculated with the molecular weight:
MaVa = MbVb = na
na = 0.2046 * 0.01356 = 2,77x10⁻³ moles
m = 2.77x10⁻³ * 176.1271 = 0.4878 g or simply 487.8 mg
A) The Molecular Weight of KHP is 204.23 g/mol. B). Moles of KHP were used in the standardization of the NaOH solution .C) The concentration of NaOH is 0.2045 mol/L. D). The vinegar solution's molarity is 0.3426 mol/L, and E).it has a weight/volume percentage of 2.06%, while F). the Vitamin C tablet contains 487 mg of ascorbic acid.
Let's go step by step to find each required value:
A. The Molecular Weight of KHP (HKC₈H₄O₄) in g/mol :
The molecular formula of KHP (Potassium hydrogen phthalate) is HKC₈H₄O₄. Thus:
K: 39.10 g/molH₅: 5 × 1.01 g/mol = 5.05 g/molC₈: 8 × 12.01 g/mol = 96.08 g/molO₄: 4 × 16.00 g/mol = 64.00 g/molAdding these values gives us the Molecular Weight of KHP: 204.23 g/mol.
B. Moles of KHP were used in the standardization of the NaOH solution :
Moles of KHP = Mass of KHP / Molecular Weight of KHP
= 0.5591 g / 204.23 g/mol
= 0.002737 moles
= 2.74x10⁻³ moles
C. The concentration of NaOH solution in (mol/L) :
Molarity (M) = Moles of Solute / Volume of Solution in L
Volume of NaOH in L = 13.39 mL × (1 L / 1000 mL) = 0.01339 L
Thus, Molarity of NaOH = 0.002737 moles / 0.01339 L
= 0.2045 mol/L
D. The molarity of the vinegar solution (mol/L) :
Firstly, we know the mole ratio between acetic acid (CH₃COOH) and NaOH is 1:1.
Moles of NaOH used for vinegar = Molarity of NaOH × Volume in L
= 0.2045 mol/L × 0.00838 L
= 0.001713 moles
Since it’s a 1:1 ratio, the moles of acetic acid (CH₃COOH) in the vinegar is 0.001713 moles
Molarity of vinegar = Moles of Acetic Acid / Volume of Vinegar Solution in L
Molarity of Vinegar = 0.001713 moles / 0.005 L
= 0.3426 mol/L
E. The weight/volume percentage of the vinegar solution (g/100 mL) :
Weight of Acetic Acid (CH₃COOH) in grams = Moles × Molecular Weight
= 0.001713 moles × 60.05 g/mol = 0.1029 g
Since the vinegar sample was 5.00 mL, weight/volume %
= (0.1029 g / 5.00 mL) × 100 = 2.06%
F) . The amount of ascorbic acid in the Vitamin C tablet in (mg) :
Moles of NaOH used = Molarity of NaOH × Volume in L
= 0.2045 mol/L × 0.01356 L = 0.002774 moles
Since mole ratio between ascorbic acid and NaOH is 1:1, moles of ascorbic acid = 0.002774 moles
Mass of ascorbic acid = Moles × Molecular Weight = 0.002774 moles × 176.1271 g/mol = 0.487 grams
Thus, mass in mg = 0.487 g × 1000 = 487 mg
At a particular temperature, Kp 0.25 for the reaction a. A ask containing only N2O4 at an initial pressure of 4.5 atm is allowed to reach equilibrium. Calculate the equilibrium partial pressures of the gases. b. A ask containing only NO2 at an initial pressure of 9.0 atm is allowed to reach equilibrium. Calculate the equilibrium partial pressures of the gases. c. From your answers to parts a and b,does it matter from which direction an equilibrium position is reached?
Answer:
a. pNO₂ = 1 atm pN₂O₄ = 4 atm
b. pNO₂ = 1 atm pN₂O₄ = 4 atm
c. It does not matter.
Explanation:
From the information given in this question we know the equilibrium involved is
N₂O₄ (g) ⇄ 2 NO₂ (g)
with Kp given by
Kp = p NO₂²/ p N₂O₄ = 0.25
We know that if we place 4.5 atm of N₂O₄ is placed in a flask, a quantity x is going to be consumed producing 2x atm of NO₂ and we can setup the following equation:
0.25 = p NO₂²/ p N₂O₄ = (2x)² / (4.5 - x)
0.25 x (4.5 - x) = 4x²
4x² + 0.25 x - 1.125 = 0
after solving this quadratic equation, we get two roots
x₁ = 0.5
x₂ = -0.56
the second root is physically impossible, and the partial pressures for x₁ = 0.5 will be
pNO₂ = 2 x 0.5 atm = 1.0 atm
pN₂O₄ = (4.5 - 0.5) atm = 4.0 atm
Similarly for part b, we get the equilibrium equation
0.25 = (9- 2x)² / x
0.25x = 81 - 36x + 4x²
the roots of this equation are:
x₁ = 5.0625
x₂ = 4
the first root is physically impossible since it will give us a negative partial pressure of N₂O₄ :
p N₂O₄ = 9 - 2(5.0625) = -1.13
the second root give us the following partial pressures:
p N₂O₄ = (9 - 2x4) atm = 1 atm
p NO₂ = 4 atm
The partial pressures are the same, it does not matter from which direction an equilibrium position is reached since what is essential is that the partial pressures of the gasses N₂O₄ and NO₂ obey the equilibrium equation.
Which of the following statements about photosynthesis is correct? (multiple answers may be correct) A: Carbon dioxide serves as final acceptor of high energy electrons provided by the light reactions B: Water serves only as an electron donor in oxygenic photosynthesis C: The oxygen released by oxygenic photosynthesis originates from water D: Hydrogen sulfide can also serve as electron donor in oxygenic photosynthesis E: in anoxygenic photosynthesis carbon dioxide does not serve as final electron acceptor.
Statements B, C, and E are correct about photosynthesis. Water serves as an electron donor in oxygenic photosynthesis and the oxygen released by oxygenic photosynthesis does indeed come from water. In anoxygenic photosynthesis, carbon dioxide is not the end electron acceptor.
Explanation:Among the listed statements about photosynthesis, B: Water serves only as an electron donor in oxygenic photosynthesis, and C: The oxygen released by oxygenic photosynthesis originates from water are correct. During photosynthesis, water is split, releasing electrons and protons, and providing the oxygen gas. In addition, statement E: in anoxygenic photosynthesis carbon dioxide does not serve as final electron acceptor is also correct. In anoxygenic photosynthesis, carried out by certain types of bacteria, something other than water provides the electrons, and carbon dioxide does not serve as the final electron acceptor.
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Statements B, C, and E are correct in regards to photosynthesis. In oxygenic photosynthesis, water acts as an electron donor, and oxygen is released as a byproduct, originating from water. In anoxygenic photosynthesis, carbon dioxide does not serve as the final electron acceptor.
Explanation:Based on the provided information, statements B, C, and E are correct. Let's explain why.
B: In oxygenic photosynthesis, water indeed serves as an electron donor. It helps in replacing the reaction center electron, and as a byproduct, oxygen is formed.
C: The oxygen released by oxygenic photosynthesis indeed originates from water. When water serves as an electron donor and is split, oxygen is released.
E: In anoxygenic photosynthesis, carbon dioxide does not serve as the final electron acceptor. Instead, other reduced molecules like hydrogen sulfide or thiosulfate may be used as the electron donor. Here, oxygen is not formed as a byproduct.
Statements A and D are incorrect. In photosynthesis, Carbon dioxide does not serve as the final acceptor of high energy electrons -- NADP+ does. Besides, Hydrogen sulfide can serve as an electron donor, but not in oxygenic photosynthesis.
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If the final pressure on the gas is 1.20 atm , calculate the entropy change for the process. Check lecture notes or textbook for the formula connecting the change of entropy and gas volume. Assume that neon behaves as an ideal gas in this experiment.
Answer: [tex]-2.34\frac{J}{K}[/tex]
Explanation:
In thermodynamics, entropy (symbolized as S) is a physical quantity for a thermodynamic system in equilibrium. It measures the number of micro states compatible with the macro state of equilibrium, it can also be said that it measures the degree of organization of the system, or that it is the reason for an increase in internal energy versus an increase in the temperature of the system.
If we assume we have 0.6 mol of an ideal gas at 350 K at an initial pressure of 0.75 atm, we calculate the entropy change as:
[tex]S=nRln\frac{P1}{P2}[/tex]
Where S is entropy, n is the number of moles, R is the gas constant R is 8.314 J / mol·K, P1 is the initial pressure and P2 is the final pressure. Then we substitute the values and solve for S.
[tex]S= (0.6 mol).(8.3145\frac{J}{mol.k})(ln\frac{0.75atm}{1.2atm})[/tex]
[tex]S= -2.34\frac{J}{K}[/tex]
The question is not complete and the complete question is ;
the pressure on 0.600 mol of an ideal gas at 350 K is increased isothermally from an initial pressure of 0.750 atm (b) If the final pressure on the gas is 1.20 atm, calculate the entropy change for the process.
Answer:
Entropy change = -2.34 J/k
Explanation:
In thermodynamics, the entropy of a system is expected to increase with increase in temperature, increase in volume, or increase in number of gas particles.
Now, the gas is expanded isothermally and so its temperature is constant. Thus, as pressure of an ideal gas increases, the number of microstates possible for a system decreases and this results in the decrease of reaction entropy and thus is negative.
Thus, ΔS = nRIn(P1/P2)
Now, from the question,
n = 0.06 moles
P1 = 0.75 atm and P1=1.2 atm
R is gas constant and is 8.3145 J/kg.mol
Thus, ΔS = 0.06 x 8.3145 x In(0.75/1.2) = -2.34 J/k
he rate constant for this zero‑order reaction is 0.0130 M ⋅ s − 1 at 300 ∘ C. A ⟶ products How long (in seconds) would it take for the concentration of A to decrease from 0.890 M to 0.280 M?
Answer:
188 s
Explanation:
We are told the reaction is second order respect to A so we know the expression for the rate law is
rate = - Δ[A]/Δt = k[A]²
where the symbol Δ stands for change, [A] is the concentration of A, and k is the rate constant.
The integrated rate law for this equation from calculus is
1 / [A]t = kt + 1/[A]₀
where [A]t is the concentration of A at time t, k is the rate constant, and [A]₀ is the initial concentration.
Since we have all the information required to solve this equation lets plug our values
1 / 0.280= 0.0130x t + 1 / 0.890
( 1 / 0.280 - 1 / 0.890)M⁻¹ = 0.0130 M⁻¹ ·s⁻¹t
t = 188 s
A buffer solution that is 0.100 M in both HCOOH and HCOOK has a pH = 3.75. A student says that if a very small amount of 0.100 M HCl is added to the buffer, the pH will decrease by a very small amount. Which of the following best supports the student's claim? (A) HCOO will accept a proton from HCl to produce more HCOOH and H2O(B) HCOOH will accept a proton from HCl to produce more HCOO and H2O. (C) HCOO wil donate a proton to HCl to produce more HCOOH and H2O (D) HCOOH will donate a proton to HCl to produce more HCOO and H2O.
Answer: Option (A) is the correct answer.
Explanation:
Chemical equation for the given reaction is as follows.
[tex]HCOO^{-}(aq) + H^{+}(aq) \rightarrow HCOOH(aq)[/tex]
And, the expression to calculate pH of this reaction is as follows.
pH = [tex]pk_{a} + log \frac{[HCOO^{-}]}{[HCOOH]}[/tex]
As the concentration of [tex]HCOO^{-}[/tex] is directly proportional to pH. Hence, when there occurs a decrease in the pH of the solution the [tex][HCOO^{-}][/tex] will also decrease.
Thus, we can conclude that the statement, HCOO will accept a proton from HCl to produce more HCOOH and [tex]H_{2}O[/tex], best supports the student's claim.
The correct option is (A) HCOO will accept a proton from HCl to produce more HCOOH and H.
To understand why option (A) best supports the student's claim, let's consider the buffer system and the effect of adding a small amount of HCl.
A buffer solution consists of a weak acid and its conjugate base, or a weak base and its conjugate acid. In this case, the buffer is composed of formic acid (HCOOH), a weak acid, and its conjugate base, the formate ion (HCOO), along with the potassium salt (HCOOK). The Henderson-Hasselbalch equation relates the pH of the buffer to the concentrations of the weak acid and its conjugate base:
[tex]\[ \text{pH} = \text{pK}_a + \log \left( \frac{[\text{HCOO}^-]}{[\text{HCOOH}]} \right) \][/tex]
Given that the pH of the buffer is 3.75 and the concentrations of HCOOH and HCOO are both 0.100 M, we can calculate the pKa of formic acid:
[tex]\[ 3.75 = \text{pK}_a + \log \left( \frac{0.100}{0.100} \right) \][/tex]
[tex]\[ 3.75 = \text{pK}_a + \log(1) \][/tex]
[tex]\[ 3.75 = \text{pK}_a \][/tex]
When a small amount of 0.100 M HCl is added to the buffer, the HCl (a strong acid) will dissociate completely into H and Cl ions. The H ions will then react with the formate ions (HCOO) in the buffer, as they are the base component of the buffer system:
[tex]\[ \text{HCOO}^- (aq) + \text{H}^+ (aq) \rightarrow \text{HCOOH} (aq) \[/tex]
This reaction will produce more HCOOH and consume some of the added H ions, thus minimizing the change in pH. The formic acid (HCOOH) will not accept a proton from HCl because it is already protonated; instead, it can only donate a proton, which is not favorable in this case since HCl is a stronger acid.
Option (B) is incorrect because HCOOH cannot accept a proton; it is the acid component of the buffer.
Option (C) is incorrect because HCOO does not donate a proton to HCl; rather, it accepts a proton from HCl.
Option (D) is incorrect because HCOOH does not donate a proton to HCl; HCOOH is a weaker acid than HCl, so it does not donate a proton to HCl's protons.
Therefore, the student's claim that the pH will decrease by a very small amount upon the addition of a small amount of HCl is supported by the fact that the formate ions (HCOO) will accept protons from HCl to produce more formic acid (HCOOH), thus resisting a large change in pH, which is the defining characteristic of a buffer solution.
Insert the IF statement in cell I9 to determine if the % Down is greater than or equal to 20% Down Pmt Rate. If true, the PMI is 0. If false, the PMI is calculated by multiplying the Amount Financed by the PMI Rate divided by the # of Pmts Per Year. The function should be =IF(E9>=$B$7,0,D9*$B$6/$B$5).
To address a conditional situation in Excel, you would use the IF function. In this case, the asked function is =IF(E9>=$B$7, 0, D9*$B$6/$B$5), wherein a condition is evaluated and if true, returns 0, if false, conducts a specified calculation.
Explanation:The question asked is about using the IF statement in Excel, which falls under the Computers and Technology topic. Excel's IF function is used to create conditional statements, where different calculations can be performed depending on whether a particular condition is met.
For the given question, you are asked to insert the IF function in cell I9. The condition to test is if the value in cell E9 is greater than or equal to the value in cell B7. If this condition is true, the function will return 0. If the condition is not met, the function will execute a calculation: it multiplies the values in cells D9 and B6, then divides the result by the value in cell B5.
Your final function should look like this: =IF(E9>=$B$7,0,D9*$B$6/$B$5).
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A 30.0-mL sample of an unknown strong base is neutralized after the addition of 12.0 mL of a 0.150 M HNO3 solution. If the unknown base concentration is 0.0300 M, give some possible identities for the unknown base.
The question is incomplete, here is the complete question:
A 30.0-mL sample of an unknown strong base is neutralized after the addition of 12.0 mL of a 0.150 M HNO₃ solution. If the unknown base concentration is 0.0300 M, give some possible identities for the unknown base. (Select all that apply)
A.) Ca(OH)₂
B.) LiOH
C.) Sr(OH)₂
D.) Al(OH)₃
E.) NaOH
F.) Ba(OH)₂
Answer: The unknown base could be [tex]Ca(OH)_2,Sr(OH)_2\text{ or }Ba(OH)_2[/tex]
Explanation:
To calculate the number of moles for given molarity of solution, we use the equation:
.......(1)
For nitric acid:Molarity of solution = 0.150 M
Volume of solution = 12.0 mL
Putting values in equation 1, we get:
[tex]0.150M=\frac{\text{Moles of nitric acid}\times 1000}{12.00}\\\\\text{Moles of nitric acid}=\frac{0.150\times 12.00}{1000}=1.8\times 10^{-3}moles[/tex]
For unknown base:Molarity of solution = 0.0300 M
Volume of solution = 30.0 mL
Putting values in equation 1, we get:
[tex]0.0300M=\frac{\text{Moles of unknown base}\times 1000}{30.00}\\\\\text{Moles of unknown base}=\frac{0.0300\times 30.00}{1000}=0.9\times 10^{-3}moles[/tex]
Mole ratio of acid and base is calculated as: [tex]\frac{\text{Moles of unknown base}}{\text{Moles of nitric acid}}=\frac{0.9\times 10^{-3}}{1.8\times 10^{-3}}=\frac{2}{1}[/tex]
Number of [tex]OH^-[/tex] = 2 × number of [tex]H^+[/tex] ions
So, the unknown base is diprotic in nature.
Hence, the unknown base could be [tex]Ca(OH)_2,Sr(OH)_2\text{ or }Ba(OH)_2[/tex]
The unknown base could be a strong base such as sodium hydroxide (NaOH), potassium hydroxide (KOH), barium hydroxide (Ba(OH)2), or calcium hydroxide (Ca(OH)2), as these compounds release two hydroxide ions per molecule.
Explanation:To find the possible identities of the unknown strong base, we first need to understand the neutralization process which involves the reaction of an acid and a base to produce water and salts.
The neutralization reaction is given by: HNO3 + BOH -> H2O + BNO3 where B is the cation from the unknown base. From the stoichiometry of the reaction, we can see that 1 mole of HNO3 reacts with 1 mole of the unknown base.
The number of moles of HNO3 = volume (in L) x molarity = 0.012 L x 0.150 mol/L = 0.0018 mol. So, the number of moles of the unknown base would also be 0.0018 mol.
The molarity of the unknown base = number of moles / volume (in L) = 0.0018 mol / 0.030 L = 0.060 M. But the problem states that the concentration of the unknown base is 0.030 M, which means for every molecule of base, there are two hydroxide ions.
Therefore, the unknown base could be a strong base such as sodium hydroxide (NaOH), potassium hydroxide (KOH), barium hydroxide (Ba(OH)2), or calcium hydroxide (Ca(OH)2), etc., which are all examples of sets of strong bases that release two hydroxide ions per molecule.
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Aqueous hydrochloric acid reacts with solid sodium hydroxide to produce aqueous sodium chloride and liquid water what is the terorectical yield of water formed from the reaction of 3.3 g of hydrocloric acid and 6.6g of sodium hydroxide?
Answer:
1.63 g of H₂O is the theoretical yield
Explanation:
We determine the reactants for the reaction:
HCl, NaOH
We determine the products for the reaction:
H₂O, NaCl
The equation for this neutralization reaction is:
HCl (aq) + NaOH(aq) → NaCl(aq) + H₂O(l)
We use both masses, from both reactants to determine the limiting.
First, we convert the mass to moles.
3.3 g . 1mol / 36.45 g = 0.090 moles of HCl
6.6 g . 1mol / 40 g = 0.165 moles of NaOH
Ratio is 1:1, so for 0.165 moles of hydroxide I need the same amount of acid. I have 0.090 HCl so the acid is the limiting reagent.
Let's work with stoichiometry. Ratio is 1:1, again.
1 mol of acid can produce 1 mol of water
Therefore, 0.090 moles of acid must produce 0.090 moles of H₂O
We convert the moles to mass, to define the theoretical yield
0.090 mol . 18g / 1 mol = 1.63 g
Answer:
The theoretical yield of H2O is 1.63 grams
Explanation:
Step 1: Data given
Mass of hydrochloric acid = 3.3 grams
Mass of sodium hydroxide = 6.6 grams
Molar mass hydrochloric acid (HCl) = 36.46 g/mol
Molar mass sodium hydroxide (NaOH) = 40.0 g/mol
Step 2: The balanced equation
HCl + NaOH → NaCl + H2O
Step 3: Calculate moles
Moles = mass / molar mass
Moles HCl = 3.3 grams / 36.46 g/mol
Moles HCl = 0.0905 moles
Moles NaOH = 6.6 grams / 40.0 g/mol
Moles NaOH = 0.165 moles
Step 4: Calculate the limiting reactant
HCl is the limiting reactant. There will react 0.0905 moles. NaOH is in excess. There will react 0.0905 moles moles. There will remain 0.165 - 0.0905 = 0.0745 moles
Step 5: Calculate moles H2O
For 1 mol HCl we need 1 mol NaOH to produce 1 mol NaCl and 1 mol H2O
For 0.0905 moles HCl we'll have 0.0905 moles H2O
Step 6: Calculate mass H2O
Mass H2O = moles * molar mass
Mass H2O = 0.0905 * 18.02 g/mol
Mass H2O = 1.63 grams
The theoretical yield of H2O is 1.63 grams
Iron‑59 is used to study iron metabolism in the spleen. Its half‑life is 44 days. How many days would it take a 28.0 g sample of iron‑59 to decay to 0.875 g?
The radioisotope will take 219 days to decay from 28 g to 0.875 g.
Explanation:
Any radioactive isotope is tend to decay with time. So the rate of decay of the radioactive isotopes is termed as disintegration constant. Since, the initial mass of the radioactive isotope is given along with the reducing mass. In order to determine the time required to reduce the mass of the radioisotope from 28 g to 0.875 g, first the disintegration constant is need to be determined. The disintegration constant can be obtained from half life time of the isotope. As half life time is the measure of time required to reduce half of the concentration of the isotope.
Half life time = 0.6932/disintegration constant
44 = 0.6932/λ
λ = 0.6932/44=0.0158
So, with this values of disintegration constant, initial mass and final mass, the time required to reduce from initial to final mass can be obtained using law of disintegration constant as follows.
N = Noe^(-λt)
[tex]t= -\frac{1}{disintegration constant}* ln(\frac{N}{N_{0} } )\\ \\t = -\frac{1}{0.0158}*ln(\frac{0.875}{28})\\ \\t = -\frac{1}{0.0158}*ln(0.03125)\\\\t = -63.29*(-3.466)\\\\t=219 days.[/tex]
Thus, the radioisotope will take 219 days to decay from 28 g to 0.875 g.
It would take 220 days for 28.0 g sample of iron‑59 to decay to 0.875 g
The half life of a substance is the amount of time it takes to decay to half of the initial value. It is given by:
[tex]N(t)=N_o(\frac{1}{2}) ^\frac{t}{t_\frac{1}{2} } \\\\N(t)=amount\ after\ t\ years, N_o=original\ value,t_\frac{1}{2} =half\ life\\\\Given\ that:\\\\N(t)=0.875g,N_o=28g,t_\frac{1}{2} =44\ days. hence:\\\\\\0.875=28(\frac{1}{2} )^\frac{t}{44} \\\\t=220\ days[/tex]
Hence it would take 220 days for 28.0 g sample of iron‑59 to decay to 0.875 g
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What is the name of the product of the reaction of 1-pentyne with one equivalent of Br2? (that means that there is one mole of Br2 for each mole of 1-pentyne).
Final answer:
The product of the reaction of 1-pentyne with one equivalent of Br2 is called 1,2-dibromopentene, resulting from a halogen addition reaction.
Explanation:
The reaction of 1-pentyne with one equivalent of Br2 leads to the addition of bromine across the triple bond. Given that there is only one mole of Br2 for each mole of 1-pentyne, the bromine will add to the first and second carbons of the 1-pentyne chain, resulting in a dibromoalkene. Therefore, the name of the product is 1,2-dibromopentene. This product is the result of a typical halogen addition reaction to an alkyne, where the more substituted carbon atom gets the first bromine atom due to the Markovnikov's rule; however, in this case the symmetry of the starting alkyne makes that irrelevant since both terminal carbons are equivalent.
In light of the nuclear model for the atom, which statement is true?
A) For a given element, the size of an isotope with more neutrons is larger than one with fewer neutrons.
B) For a given element, the size of an atom is the same for all of the element’s isotopes.
The true statement for nuclear model for the atom is B: For a given element, the size of an atom is the same for all of the element’s isotopes is
Explanation:
The isotopes are the atoms of an element that have different number of neutrons in their nuclei but same number of electrons.
The number of protons remains the same in isotopes.
the atomic mass of the isotope differ because the atomic mass is number of proton+ number of neutrons.
The atomic number remains the same since number of protons equals the number of protons.
The atomic radii does not change because the arrangement or number of electrons do not differ among the isotopes. Since there is no change in atomic radii the size remains same in isotopes of an element. Although the size of nucleus increases due to more protons.
The correct option is B). The true statement is For a given element, the size of an atom is the same for all of the element’s isotopes.
In the nuclear model of the atom, the size of an atom is primarily determined by the number of protons in the nucleus, which is the same for all isotopes of a given element. This is because the number of protons determines the atomic number, and thus the number of electrons in a neutral atom.
Isotopes of an element have the same number of protons but different numbers of neutrons. While the addition of neutrons does increase the mass of the atom, it does not significantly affect the size of the atom. The electron cloud is attracted to the positively charged protons in the nucleus, and since the number of protons remains constant for all isotopes of an element, the size of the electron cloud, and therefore the atomic radius, remains relatively constant.
The presence of additional neutrons can have a very slight effect on the atomic radius due to the increased mass of the nucleus, which might lead to a slightly stronger attraction between the nucleus and the electrons.
uppose a system consists of 50 mg of organic compound dissolved in 1.00 mL of water (solvent 1). Compare the effectiveness of one 1.5-mL extraction versus three 0.5-mL extractions with ether (solvent 2) where the distribution coefficient, K, is equal to 10. Which is more effective
Answer: the more effective is using three 0.5-mL extractions with ether
Explanation:
Using 1.5 ml of ether
Q = [Vaq/(K×Vorg +Vaq)]^n
Q= remaining fraction
Vaq= volume of aqueous phase
Vorg= volume of organic phase
K= distribution coefficient
Using 1.5 ml ether once
Vaq= 1ml, K= 10, n=1
Q = [Vaq/(K×Vorg +Vaq)]^n
Q= [1/10×1.5+1)]^1 = 0.0625
Using 0.5ml ether 3 times
Q = [1/(10×0.5 +1)]^3= 0.0046
Hence using 0.5ml of ether 3 times is more effective
Which of the following aqueous solutions are good buffer systems? . 0.29 M perchloric acid + 0.15 M potassium perchlorate 0.16 M potassium acetate + 0.26 M acetic acid 0.18 M hydrofluoric acid + 0.12 M sodium fluoride 0.31 M hypochlorous acid + 0.28 M potassium hypochlorite 0.35 M ammonium bromide + 0.32 M ammonia
Answer:
Good buffer systems are:
Option B) Potassium acetate (KCH3COO) + acetic acid (CH3COOH).
Option C: Hydrofluoric acid (HF) + sodium fluoride (NaF)
Option D: Hypochlorous acid (HClO) + potassium hypochlorite (KClO):
Option E: Ammonium bromide (NH4Br) + ammonia (NH3)
Explanation:
Buffers consist in a mixture of a weak acid with its salt or a weak alkaly with its salt. All buffer systems are conformed by:
1) Weak acid + salt formed with conjugated base of the acid
or
2) Weak alkaly + salt formed with conjugated acid of the alkaly
It is very important these salts come from the weak acid or weak alkaly. It means, the anion of the acid must be the anion in the salt which is going to be part of the buffer system. On the other hand, the cation of the weak alkaly must be the cation of the salt which is going to form the salt in the buffer system.
Then, when we evaluate all options in this exercise, answers are the following:
Option A) Perchloric acid (HClO4) + potassium perchlorate (KClO4).
It is not a buffer system because HClO4 is a strong acid. A buffer requires a weak acid or weak alkaly. KClO4 is a salt formed by the conjugated base of HClO4, but a buffer requires two condition: Weak acid or alkaly + its salt.
Option B) Potassium acetate (KCH3COO) + acetic acid (CH3COOH).
This mixture is a buffer because it is formed by a weak acid (acetic acid) and its salt (KCH3COO is a salt coming from weak acid ---CH3COOH---).
Buffer component reactions:
Reaction weak acid: CH3COOH + H2O <-----> H3O+ + CH3COO-
Reaction salt in water: KCH3COO ---> K+ + CH3COO-
CH3COO- is the anion of the weak acid so it must be part of the salt in the buffer system. Then KCH3COO is a salt from CH3COOH.
Option C: Hydrofluoric acid (HF) + sodium fluoride (NaF)
This mixture is a buffer because it is formed by a weak acid (Hydrofluoric acid) and its salt (NaF is a salt coming from weak acid ---HF---).
Buffer component reactions:
Reaction weak acid: HF + H2O <-----> H3O+ + F-
Reaction salt in water: NaF ---> Na+ + F-
F- is the anion of the weak acid so it must be part of the salt in the buffer system. Then NaF is a salt from HF.
Option D: Hypochlorous acid (HClO) + potassium hypochlorite (KClO):
It is a buffer because it is formed by a weak acid (hypochlorous acid) and its salt (KClO is a salt coming from weak acid ---HClO---).
Buffer component reactions:
Reaction weak acid: HClO + H2O <-----> H3O+ + ClO-
Reaction salt in water: KClO ---> K+ + ClO-
ClO- is the anion of the weak acid so it must be part of the salt in the buffer system. Then KClO is a salt from HClO.
Option E: Ammonium bromide (NH4Br) + ammonia (NH3)
The combination of this weak alkaly (NH3) and the salt (ammonium bromide, NH4Br) is a buffer becuase it is formed by a weak compound and its salt.
Buffer component reactions:
Reaction weak alkaly: NH3 + H2O <-----> NH4+ + OH-
Reaction salt in water: NH4Br ---> NH4+ + OH-
NH4+ is the cation of the weak alkaly so it must be part of the salt in the buffer system. Then NH4Br is a salt from NH3.
Remember a buffer is formed by the combination of two different chemical sustances: Weak acid or Weak alkaly plus its salt.
Final answer:
Good buffer systems consist of a weak acid and its conjugate base or a weak base and its conjugate acid, capable of resisting changes in pH when acids or bases are added. Examples include mixtures of acetic acid with potassium acetate, hydrofluoric acid with sodium fluoride, hypochlorous acid with potassium hypochlorite, and ammonium bromide with ammonia.
Explanation:
Good buffer systems are made of a combination of a weak acid and its conjugate base, or a weak base and its conjugate acid. From the given options, a buffer system can be represented as follows:
0.16 M potassium acetate + 0.26 M acetic acid
0.18 M hydrofluoric acid + 0.12 M sodium fluoride
0.31 M hypochlorous acid + 0.28 M potassium hypochlorite
0.35 M ammonium bromide + 0.32 M ammonia
Each of these systems includes a weak acid or base along with its salt, which is made up of the conjugate base or acid. This combination allows the buffer to resist changes in pH when small amounts of acids or bases are added. For example, when considering acetic acid and sodium acetate as components of the buffer, the addition of a strong acid like HCl will react mainly with the acetate ions rather than causing a large change in pH.
how many moles of solute are in 300 mL of 1.5 M CaCl2? How many grams fo CaCl2 is this?
Answer:
1. 0.45 mole
2. 49.95g
Explanation:
The following were obtained from the question:
Volume of solution = 300mL = 300/1000 = 0.3L
Molarity = 1.5 M
Mole of CaCl2 =?
1. We can obtain the mole of the solute as follow:
Molarity = mole of solute /Volume of solution
1.5 = mole of solute/0.3
Mole of solute = 1.5 x 0.3
Mole of solute = 0.45 mole
2. The grams in 0.45 mole of CaCl2 can be obtained as follow:
Molar Mass of CaCl2 = 40 + (35.5 x 2) = 40 + 71 = 111g/mol
Mole of CaCl2 = 0.45 mole
Mass of CaCl2 =?
Mass = number of mole x molar Mass
Mass of CaCl2 = 0.45 x 111
Mass of CaCl2 = 49.95g
Answer:
We have 0.45 moles CaCl2 in this 1.5 M solution
This 49.9 grams of CaCl2
Explanation:
Step 1: data given
Volume of the CaCl2 solution = 300 mL = 0.300 L
Molarity of the CaCl2 solution = 1.5 M
Molar mass CaCl2 = 110.98 g/mol
Step 2: Calculate number of moles in the solution
Moles CaCl2 = molarity solution * volume of solution
Moles CaCl2 = 1.5 M * 0.300 L
Moles CaCl2 = 0.45 moles
Step 3: Calculate mass CaCl2
Mass CaCl2 = moles CaCl2 * molar mass CaCl2
Mass CaCl2 = 0.45 moles * 110.98 g/mol
Mass CaCl2 = 49.9 grams CaCl2
We have 0.45 moles CaCl2 in this 1.5 M solution
This 49.9 grams of CaCl2
On a balance, you have beakers of AgNO3AgNO3 solution and NaClNaCl solution. When mixed, they will form AgCl(s)AgCl(s). What will happen to the mass of the new mixture?
Explanation:
According to the law of conservation of mass, mass can neither be created nor it can be destroyed. But it can be simply transformed from one form to another.
Therefore, when [tex]AgNO_{3}[/tex] is added to NaCl then the compound formed will have same mass as that of reactants.
[tex]AgNO_{3} + NaCl \rightarrow AgCl + NaNO_{3}[/tex]
Total mass of reactants is (169.87 + 58.44) g/mol = 228.31 g/mol
Total mass of products is (143.32 + 84.99) g/mol = 228.31 g/mol
Thus, we can conclude that mass of the new mixture will stay the same.
A mixture of hydrochloric and sulfuric acids is prepared so that it contains 0.315 M HCl and 0.125 M H2SO4. What volume of 0.55 M NaOH would be required to completely neutralize all of the acid in 503.4 mL of this solution?
hints
involves a solution that has 2 different acids in it. One way to do this is to imagine that you are neutralizing 2 solutions, one of each acid, and then just add the amounts of base needed. Another way is to think about how many moles of H3O+ are present in the mixed acids, and then figure out how much of the basic solution is needed to react with that amount of H3O+.
Answer: The volume of NaOH required is 402.9 mL
Explanation:
To calculate the number of moles for given molarity, we use the equation:
[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}[/tex] .....(1)
For HCl:Molarity of HCl solution = 0.315 M
Volume of solution = 503.4 mL = 0.5034 L (Conversion factor: 1 L = 1000 mL)
Putting values in equation 1, we get:
[tex]0.315M=\frac{\text{Moles of HCl}}{0.5034L}\\\\\text{Moles of HCl}=(0.315mol/L\times 0.5034L)=0.1586mol[/tex]
For sulfuric acid:Molarity of sulfuric acid solution = 0.125 M
Volume of solution = 503.4 mL = 0.5034 L
Putting values in equation 1, we get:
[tex]0.125M=\frac{\text{Moles of }H_2SO_4}{0.5034L}\\\\\text{Moles of }H_2SO_4=(0.125mol/L\times 0.5034L)=0.0630mol[/tex]
As, all of the acid is neutralized, so moles of NaOH = [0.1586 + 0.0630] moles = 0.2216 moles
Molarity of NaOH solution = 0.55 M
Moles of NaOH = 0.2216 moles
Putting values in equation 1, we get:
[tex]0.55M=\frac{0.2216}{\text{Volume of solution}}\\\\\text{Volume of solution}=\frac{0.2216}{0.55}=0.4029L=402.9mL[/tex]
Hence, the volume of NaOH required is 402.9 mL
Acetic acid, ethanol, acetaldehyde and ethane form a series of 2-carbon molecules which differ in their extent of oxidation. Convert ethanol to the next more reduced form in that ordered series. HelpMarvin JS
Explanation:
Ethanol can be oxidized to ethanal or acetaldehyde which is further oxidized to acid that is acetic acid.
[tex]CH_3CH_2OH[/tex]→ [tex]CH_3CHO[/tex] [oxidation by loss of hydrogen]
An oxidizing agent potassium dichromate(VI) solution is used to remove the hydrogen from the ethanol. An oxidizing agent used along with dilute sulphuric acid for acidification.Acetaldehyde can also be reduced back to ethanol again by adding hydrogen to it by using a reducing agent that is sodium tetrahydro borate, NaBH4.
The oxidation of aldehydes to carboxylic acids can be done by the two-step process. In the first step, one molecule of water is added in the presence of a catalyst that is acidic. There is a generation of a hydrate. (geminal 1,1-diol).[tex]CH_3CHO[/tex] → [tex]CH_3CH_2COOH[/tex] [reduction by the gain of electrons]
Here, the oxidizing agent used is[tex]Cr_3O[/tex] in the presence of acetone.
To convert ethanol to the next more reduced form in the series, it will form an aldehyde called acetaldehyde.
Explanation:To convert ethanol to the next more reduced form in the series, we need to consider the oxidation level of the molecules. Ethanol is an alcohol with the -OH group bonded to a carbon atom attached to two other carbon atoms, which means it will form an aldehyde upon oxidation. Acetaldehyde is the next more reduced form in the series. Acetaldehyde has a carbonyl group (C=O) instead of an -OH group.
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A 0.10 M imidazole solution has a pH of 6.6. To the nearest hundredth of a unit, what fraction of the molecules are in the neutral (imidazole) form? (The pKa of the imidazolium ion is 6.0.)
Answer : The fraction of the molecules in the neutral (imidazole) form are, 0.799
Explanation : Given,
pH = 6.6
[tex]p_{K_a}=6.0[/tex]
Using Henderson Hesselbach equation :
[tex]pH=pK_a+\log \frac{[Salt]}{[Acid]}[/tex]
[tex]pH=pK_a+\log \frac{[\text{Imidazole}]}{[\text{Imidazolium ion}]}[/tex]
Now put all the given values in this expression, we get:
[tex]6.6=6.0+\log \frac{[\text{Imidazole}]}{[\text{Imidazolium ion}]}[/tex]
[tex]\frac{[\text{Imidazole}]}{[\text{Imidazolium ion}]}=10^{6.6-6.0}[/tex]
[tex]\frac{[\text{Imidazole}]}{[\text{Imidazolium ion}]}=10^{0.6}[/tex]
[tex]\frac{[\text{Imidazole}]}{[\text{Imidazolium ion}]}=3.98[/tex]
[tex][\text{Imidazole}]=3.98[\text{Imidazolium ion}][/tex] ...........(1)
Now we have to determine the fraction of the molecules are in the neutral (imidazole) form.
Fraction of neutral imidazole = [tex]\frac{[\text{Imidazole}]}{[\text{Imidazole}]+[\text{Imidazolium ion}]}[/tex]
Now put the expression 1 in this expression, we get:
Fraction of neutral imidazole = [tex]\frac{3.98[\text{Imidazolium ion}]}{3.98[\text{Imidazolium ion}]+[\text{Imidazolium ion}]}[/tex]
Fraction of neutral imidazole = [tex]\frac{3.98[\text{Imidazolium ion}]}{4.98[\text{Imidazolium ion}]}[/tex]
Fraction of neutral imidazole = [tex]\frac{3.98}{4.98}[/tex]
Fraction of neutral imidazole = 0.799
Thus, the fraction of the molecules in the neutral (imidazole) form are, 0.799
Final answer:
To find the fraction of imidazole molecules in their neutral form in a 0.10 M solution at pH 6.6, given a pKa of 6.0, we use the Henderson-Hasselbalch equation. The calculation shows that for every 4 molecules of neutral imidazole, there's about 1 deprotonated molecule, demonstrating a significant proportion of neutral molecules in the solution.
Explanation:
The question asks for the fraction of imidazole molecules in the neutral form when a 0.10 M solution of imidazole has a pH of 6.6, given that the pKa of the imidazolium ion is 6.0. This involves understanding the dissociation of acids in solution and applying the Henderson-Hasselbalch equation. The equation is: pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the deprotonated form and [HA] is the concentration of the protonated (neutral) form. Solving for the ratio [HA]/[A-] gives us the fraction of molecules in the neutral form.
In this scenario, rearranging the Henderson-Hasselbalch equation and substituting the given values (pH = 6.6 and pKa = 6.0) allows us to solve for the fraction of neutral imidazole molecules: 6.6 = 6.0 + log([HA]/[A-]). This results in a log([HA]/[A-]) of 0.6, which corresponds to a ratio of [HA]/[A-] equal to about 4. Thus, for every 4 molecules of neutral imidazole, there's approximately 1 deprotonated molecule, indicating a large fraction of the molecules remain in the neutral form at pH 6.6.
Which pair of elements do you expect to be most similar in their chemical properties? a. AgAg and KrKr b. OO and SS c. PbPb and OO d. AlAl and CaCa
Answer: Option (b) is the correct answer.
Explanation:
Chemical properties are defined as the properties which tend to chemical composition of a substance. Neutral elements with similar number of valence electrons tend to show similar chemical properties as these have same reactivity which actually affects their chemical properties.
This means that elements of the same group tend to show similar chemical properties.
For example, oxygen and sulfur atom are both group 16 elements and they have 6 valence electrons. Therefore, they show similar chemical properties.
Thus, we can conclude that a pair of O and S elements is expected to be most similar in their chemical properties.
A chemist adds 55.0mL of a ×1.710−5/mmolL mercury(II) iodide solution to a reaction flask. Calculate the micromoles of mercury(II) iodide the chemist has added to the flask. Be sure your answer has the correct number of significant digits.
Answer:
The answer is 0.017 μmol of mercury iodide
Explanation:
To know the micromoles we must use the following conversion, 1 mmol = 1000μmol. we use a rule of three for the calculation of micromoles:
1mmol------------------1000μmol
1.7x10^-5mmol------- Xμmol
Clearing the X, we have:
X μmol = (1.7x10^-5x1000)/1 = 0.017μmol
what is the job of a scientist?
A) To ignore facts that do not support his or her theory.
B) To answer ethical questions.
C) To ask and answer scientific questions.
D) To write laws based on his or knowlege.
Answer:
c i believe, not sure
Explanation:
While mercury is very useful in barometers, mercury vapor is toxic. Given that mercury has a ΔHvap of 59.11 kJ/mol and its normal boiling point is 356.7°C, calculate the vapor pressure in mm Hg at room temperature, 25°C. Group of answer choices 2.99 mm Hg 753 mm Hg 2.68 × 10-3 mm Hg 372 mm Hg
2.38×10^-3
Explanation:
from the question,the we calculate the latent heat of vaporization with the difference in temperature being put into consideration
Select the statements that are correct with respect to waste disposal in the Electrochemical Cells Experiment. (Select all that apply.)
a. Dilute copper and ascorbic acid solutions should be disposed of in the waste container in the hood.
b. Rinsings from the half-cell module can be flushed down the sink.
c. Metal and graphite electrodes should be rinsed with water, dried, and returned to their positions on the lab bench.
d. The contents of the half-cell module should be disposed of in the waste container in the hood.
e. No waste will be generated during this experiment.
f. The electrodes should be discarded in the proper jar.
Answer:A. Dilute copper and ascorbic acid solutions should be disposed of in the waste container in the hood.
C. Metal and graphite electrodes should be rinsed with water, dried, and returned to their positions on the lab bench.
D. The contents of the half-cell module should be disposed of in the waste container in the hood.
Explanation: An electrochemical cell is a cell that has the capability of producing Electric energy from chemical reaction (voltaic cells) or using Electric energy to make chemical reactions to take place(electrolytic cell). For a proper or effective waste disposal in an electrochemical cell the following options are correct.
Dilute copper and ascorbic acid solutions should be disposed of in the waste container in the hood.
Metal and graphite electrodes should be rinsed with water, dried, and returned to their positions on the lab bench.
The contents of the half-cell module should be disposed of in the waste container in the hood.
In the Electrochemical Cells Experiment, the correct statements regarding waste disposal include disposing copper and ascorbic acid solutions in the waste container, flushing rinsings from the half-cell module down the sink, and rinsing and drying the electrodes.
Explanation:The correct statements with respect to waste disposal in the Electrochemical Cells Experiment are:
Dilute copper and ascorbic acid solutions should be disposed of in the waste container in the hood.Rinsings from the half-cell module can be flushed down the sink.Metal and graphite electrodes should be rinsed with water, dried, and returned to their positions on the lab bench.The contents of the half-cell module should be disposed of in the waste container in the hood.No waste will be generated during this experiment.The electrodes should be discarded in the proper jar.The chemical formula for beryllium sulfide is BeS. A chemist measured the amount of beryllium sulfide produced during an experiment. She finds that 8.31 g of beryllium sulfide is produced. Calculate the number of moles of beryllium sulfide produced. Be sure your answer has the correct number of significant digits
Answer:
The answer is 0.20231 mol BeS
Explanation:
we look for the molecular weight of beryllium and sulfur in the periodic table:
molecular weight of Be = 9.01 g/mol
molecular weight of S = 32.065 g/mol
therefore, the molecular weight of beryllium sulfide is equal to:
molecular weight of BeS = 9.01 + 32.065 = 41.075 g/mol
The number of moles will be equal to:
[tex]n BeS = 8.31 g BeS x\frac{1 mol BeS}{41.075 g BeS}=0.20231 mol BeS[/tex]
Final answer:
To find the number of moles of BeS produced in the experiment, we calculate the molar mass of BeS (41.077 g/mol) and use the formula mass divided by molar mass. The result is 0.202 moles of beryllium sulfide from 8.31 g.
Explanation:
The question asks us to calculate the number of moles of beryllium sulfide (BeS) produced when a chemist measures 8.31 g of it. First, we need to calculate the molar mass of beryllium sulfide. Beryllium (Be) has an atomic mass of 9.012 g/mol, and sulfur (S) has an atomic mass of 32.065 g/mol. Therefore, the molar mass of beryllium sulfide is 9.012 g/mol + 32.065 g/mol = 41.077 g/mol.
To find the number of moles of BeS, we use the formula:
molar mass = mass / number of moles. Rearranging this formula to solve for the number of moles gives number of moles = mass / molar mass. Substituting the given values, we get number of moles = 8.31 g / 41.077 g/mol = 0.202 moles. Therefore, 8.31 g of beryllium sulfide is equivalent to approximately 0.202 moles, with the answer rounded to three significant digits as per the given mass.
Determine if each of the statements is True or False regarding the First Law of Thermodynamics.
1. If the system loses energy to the surroundings, the surroundings could also lose energy to the system.
2. If the system gains thermal energy from the surroundings, the temperature of the surroundings decreases.
3 If the system gains 25 kJ of energy from the surroundings without doing any work on the surroundings, the surroundings could lose 20 kJ of energy.
Answer:
1. False, 2. True, 3. False.
Explanation:
1. False, if the system loses energy to the surroundings, the surroundings receive such energy.
[tex]\Delta U_{sys}<0[/tex]
[tex]\Delta U_{sys} + \Delta U_{surr} = 0[/tex]
[tex]\Delta U_{sys} = -\Delta U_{surr}[/tex]
[tex]\Delta U_{surr}>0[/tex]
2. True, if the system gains more thermal energy, the temperature of the surroundings decreases.
[tex]Q_{sys} = \Delta U_{sys}, Q_{sys}>0\\Q_{surr} =\Delta U_{surr}\\\Delta U_{sys} = -\Delta U_{surr}\\Q_{sys} =-Q_{surr}\\C_{sys} \cdot \Delta T_{sys} = - C_{surr} \cdot \Delta T_{surr}\\\Delta T_{sys}>0,\Delta T_{surr}<0[/tex]
3. False. The surroundings could lose 25 kJ of energy.
1. When the system loses energy, the surrounding should receive the energy. So, it is false.
2. When the system gains thermal energy so the temperature should increase. So, it is true.
3. The surrounding should lose 25 kJ of energy. So, it is false.
First Law of Thermodynamics:a. When the system loses energy, the surrounding should receive the energy. So, it is false.
Like
[tex]\Delta U_{sys} <0\\\\\Delta U_{sys} + \Delta _{surr} = 0\\\\\Delta U_{sys} = -DeltaU_{surr}\\\\DeltaU_{surr} >0[/tex]
b. When the system gains thermal energy so the temperature should increase. So, it is true.
[tex]Q_{sys} = \Delta U_{sys}, Q_{sys}>0\\\\Q_{sys} = \Delta U_{surr}\\\\\Delta U_{sys} = - \Delta U_{surr}\\\\Q_{sys} = -Q{surr}\\\\C_{sys}.\Delta T_{sys} = -C_{surr}.\Delta T_{surr}\\\\\Delta T_{sys}>0,\Delta T_{surr}<0[/tex]
3. The surrounding should lose 25 kJ of energy. So, it is false.
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A solution contains 35 g of NaCl per 100 g of water at 25 ∘C. Is the solution unsaturated, saturated, or supersaturated?
The solution described is saturated as it contains NaCl at a concentration equal to its solubility at 25°C, meaning water has dissolved the maximal amount of NaCl it can at that temperature.
Explanation:The solution you've described is a saturated solution, as it contains NaCl at a concentration equal to its solubility at a given temperature, in this case 25°C. This means that the water has dissolved as much sodium chloride as it can at this temperature, and any additional NaCl would not dissolve.
A supersaturated solution, on the other hand, is a solution that contains more solute than is possible under stable equilibrium conditions. This state is achieved by adding excess solute, or by evaporation of the solvent. A supersaturated solution is unstable, and will return to its saturation point upon disturbance, causing the excess solute to precipitate out.
Lastly, an unsaturated solution contains less solute than the maximum amount that can be dissolved in the solvent at a given temperature. In this state, more solute can be added and dissolved.
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The solution containing 35 g of NaCl per 100 g of water at 25 °C is unsaturated.
To determine the saturation status of the solution, we need to compare the actual amount of solute (NaCl) dissolved in the solvent (water) with the maximum amount that can be dissolved at a given temperature, which is known as the solubility of the solute in the solvent.
The solubility of NaCl in water at 25 °C is approximately 36 g per 100 g of water. Since the given solution has 35 g of NaCl per 100 g of water, this is less than the solubility limit. Therefore, the solution can still dissolve more NaCl and is considered unsaturated.
If the solution had exactly 36 g of NaCl per 100 g of water, it would be saturated, meaning it has reached its maximum capacity to dissolve NaCl at that temperature. If it had more than 36 g of NaCl per 100 g of water, it would be supersaturated, which is a state where the solution contains more solute than would normally be possible at equilibrium.
The compound responsible for the characteristic smell of garlic is allicin, C 6H 10OS 2. The mass of 1.00 mol of allicin, rounded to the nearest integer, is ________ g. 34 162 86 61 19
Answer: The answer is 162g.
Explanation: To calculate the mass of a molecule, you have to find the molar mass of each element of the molecule.
Molar mass of C = 12g/mol
Molar mass of H = 1g/mol
Molar mass of O = 16g/mol
Molar mass of S = 32g/mol
From the allicin's formula, there are:
6 C = 6.12 = 72
10 H = 10.1 = 10
1 O = 1.16 = 16
2 S = 2.32 = 64
Adding them up:
C6H10OS2 = 72+10+16+64 = 162g/mol.
As it is requested 1 mol of allicin, it has 162g.
Answer:
162 g/mol
Explanation:
This problem requires us to calculate the molar mass of allicin, grs/mol. So with the atomic weights of the atoms in this compound, the molar mass will be the sum of the atomic weight multiplied by the number of atoms in the formula.
atomic weights ( g/mol )
C : 12.01 g/mol
H : 1.00 g/mol
O: 16.00 g/mol
S : 32.06 g/mol
Molar mass C₆H₁₀Os₂ (g/mol ) = 6 x 12.01 + 10 x 1.00 + 1 x 16 +2 x 32.06
= 162 g/mol (rounded to the nearest integer)