Answer:
0.0016 mol/(L.s)
Explanation:
The rate of a reaction (r) can be calculated by the initial concentration of the reagent, by the expression:
-r = k*[reagent]ⁿ
Where the minus sign represents that the reagent is disappearing, k is the rate constant, which depends on the temperature, and n is the order of the reaction. For the reaction with more than 1 reagent, each reagent will have its order, which is determined by experiments. So, for n = 0:
-r = 0.0016*(1.50)⁰
-r = 0.0016 mol/(L.s)
Final answer:
The rate of a zero-order reaction is equal to the rate constant, which in the case of the hydrogenation of ethylene using a nickel catalyst is 0.0016 mol L.
Explanation:
To determine the rate of reaction for a zero-order reaction, we use the rate law which states that the rate is independent of the concentration of the reactants. Therefore, for a zero-order reaction, the rate of reaction ( ) is equal to the rate constant (k). Given that the rate constant k is 0.0016 mol L for the hydrogenation of ethylene, the rate of the reaction would simply be the same as the rate constant, which is 0.0016 mol L
A student synthesized a nickel (II) ammonia complex with a molecular formula of [Ni(NH3)x(H2O)y]Clz. The amount of ammonia in the complex was analyzed using 0.2005M HCl. The student determined that the reaction required 20.02mL of HCl to react with 0.1550g of the nickel(II) ammonia complex. Answer the following questions.Atomic masses: Ni = 58.69g/mol; H= 1.00g/mol; O= 16.00g/mol; Cl = 35.45g/mol; N= 14.00g/mol(a) Determine the value for "z" in the compound. Briefly explain your reasoning. Hint: the complex salt must be electrically neutral (i.e. NO NET CHARGE)(b) Calculate the EXPERIMENTAL EQUIVALENT WEIGTH for the nickel(II) ammonia complex (i.e. grams of complex per mole of ammonia).(c) Based on the results from (a) and (b), propose a molecular formula for the neutral nickel(II) ammonia coordination complex. Show all your work. Hint: x+y≤6. Try different combinations of "x" and "y" to see which combination best matches the calculated experimental equivalent weight.
Answer:
Answers explained below
Explanation:
(a)Given,
Molecular formula of the complex = [Ni(NH3)x(H2O)y]Clz
(i) Ni is in +2 oxidation state in the complex.
(ii) NH3 and H2O are the neutral ligands but Cl is the negatively charged ligand.
(iii) complex is neutral
So, to make the nickel complex in +2 oxidation with neutral charge, we requires 2 Cl-.
Hence, form the above statements, we can say that here in the complex
z=2
(b) Molarity of HCl = 0.2005M
Volume of HCl used = 20.02mL = 20.02*10-3 L
Weight of the nickel(II) ammonia complex = 0.1550g
Reaction of HCl with Ammonia,
HCl (aq) + NH3 (aq) -> NH4Cl (aq)
HCl reacts with ammonia in 1:1 ratio to form ammonium salt (NH4Cl). That means 1 mol of HCl reacts with 1 mol of NH3.
So, we have to find number of moles of HCl used.
No. of moles of HCl used = Molarity of HCl * Volume of HCl used (L)
= 0.2005M * 20.02*10-3 L = 4.014*10-3 moles
Hence no. of moles of ammonia in the complex = No. of moles of HCl used = 4.014*10-3 mol
So, Experimental Equivalent Weight = Weight of the nickel(II) ammonia complex/ No. of moles of NH3
= 0.1550g / 4.014*10-3 mol
= 38.615 g/mol
Hence, Experimental Equivalent Weight = 38.615 g/mol
(c) Given,
x+y=< 6
Molar mass of [Ni(NH3)x(H2O)y]Clz = 58.69 + x(14.00+3*1) + y(16+2*1)+z(35.45)
= (58.69 + 17x + 18y + 35.45z) g/mol
Case1 x=6, y=0 and z=2
Molar mass of [Ni(NH3)6(H2O)0]Cl2 = (58.69 + 17*6 + 18*0 + 35.45*2) g/mol
= 58.69+102+70.90 = 231.59 g/mol
Experimental Equivalent Weight = 233.59/6 = 38.598 g/mol
So, This experimental equivalent weight is equal to the calculated experimental equivalent weight.
Hence the molecular formula of the complex is [Ni(NH3)6]Cl2 where x=6, y=0 and z=2.
Note: You can try other combination but in every case you will find lower or higher calculated experimental equivalent weight.
The natural abundance of 13C is 1.1%. What are the relative peak heights of the M+ and M+1 peaks in the mass spectrum of decane? How do you know?
a. 100:11
b. 89:11
c. 100:1.1
d. 1:1.1
Answer:
a. 100:11
Explanation:
M+1 peak is observed due to the presence of an isotope of an atom in a molecule. Decane has the molecular formula C₁₀H₂₂, so the probability of having 13C atom in this molecule increases ten times. This gives the ratio between M+ and M+1 peak 100:11.
It should be noted that the decane molecule also contains hydrogen atoms whose isotope deuterium (2H) can also be present in the molecule and give M+1 peak. But its relative abundance to protium (1H) is low i.e., 0.015, so its effect can be neglected.
A simple formula for the estimation of the relative peak height of M+1 in a molecule that contains C, H, N, O, F, Si, P, and S is:
[tex][M+1] = (number of C X 1.1) + (number of H X 0.015) + (number of N X 0.37) + (number of O X 0.04) + (number of S X 0.8) + (number of Si X 5.1)[/tex]
PS: remove the element from the formula which is not present in the molecule
An electric range burner weighing 683.0 grams is turned off after reaching a temperature of 477.6°C, and is allowed to cool down to 23.2°C.
Calculate the specific heat of the burner if all the heat evolved from the burner is used to heat 552.0 grams of water from 23.2°C to 80.3°C.
Answer:
0.102 cal/g.°C
Explanation:
According to the law of conservation of energy, the sum of the heat released by the electric burner (Qb) and the heat absorbed by the water (Qw) is zero.
Qb + Qw = 0
Qb = -Qw
Both heats can be calculated using the following expression.
Q = c × m × ΔT
where,
c: specific heat
m: mass
ΔT: change in the temperature
Then,
Qb = -Qw
cb × mb × ΔTb = - cw × mw × ΔTw
cb = - cw × mw × ΔTw / mb × ΔTb
cb = - (1 cal/g.°C) × 552.0 g × (80.3°C - 23.2°C) / 683.0 g × (23.2°C - 477.6°C)
cb = 0.102 cal/g.°C
If you were to use Lewis theory to predict the formula for the compound between rubidium and fluorine, it would most likely be:
A. Rb2F
B. RbF
C. RbF2
D. Rb3F
Answer: The formula of the compound formed between rubidium and fluorine is RbF
Explanation:
Ionic bond is defined as the bond which is formed by complete transfer of electrons from one atom to another atom.
The atom which looses the electron is known as electropositive atom and the atom which gains the electron is known as electronegative atom. This bond is usually formed between a metal and a non-metal.
Rubidium is the 37th element of the periodic table having electronic configuration of [tex]1s^22s^22p^63s^23p^64s^23d^{10}4p^65s^1[/tex]
This will loose 1 electron to form [tex]Rb^+[/tex] ion
Fluoride is the 9th element of the periodic table having electronic configuration of [tex]1s^22s^22p^5[/tex]
This will gain 1 electron to form [tex]F^-[/tex] ion
To form [tex]RbF[/tex] compound, 1 rubidium ion is needed to neutralize the charge on fluoride ion
The formation of the given compounds is shown in the image below.
Arrange the following aqueous solutions in terms of freezing point depression with the least depression first: 0.45m CaCl2, 0.45m glucose or 0.45m NaCl? Then determine the freezing point depression for each. For water, Kf=1.86 C/m
Explanation:
Relation between [tex]k_{f}[/tex], molality and temperature is as follows.
T = [tex]K_{f} \times m \times i[/tex]
It is also known as depression between freezing point where, i is the Van't Hoff factor.
Let us assume that there is 100% dissociation. Hence, the value of i for these given species will be as follows.
i for [tex]CaCl_{2}[/tex] = 3
i for glucose = 1
i for NaCl = 2
Depression in freezing point will have a negative sign. Therefore, d
depression in freezing point for the given species is as follows.
[tex]T_{CaCl_{2}} = -1.86 \times 0.45 \times 3[/tex]
= [tex]-2.511^{o}C[/tex]
[tex]T_{glucose} = 1.86 \times 0.45 \times 1[/tex]
= [tex]-0.837^{o}C[/tex]
[tex]T_{NaCl} = -1.86 \times 0.45 \times 2[/tex]
= [tex]-1.674^{o}C[/tex]
Therefore, we can conclude that given species are arranged according to their freezing point depression with the least depression first as follows.
Glucose < NaCl < [tex]CaCl_{2}[/tex]
In the previous question, you calculated the amount of CO2 that was required to heat the air in your room. Which of the following are true statements?
Explanation:
In the previous question, you calculated the amount of CO2 that was required to heat the air in your room. Which of the following are true statements?
You didn't complete the above question, please complete the question and reupload, thanks for your anticipated cooperation.
Aqueous solutions of sodium hydroxide and magnesium chloride are mixed, resulting in the precipitate formation of magnesium hydroxide with aqueous sodium chloride as the other product. Write the balance chemical equation for this reaction
Answer: [tex]2NaOH(aq)+MgCl_2(aq)\rightarrow NaCl(aq)+Mg(OH)_2(s)[/tex]
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
[tex]2NaOH(aq)+MgCl_2(aq)\rightarrow NaCl(aq)+Mg(OH)_2(s)[/tex]
What is the minimum % relative error for a 0.5M NaOH solution?
Assume the absolute error is +/- 0.1.
Answer: 20%
Explanation:
Relative error = Absolute error/actual value
= 0.1/0.5
= 0.2
Hence,
Minimum % Relative error = 0.2 ×100%
= 20%
Answer:20%
Explanation:
Let us take some important definitions of some terms in the question.
What is an ABSOLUTE ERROR?.
Absolute error is the difference between the expected value and the value you got from an experimental calculations or the approximations made. It can be represented mathematically in the equation (1) below;
Absolute error= expected value - Approximated/measured value. ---------------------------------------------------------------------(1).
What is A RELATIVE ERROR?.
A relative error is the the ratio of absolute value to that of the exact value. This can be illustrated mathematically by the equation (2) below;
Relative error= absolute error/exact value. --------------------------------------(3).
From equation (2) the solutio to the question is;
Relative error= absolute error/exact value.
Relative error=[ 0.1/0.5] = 0.2.
Relative error Percentage= 0.2×100= 20 Percent.
The metal zirconium becomes superconducting at temperatures below 546 mk. Calculate the temperature at which zirconium becomes superconducting in degrees Celsius. Round your answer to 3 decimal places.
The temperature at which zirconium becomes superconducting in degrees Celsius is approximately 272.85°C.
Explanation:To convert the temperature from millikelvin (mk) to degrees Celsius (°C), we need to use the formula:
T(°C) = T(mk) - 273.15
Applying this formula to the given temperature of 546 mk:
T(°C) = 546 - 273.15 = 272.85°C
Therefore, the temperature at which zirconium becomes superconducting in degrees Celsius is approximately 272.85°C.
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The enzyme urease enhances the rate of urea hydrolysis at pH 8.0 and 20C by a factor of 1014 . If a given quantity of urease can completely hydrolyze a given quantity of urea in 5.0 min at 20 C and pH 8.0, how long would it take for this amount of urea to be hydrolyzed under the same conditions in the absence of urease? Assume that both reactions take place in sterile systems so that bacteria cannot attack the urea.
Answer:
It will take 950 million years for this amount of urea to be hydrolyzed under the same conditions in the absence of urease.
Explanation:
Given that:
In the presence of urease:Urease enhances the rate of hydrolysis by = 10^14
Time taken in hydrolysis is 5 min
In the absence of urease:Time taken in hydrolysis will be = 5 min x 10^14
Now, converting minutes into years
Time = (5 min x 10^14) / (60 min/hr x 24 hr/day x 365 days/year)
Time = 9.50 x 10^8 years
Time = 950 X 10^6 years
Time = 950 million years
Answer:
It would take [tex]5*10^{14}min[/tex] for this amount of of urea to be hydrolysed under the same conditions in the absence of urease.Explanation:
The enzyme increases the rate of urea hydrolysis by a factor of [tex]10^{14}[/tex]
So in absence of enzyme, reaction will take [tex]10^{14}[/tex] times more time for completion.
Therefore time taken,
[tex]\frac{rate catalysed}{rate uncatalysed} = 10^{14}[/tex]
[tex]\frac{t uncatalysed}{t catalysed} = 10^{14}\\\\t uncatalysed = 10^{14} * 5min\\\\t uncatalysed = 5*10^{14}min[/tex]
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An example of a pure substance is ____.
a) an element
b) a compound
c) H2O
d) carbon dioxide
e) all of these
Answer: e) all of these
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water [tex](H_2O)[/tex], carbon dioxide [tex](CO_2)[/tex]
Mixtures are not pure substances as they consist of elements and compounds combined physically and not in any fixed ratio. Example: Air
Thus all given substances are pure substances.
Final answer:
The correct answer to the example of a pure substance is e) all of these, which includes elements, compounds, water (H₂O), and carbon dioxide (CO₂).
Explanation:
An example of a pure substance can be any of the following: a) an element, b) a compound, c) H₂O (which is water, a compound), and d) carbon dioxide (also a compound). Therefore, the correct answer to the question is e) all of these.
A pure substance has a constant composition and characteristic properties. Each element is made up of one type of atom, and cannot be broken down further by chemical means. Examples include carbon and oxygen. On the other hand, a compound is constituted by two or more elements chemically bonded in a fixed ratio, such as water (H₂O) and carbon dioxide (CO₂).
A solution is made by mixing equal masses of methanol, CH 4 O , and ethanol, C 2 H 6 O . Determine the mole fraction of each component to at least three significant figures.
Answer:
Mole fraction of [tex]CH_4O[/tex] = 0.58
Mole fraction of [tex]C_2H_6O[/tex] = 0.42
Explanation:
Let the mass of [tex]CH_4O[/tex] and [tex]C_2H_6O[/tex] = x g
Molar mass of [tex]CH_4O[/tex] = 33.035 g/mol
The formula for the calculation of moles is shown below:
[tex]moles = \frac{Mass\ taken}{Molar\ mass}[/tex]
Thus,
[tex]Moles_{CH_4O}= \frac{x\ g}{33.035\ g/mol}[/tex]
[tex]Moles_{CH_4O}=\frac{x}{33.035}\ mol[/tex]
Molar mass of [tex]C_2H_6O[/tex] = 46.07 g/mol
Thus,
[tex]Moles= \frac{x\ g}{46.07\ g/mol}[/tex]
[tex]Moles_{C_2H_6O}=\frac{x}{46.07}\ mol[/tex]
So, according to definition of mole fraction:
[tex]Mole\ fraction\ of\ CH_4O=\frac {n_{CH_4O}}{n_{CH_4O}+n_{C_2H_6O}}[/tex]
[tex]Mole\ fraction\ of\ CH_4O=\frac{\frac{x}{33.035}}{\frac{x}{33.035}+\frac{x}{46.07}}=0.58[/tex]
Mole fraction of [tex]C_2H_6O[/tex] = 1 - 0.58 = 0.42
When 4.31 g of a nonelectrolyte solute is dissolved in water to make 345 mL of solution at 25 °C, the solution exerts an osmotic pressure of 851 torr.
a. What is the molar concentration of the solution?
b. How many moles of solute are in the solution?c. What is the molar mass of the solute?
Answer:
a) 0.046 mol/L
b) 0.016 mol
c) 271.58 g/mol
Explanation:
A nonelectrolyte solute is a solute that, when dissolved in a solvent, will not make the solution a conductor, and so the electricity will not pass through it. The osmotic pressure is a colligative property, and it's the pressure difference needed to stop the flow of a solution across a semipermeable membrane. It can be calculated by:
π = MRT
Where π is the osmotic pressure, M is the molarity of the solute (mol/L), R is the ideal gas constant, and T is the temperature (in K). For a pressure in torr, R = 62.3637 torr.L/(mol.K).
a) π = MRT , T = 25°C = 298 K
851 = M*62.3637*298
18584.3826M = 851
M = 0.046 mol/L
b) The number of moles of the solute (n) is the molar concentration (molarity) multiplied by the volume. So, for a solution of 345 mL = 0.345 L,
n = 0.046 * 0.345
n = 0.016 mol
c) The molar mass (MM) is the mass divided by the number of moles:
MM = 4.31/0.016
MM = 271.58 g/mol
How many milliliters of 10.0 M HCl ( aq ) are needed to prepare 790.0 mL of 1.00 M HCl ( aq )
Answer:
79.0 mL
Explanation:
Given data
Initial concentration (C₁): 10.0 MInitial volume (V₁): ?Final concentration (C₂): 1.00 MFinal volume (V₂): 790.0 mLIn order to find the volume required of the concentrated solution, we will use the dilution rule.
C₁ × V₁ = C₂ × V₂
V₁ = C₂ × V₂/C₁
V₁ = 1.00 M × 790.0 mL/10.0 M
V₁ = 79.0 mL
Compute the percent ionic character of the interatomic bonds for the following compounds : a. TiO2 b. ZnTe c. CsCld. InSb e. MgCl2
Percent ionic character of bonds is estimated from the electronegativity difference between the bonded atoms - TiO2 has moderate ionic character, ZnTe has low, CsCl has an ionic character, InSb less ionic character and MgCl2 has significant ionic character.
Explanation:The percent ionic character of the bonds in a compound can be estimated based on the electronegativity difference between the bonded atoms. Ionic character increases with the increasing difference in electronegativity, i.e., higher the electronegativity difference, higher the ionic character.
For TiO2, the electronegativity difference between titanium (2.5) and Fluorine (3.8) is 1.3 suggesting moderate ionic character. Similarly, for ZnTe, the electronegativity difference between Zn (1.88) and Te (2.1) would suggest a low ionic character. CsCl, has an electronegativity difference of 1.6 (Cs: 0.79 , Cl: 3.16) suggesting an ionic character. For InSb, between In (2.02) and Sb (1.82), the difference is small, indicating less ionic character. MgCl2 has an electronegativity difference between Mg (1.3) and Cl (3.16) is fairly large, making its bonds significantly ionic.Learn more about Percent Ionic Character here:
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The percent ionic character of a bond is estimated using the difference in electronegativity between the bonded atoms. For the given compounds, the calculated percent ionic characters are: TiO₂ (75%), ZnTe (9.41%), CsCl (75.15%), InSb (4%), and MgCl₂ (59.4%). This demonstrates the varying degrees of ionic versus covalent character in each compound.
The percent ionic character of a bond is determined by the difference in electronegativity between the two atoms involved. Linus Pauling proposed an empirical relation to calculate it:
Determine the electronegativity difference (Δχ) between the two atoms.Use the empirical formula:Percent Ionic Character = 10.16(Δχ)² - 2(57.9 - Δχ)²
Now, let's calculate the percent ionic character for each compound:
1. TiO2
Electronegativity of Ti (Titanium) = 1.54
Electronegativity of O (Oxygen) = 3.44
Δχ = 3.44 - 1.54 = 1.90
Using the formula, Percent Ionic Character = 1-(6-2 × (1.9)^2) x 100 = 75%
2. ZnTe
Electronegativity of Zn (Zinc) = 1.65
Electronegativity of Te (Tellurium) = 2.1
Δχ = 2.1 - 1.65 = 0.45
Using the formula, Percent Ionic Character = 9.41%
3. CsCl
Electronegativity of Cs (Caesium) = 0.79
Electronegativity of Cl (Chlorine) = 3.16
Δχ = 3.16 - 0.79 = 2.37
Using the formula, Percent Ionic Character = 75.15%
4. InSb
Electronegativity of In (Indium) = 1.78
Electronegativity of Sb (Antimony) = 2.05
Δχ = 2.05 - 1.78 = 0.27
Using the formula, Percent Ionic Character = 4%
5. MgCl2
Electronegativity of Mg (Magnesium) = 1.31
Electronegativity of Cl (Chlorine) = 3.16
Δχ = 3.16 - 1.31 = 1.85
Using the formula, Percent Ionic Character = 59.4%
Compare and contrast the positive and negative effects that result from the use of the Haber process.
The Haber process increased agricultural productivity and human support through the large-scale production of fertilizers, but it also enabled the creation of harmful chemical weapons and resulted in environmental issues such as algal blooms and dead zones.
Explanation:The Haber process, developed by Fritz Haber in the early 20th century, had both positive and negative effects. The positive effects of this process include the mass production of nitrogen fertilizers, which increased agricultural productivity and the sustainable support of human populations. An example of this is the jump in the number of humans per hectare that arable land could support, increasing from 1.9 in 1908 to 4.3 by 2008.
However, there are also negative consequences associated with the Haber process. It enabled the creation of harmful chemical weapons during the World War, marking a dark turn in its utilization. Also, the excessive use of nitrogen-based fertilizers, majorly produced through this process, has led to detrimental environmental consequences such as algal blooms, red tides, and dead zones in water bodies. These effects end up destroying marine life and disrupting ecosystems.
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Consider a protein in which a negatively charged glutamic acid side chain (pKa=4.2) makes a salt bridge (ion-ion interaction) with a positively charged histidine side chain (pKa=6.5).
Part A. Do you predict that this salt bridge will become stronger, become weaker, or be unaffected as pH increases from pH=6.9 to pH=7.5?
B. The salt bridge will become weaker.
At pH=6.9, glutamic acid will carry a negative charge. At lower value of pH such as at pH=3 the side chain in the glutamic acid will become fully ionized.In case of Histidine (His) side chain, it will carry a charge grater than +0.5.pH=pKa, the charge on His will be 0.5. Since pH=6.9 above its pka, So it will carry less positive charge and thus become more deprotonated.Further on increasing the pH, glutamic acid side chain will still carry -1 i.e. negative charge, and the charge on Histidine will decrease.Therefore, the salt bridge will become weaker, so option B is correct.
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The salt bridge between glutamic acid and histidine will be unaffected as the pH increases from pH 6.9 to pH 7.5.
Explanation:The salt bridge between glutamic acid and histidine will be unaffected as the pH increases from pH 6.9 to pH 7.5.
Glutamic acid has a pKa of 4.2, meaning that at pH 6.9, the glutamic acid side chain will be in its deprotonated form, which is negatively charged. Histidine has a pKa of 6.5, so at pH 6.9, the histidine side chain will be in its protonated form, which is positively charged.
As the pH increases to 7.5, both glutamic acid and histidine will become less charged, but the relative charges of the two side chains will remain the same, thus the salt bridge between them will be unaffected.
A chemistry student needs 50.00g of acetic acid for an experiment. He has available 450. g of a 31.9%w solution of acetic acid in ethanol. Calculate the mass of solution the student should use
Answer:
The student should use 156.7 g of solution
Explanation:
31.9 %w solution of acetic acid in ethanol means 100 g of solution contains 31.9 g of acetic acid.
So, 450. g of solution contains [tex](\frac{31.9\times 450.}{100})g[/tex] of acetic acid or 143.55 g of acetic acid
Alternatively, 143.55 g of acetic acid is present in 450. g of solution
So, 50.00 g of acetic acid is present in [tex](\frac{450.\times 50.00}{143.55})g[/tex] solution or 156.7 g of solution
Hence the student should use 156.7 g of solution
Light bulbs transform electrical energy to light energy. No energy transformation is 100%. Thus, in the transfer from electrical energy to light energy, some energy is dissipated as heat. The efficiency of an electrical device depends on: 1. how much energy is wasted ‐ transferred to unwanted stores 2. how much energy is transferred to useful stores The more energy a device wastes, the less efficient it is. The graph shows the efficiency of three types of light bulbs: incandescent, fluorescent, and LED. What can you conclude about the energy efficiency of the light bulbs? A) Incandescent light bulbs use less energy than either LED or fluorescent bulbs. B) Fluorescent light bulbs are the most energy efficient since their light and heat energy are most equal. C) Incandescent light bulbs rely on heat energy to process light, increasing the light output while decreasing the heat output. D) LED light bulbs provide more light energy while producing less heat energy, making them the most energy efficient of the three types of bulbs.
LED light bulbs exhibit the highest energy efficiency among incandescent, fluorescent, and LED bulbs due to their ability to produce a significant amount of light energy while minimizing heat energy dissipation.
Looking at the graph, it is evident that LED light bulbs exhibit the highest efficiency among the three types. This conclusion can be drawn from the fact that LED bulbs produce a significant amount of light energy while minimizing heat energy dissipation. LEDs achieve this by converting a higher proportion of electrical energy into visible light, making them more energy-efficient than incandescent and fluorescent counterparts.
On the other hand, incandescent bulbs, characterized by the highest heat output on the graph, are the least efficient. This is because a substantial portion of the electrical energy is transformed into heat, contributing to energy loss rather than useful light output.
The claim that fluorescent bulbs are the most energy-efficient due to a balanced distribution of light and heat is not supported by the graph. While fluorescents fare better than incandescents, they fall short of the high efficiency demonstrated by LED bulbs. Therefore, the correct conclusion is that LED light bulbs provide superior energy efficiency by generating more light energy and less heat energy compared to incandescent and fluorescent alternatives.
How many grams of F− must be added to a cylindrical water reservoir having a diameter of 2.02 × 102 m and a depth of 87.32 m?
Complete Question:
To aid in the prevention of tooth decay, it is recommended that drinking water contain 0.800 ppm fluoride. How many grams of F− must be added to a cylindrical water reservoir having a diameter of 2.02 × 102 m and a depth of 87.32 m?
Answer:
2.23x10⁶ g
Explanation:
The concentration of the fluoride (F⁻) must be 0.800 ppm, which is 0.800 parts per million, so the water must have 0.800 g of F⁻/ 1000000 g of the solution. The density of the water at room temperature is 997 kg/m³ = 997x10³ g/m³. So, the concentration of the fluoride will be:
0.800 g of F⁻/ 1000000 g of the solution * 997x10³ g/m³
0.7976 g/m³
The volume of the reservoir is the volume of the cylinder: area of the base * depth. The base is a circumference, which has an area:
A = πR², where R is the radius = 1.01x10² m (half of the diameter)
A = π*(1.01x10²)²
A = 32047 m²
The volume is then:
V = 32047 * 87.32
V = 2.7983x10⁶ m³
The mass of the F⁻ is the concentration multiplied by the volume:
m = 0.7976 * 2.7983x10⁶
m = 2.23x10⁶ g
Problem Page A chemist measures the amount of bromine liquid produced during an experiment. He finds that of bromine liquid is produced. Calculate the number of moles of bromine liquid produced. Round your answer to significant digits.
The question is incomplete, here is the complete question:
A chemist measures the amount of bromine liquid produced during an experiment. She finds that 766.g of bromine liquid is produced. Calculate the number of moles of bromine liquid produced. Round your answer to 3 significant digits.
Answer: The amount of liquid bromine produced is 4.79 moles.
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
We are given:
Given mass of liquid bromine = 766. g
Molar mass of liquid bromine, [tex](Br_2)[/tex] = 159.8 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of liquid bromine}=\frac{766.g}{159.8g/mol}=4.79mol[/tex]
Hence, the amount of liquid bromine produced is 4.79 moles.
A sample of an ideal gas occupies 2.78 x 10^3 mL at 25°C and 760 mm Hg.
What volume will it occupy at the same temperature and 475 mm Hg?
Answer: It will occupy [tex]4.45\times 10^3ml[/tex] at the same temperature and 475 mm Hg.
Explanation:
Boyle's Law: This law states that pressure is inversely proportional to the volume of the gas at constant temperature and number of moles.
[tex]P\propto \frac{1}{V}[/tex] (At constant temperature and number of moles)
[tex]P_1V_1=P_2V_2[/tex] (At constant temperature and number of moles)
where,
[tex]P_1[/tex] = initial pressure of gas = 760 mm Hg
[tex]P_2[/tex] = final pressure of gas = 475 mm Hg
[tex]V_1[/tex] = initial volume of gas = [tex]2.78\times 10^3ml[/tex]
[tex]V_2[/tex] = final volume of gas = ?
Putting in the values:
[tex]760mm Hg\times 2.78\times 10^3ml=475 mm Hg\times V_2[/tex]
[tex]V_2=4.45\times 10^3ml[/tex]
Thus it will occupy [tex]4.45\times 10^3ml[/tex] at the same temperature and 475 mm Hg
The volume that it will occupy at the same temperature is 4448mL
According to Boyle's law, the pressure of a given mass of gas is inversely proportional to the volume. It is expressed mathematically as:
[tex]P\alpha\frac{1}{V}\\P=\frac{k}{V}\\PV=k[/tex]
This can be expressed as [tex]P_1V_1=P_2V_2[/tex]
Given the following parameters
P₁ = 760mmHg
V₁ = 2.78 x 10³ mL
P₂ = 475mmHg
V₂ = ?
Substitute the given parameters into the formula
[tex]V_2=\frac{P_1V_1}{P_2}\\V_2=\frac{760\times 2780}{475}\\V_2= 4448mL[/tex]
Hence the volume that it will occupy at the same temperature is 4448mL
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a) Show the alkyl bromide and alcohol used to make methyl t-butyl ether using the Williamson ether synthesis to the right of the retrosynthetic arrow.
The alkyl bromide used is Tertiary-Butyl Bromide and the alcohol used is Methanol. The reaction involves reacting Tertiary-Butyl Bromide with Sodium Methoxide to form methyl t-butyl ether and Sodium Bromide as a byproduct.
The alkyl bromide and alcohol used to make methyl t-butyl ether using the Williamson ether synthesis are:
Alkyl Bromide: Tertiary-Butyl Bromide (C4H9Br)
Alcohol: Methanol (CH3OH)
Step 1: React Tertiary-Butyl Bromide (C4H9Br) with Sodium Methoxide (CH3ONa).
Step 2: Heating the reaction mixture will result in the formation of methyl t-butyl ether (MTBE) and Sodium Bromide (NaBr) as byproduct.
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At a certain temperature the vapor pressure of pure heptane C7H16 is measured to be 454.mmHg. Suppose a solution is prepared by mixing 102.g of heptane and 135.g of chloroform CHCl3.
Calculate the partial pressure of heptane vapor above this solution. Be sure your answer has the correct number of significant digits.
Answer:
Mass of heptane = 102g
Vapor pressure of heptane = 454mmHg
Molar mass of heptane = 100.21
No of mole of heptane = mass/molar mass = 102/100.21
No of mole of heptane = 1.0179
Therefore the partial pressure of heptane = no of mole heptane *Vapor pressure of heptane
Partial pressure of heptane = 1.0179*454mmHg
Partial pressure of heptane = 462.1096 = 462mmHg
the partial pressure of heptane vapor above this solution = 462mmHg
The partial pressure of the heptane vapor above the solution is calculated using Raoult's law as 214.5 mmHg.
Explanation:In order to calculate the partial pressure, we will use Raoult's law, which states that the partial pressure of a component in a mixture is equal to the vapor pressure of the pure component multiplied by its mole fraction in the mixture. First, we need to calculate the mole fraction, which is calculated as:
moles of component/total moles in the mixture.
We first need to determine the number of moles of heptane and chloroform, using their respective molecular weights (C₇H₁₆ is approximately 100.21 g/mol, CHCl₃ is about 119.38 g/mol).
Moles of C₇H₁₆ = 102 g / 100.21 g/mol = 1.018 mol
Moles of CHCl₃= 135 g / 119.38 g/mol = 1.131 mol
To determine the mole fraction of the heptane, we take the moles of heptane and divide by the total moles.
X_C₇H₁₆ = 1.018 mol / (1.018 mol + 1.131 mol) = 0.473
Applying Raoult's law, the partial pressure of heptane P_C₇H₁₆ = X_C₇H₁₆ ₓ P(C₇H₁₆, pure) = 0.473 ₓ 454 mmHg = 214.5 mmHg.
So, the partial pressure of heptane vapor above the solution is 214.5 mmHg.
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Ultraviolet radiation and radiation of shorter wavelengths can damage biological molecules because they carry enough energy to break bonds within the molecules. A carbon-carbon bond requires 348 kJ/mol to break.What is the longest wavelength of radiation with enough energy to break carbon-carbon bonds?
Answer:
344 nm is the longest wavelength of radiation with enough energy to break carbon-carbon bonds.
Explanation:
[tex]C-C(g)\rightarrow 2C(g)[/tex] ,ΔH = 348 kJ/mol
Energy required to break 1 mole of C-C bond = 348 kJ
Energy required to break 1 C-C bond = E
[tex]E = \frac{348,000J}{6.022\times 10^{23}}=5.779\times 10^{-19} J[/tex]
Energy related with the wavelength of light is given by Planck's equation:
[tex]E=\frac{hc}{\lambda }[/tex]
[tex]\lambda =\frac{hc}{E}[/tex]
[tex]=\frac{6.626\times 10^{-34} Js\times 3\times 10^8 m/s}{5.779\times 10^{-19} J}[/tex]
[tex]\lambda =3.44\times 10^{-7} m = 344 nm[/tex]
[tex]1 m =10^9 nm[/tex]
344 nm is the longest wavelength of radiation with enough energy to break carbon-carbon bonds.
Ultraviolet radiation and radiation of shorter wavelengths can break carbon-carbon bonds within biological molecules. The longest wavelength that can break carbon-carbon bonds is approximately 1.72 x 10^-6 meters or 1720 nm.
Explanation:Ultraviolet radiation and radiation of shorter wavelengths can damage biological molecules because they carry enough energy to break bonds within the molecules. A carbon-carbon bond requires 348 kJ/mol to break. To find the longest wavelength of radiation with enough energy to break carbon-carbon bonds, we can use the equation E = hc/λ, where E is the energy, h is Planck's constant (6.626 x 10^-34 J·s), c is the speed of light (3.00 x 10^8 m/s), and λ is the wavelength. Rearranging the equation to solve for λ, we get λ = hc/E. Substituting the given energy of 348 kJ/mol (which is equivalent to 348,000 J/mol) and solving for λ, we find that the longest wavelength is approximately 1.72 x 10^-6 meters or 1720 nm.
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Calculate the number of grams of xenon in 4.658 g of the compound xenon tetrafluoride.
Answer:
The mass of xenon in the compound is 2.950 grams
Explanation:
Step 1: Data given
Mass of XeF4 = 4.658 grams
Molar mass of XeF4 = 207.28 g/mol
Step 2: Calculate moles of XeF4
Moles XeF4 = mass XeF4 / molar mass XeF4
Moles XeF4 = 4.658 grams / 207.28 g/mol
Moles XeF4 = 0.02247 moles
Step 3: Calculate moles of xenon
XeF4 → Xe + 4F-
For 1 mol xenon tetrafluoride, we have 1 mol of xenon
For 0.02247 moles XeF4 we have 0.02247 moles Xe
Step 4: Calculate mass of xenon
Mass xenon = moles xenon * molar mass xenon
Mass xenon = 0.02247 moles * 131.29 g/mol
Mass xenon = 2.950 grams
The mass of xenon in the compound is 2.950 grams
To calculate the number of grams of xenon in 4.658 g of xenon tetrafluoride, we need to determine the molar mass of XeF4 and convert grams to moles. The molar mass of XeF4 is 207.282 g/mol. Using this molar mass, we find that there are 0.0225 moles of XeF4, which corresponds to 2.968 grams of xenon.
Explanation:To calculate the number of grams of xenon in 4.658 g of xenon tetrafluoride, we need to first determine the molar mass of xenon tetrafluoride (XeF4) and then use it to convert grams to moles. The molar mass of XeF4 is calculated as follows:
Molar mass of Xe = 131.293 g/mol
Molar mass of F = 18.998 g/mol
Molar mass of XeF4 = (131.293 g/mol) + 4 * (18.998 g/mol) = 207.282 g/mol
Now, we can use the molar mass to convert grams to moles:
Moles of XeF4 = (4.658 g) / (207.282 g/mol) = 0.0225 mol
Finally, we can convert moles of XeF4 to grams of xenon:
Grams of xenon = (0.0225 mol) * (131.293 g/mol) = 2.968 g
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A chemist adds 180.0 mL of a 1.42M sodium carbonate (Na CO,) solution to a reaction flask. Calculate the millimoles of sodium carbonate the chemist has added to the flask. Round your answer to 3 significant digits. mmol
Answer: The millimoles of sodium carbonate the chemist has added to the flask are 256
Explanation:
Molarity is defined as the number of moles dissolved per liter of the solution.
To calculate the number of moles for given molarity, we use the equation:
[tex]\text{Molarity of the solution}=\frac{\text{milli moles of solute}}{\text{Volume of solution in ml}}[/tex] .....(1)
Molarity of [tex]BaCl_2[/tex] solution = 1.42 M
Volume of solution = 180.0 mL
Putting values in equation 1, we get:
[tex]1.42M=\frac{\text{milli moles of }BaCl_2}{180.0ml}\\\\\text{milli moles of }BaCl_2}={1.42M\times 180.0ml}=256milli mol[/tex]
Thus the millimoles of sodium carbonate the chemist has added to the flask are 256.
In order to calculate the millimoles of sodium carbonate added to the flask, one must rearrange the formula for molarity, convert the volume from milliliters to liters, substitute, solve, then, finally, convert the solution from moles to millimoles. This results in an approximate 255.6mmol of sodium carbonate.
Explanation:The chemist added 180.0 mL of a 1.42M sodium carbonate (Na2CO3) solution. Molarity (M) is defined as the number of moles of solute (Na2CO3 in this case) per liter of solution. Therefore, to find the number of millimoles, you would use the equation:
M = moles/volume(L)
Rearrange the formula to solve for moles:
moles = M x volume (L)
Next, convert the volume from milliliters to liters: 180.0 mL = 0.180 L. Substituting into the equation gives:
moles = 1.42M x 0.180 L = 0.2556 moles
To convert moles to millimoles, you'll need to know that 1 mole = 1000 millimoles. Therefore, 0.2556 moles x 1000 = 255.6 millimoles rounded to three significant digits.
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In the Minnesota Department of Health set a health risk limit for methanol in groundwater of 4.00 μg. Suppose an analytical chemist receives a sample of groundwater with a measured volume of 76.0 mL.
Calculate the maximum mass in milligrams of methanol which the chemist could measure in this sample and still certify that the groundwater from which it came met Minnesota Department of Health standards. Be sure your answer has the correct number of significant digits.
The question is incomplete, here is the complete question:
In the Minnesota Department of Health set a health risk limit for methanol in groundwater of 4.00 μg/L. Suppose an analytical chemist receives a sample of groundwater with a measured volume of 76.0 mL.
Calculate the maximum mass in milligrams of methanol which the chemist could measure in this sample and still certify that the groundwater from which it came met Minnesota Department of Health standards. Be sure your answer has the correct number of significant digits.
Answer: The risk limit of methanol in the given amount of methanol is [tex]3.04\times 10^{-4}mg[/tex]
Explanation:
We are given:
Risk limit for methanol in groundwater = 4.00 μg/L = 0.004 mg/L (Conversion factor: [tex]1mg=1000\mu g[/tex] )
Volume of groundwater that is to be measured = 76.0 mL
We know that:
1 L = 1000 mL
Applying unitary method:
In 1000 mL of groundwater, the risk limit of methanol is 0.004 mg
So, in 76.0 mL of groundwater, the risk limit of methanol will be = [tex]\frac{0.004}{1000}\times 76.0=3.04\times 10^{-4}mg[/tex]
Hence, the risk limit of methanol in the given amount of methanol is [tex]3.04\times 10^{-4}mg[/tex]
Calculate the density, in grams per liter, of carbon dioxide (CO2) gas at STP.
Answer:
Density of CO₂ at STP = 1.96 g/L
Explanation:
1 mol of any gas at STP occupies 22.4L of volume.
The rule for the Ideal gases.
Assume 1 mol of CO₂, we know that has 44 grams of mass.
Density = mass / volume
44 g/ 22.4L = 1.96 g/L
Answer: 1.96g/L
Explanation:
1mole of CO2 contains 22.4L at stp.
1mole of CO2 = 12 + ( 2x16) = 12 + 32 = 44g
Density = Mass /volume
Density = 44g /22.4L
Density = 1.96g/L
A 17.0 g sample of quartz, which has a specific heat capacity of 0.730 Jg , is dropped into an insulated container containing 200.0 g of water at 85.0 °C and a constant pressure of 1 atm. The initial temperature of the quartz is 7.2 ℃. Assuming no heat is absorbed from or by the container, or the surroundings, calculate the equilibrium temperature of the water. Be sure your answer has 3 significant digits. ec
Answer:
the final temperature T final = 83.863 °C
Explanation:
Assuming that no heat is absorbed from the container , then all the heat absorbed by the water Q water comes from the heat released by the quartz (-Q quatz), since
Q water + Q quatz = Q surroundings =0
denoting w as water and q as quartz then
Q water = mw * cpw * (Tfinal - T initial w)
Q quartz = mq * cpq * (Tfinal - T initial q)
where
m= mass
cp= specific heat capacity at constant pressure
T final = final temperature
T initial w and T initial q = initial temperature of water and quartz respectively
then
mw * cpw * (Tfinal - T initial w) + mq * cpq * (Tfinal - T initial q) = 0
mw * cpw * Tfinal + mq * cpq * Tfinal = mw * cpw *T initial w + mq * cpq * T initial q
Tfinal = (mw * cpw *T initial w+ mq * cpq * T initial q)/(mw * cpw +mq * cpq)
replacing values and assuming cpw= 1 cal/gr°C = 4.186 J/g°C
Tfinal = (200 g * 4.186 J/g°C * 85 °C + 17g * 0.730 J/g°C * 7.2 °C)/(200 g * 4.186 J/g°C + 17g * 0.730 J/g°C) = 83.863 °C
Tfinal = 83.863 °C