Answer:
E. 16.6 mol HCl
Explanation:
The equation for the reaction is;
Zn + 2 HCl --> ZnCl2 + H2
From the reaction 2 moles of HCl produces 1 mole of ZnCl2
Therefore; 8.3 moles of ZnCl2 will be produced by;
= 8.3 moles ×2
= 16.6 Moles of HCl
Therefore; E. 16.6 mol HCl
when a 12.8 g sample of KCL dissolves in 75.0 g of water in a calorimeter the temp. drops from 31 Celsius to 21.6 Celsius. Calculate deltaH for the process.
PLEASE EXPLAIN EVERY STEP.
To calculate the delta H for the dissolution of KCl in water, use the heat equation q = mcΔT with the given mass, specific heat capacity of water, and the temperature change. Then, convert q to kilojoules and divide by the number of moles of KCl to find the enthalpy change per mole.
Explanation:The question pertains to thermochemistry, a branch of chemistry that deals with the heat involved in chemical reactions and physical transformations. We need to calculate the enthalpy change (delta H) when KCl dissolves in water, which involves using the formula q = mcΔT, where q is the heat absorbed or released, m is the mass of the solvent (water), c is the specific heat capacity, and ΔT is the change in temperature.
First, we identify the temperature drop: ΔT = 21.6°C - 31.0°C = -9.4°C. This indicates that the solution absorbed heat (since the temperature of the water dropped, the reaction is endothermic). Then, using the specific heat capacity of water (4.18 J/g°C), we calculate q as follows:
q = mcΔT
= (75.0 g)(4.18 J/g°C)(-9.4°C)
= -2969.4 J
Since specific heat capacity and mass are both positive, the negative q value signifies that the heat was absorbed by the substance from the water. To find delta H in kJ/mol, we convert the mass of KCl to moles using its molar mass (74.55 g/mol) and then divide q by the number of moles:
Moles of KCl = 12.8 g / 74.55 g/mol
Approximately = 0.172 moles
Delta H = q / moles
= -2969.4 J / 0.172 mol
= -17261 J/mol
Since we need delta H in kilojoules per mole, we convert J to kJ:
Delta H = -17261 J/mol / 1000 J/kJ
= -17.261 kJ/mol
As the delta H is negative, it confirms that the dissolution of KCl in water is an endothermic process.
Which of the following is not true in regard to noble gases? A. These elements have full outermost shells. B. These elements are found in the last column (Group 18) on the periodic table. C. These elements tend to be relatively inactive. D. These elements tend to gain or lose electrons easily
Answer:
D.These elements tend to gain or lose electrons easily is incorrect.
Explanation:
Noble gasses consist of atoms that have full rings of electrons. Electrons are what bond atoms together to create chemical compounds, and incomplete rings are needed for the process.
D. These elements tend to gain or lose electrons easily
Explanation:The gases which are considered as Nobel are generally nonreactive. Truth be told, they are the least responsive components on the periodic table. This is on the grounds that they have a total valence shell. They tend to pick up or lose electrons rarely.
In 1898, Hugo Erdmann begat the expression “Nobel gas” to mirror the low reactivity of these components, similarly as the respectable metals are less receptive than different metals. These gases have high energies of ionization and immaterial electronegativities. These gases have low breaking points and are on the whole gases at room temperature.
All man-made and most carbon-based compunds are___ . 1. organic 2.inorganic
Answer:
2. Inorganic
Explanation:
All man-made and most carbon-based compounds are inorganic
Answer:
inorganic
Explanation:
You are experimenting on the effect of temperature on the rate of reaction between hydrochloric acid (HCl) and potassium iodide (KI). When the reaction is completed at 400K there are approximately 250,000 collisions per mole of reactant. You run the experiment again at 150K. Which of the following would you expect to be the number of collisions recorded at 150K
A. 0
B. 400,000
C. 250,000
D. 15,000
Answer:
D. 15,000.
Explanation:
Kinetic energy of the molecules (of the reactants) is directly proportional to its temperature according to the relation:KE = (3/2)KT
Where, KE is the kinetic energy of the molecules (J),
K is the Boltzmann constant (1.381 × 10⁻²³ J/K),
T is the temperature (K)
The KE (energy of motion of the molecules) can be expressed as the collisions per mole of reactant.When temperature increases, the collisions per mole of reactant and then the kinetic energy increases.In this problem, at 400 K there are approximately 250,000 collisions per mole of reactant. So, at 150 K, the KE will decrease and also the collisions per mole of reactant will decrease. It is also impossible, for the collisions per mole of reactant, to be zero at this T (150 K).So, the right choice is: D. 15,000
Answer: D. 15,000.
Explanation: Founders Educere answer. And whatever that dude said^
A solution is prepared by dissolving 20.1 g of MgCl2 with the addition of 157.0 mL of water (density of water is 1.00g/cm3). The density of the resulting solution was determined to be 1.089g/cm3. Calculate the molar concentration of this solution: Hint: Make sure you understand the definition on Molar concentration
Answer:
1.3 M.
Explanation:
We need to calculate the mass of the solution:mass of the solution = mass of MgCl₂ + mass of water
mass of MgCl₂ = 20.1 g.
mass of water = d.V = (157.0 mL)(1.0 g/cm³) = 157.0 g.
∴ mass of the solution = mass of MgCl₂ + mass of water = 20.1 g + 157.0 g = 177.1 g.
Now, we can get the volume of the solution:V of the solution = (mass of the solution)/(density of the solution) = (177.1 g)/(1.089 g/cm³) = 162.62 mL = 0.163 L.
Molarity is the no. of moles of solute dissolved in a 1.0 L of the solution.
M = (no. of moles of MgCl₂) / (Volume of the solution (L)).
∴ M = (mass/molar mass)of MgCl₂ / (Volume of the solution (L)) = (20.1 g/95.211 g/mol) / (0.163 L) = 1.29 M ≅ 1.3 M.
What is the change in electrons for sulfur in the following reaction?
S + NO3 - -> SO2 + NO
A. Lose 4 electrons
B. Lose 2 electrons
C. Gain 4 electrons
D. Gain 2 electrons
Answer:
A. Lose 4 electrons
Explanation:
The reaction equation is given as:
S + NO₃ → SO₂ + NO
The half equation of the reaction for S:
S → SO₂
For S to go into SO₂,
we move from an oxidation state of 0 to +4,
Finding the oxidation state of S in SO₂
a + (-2 x 2) = 0
a - 4 = 0
a = 4
This is a loss of 4 electrons
Answer:
Lose 4 electrons
Explanation:
Answer for Educere/ Founder's Education
8. What is the force of gravity on a dog in a space suit that's running around on the moon? The dog's body has a mass of 20 kilograms. Round to the nearest hundredth place. A. 196 N B. 1,176 N C. 2 N D. 32.67 N
Answer:
D. around 32 N.
Given that:
The mass of the moon is approximately [tex]7.348\times 10^{22}\;\text{kg}[/tex], and The (mean) radius of the moon is approximately [tex]1.7371\times 10^{6}\;\text{m}[/tex].Explanation:
The dog is much smaller and lighter than the moon; it behaves like a point mass. Consider the equation for the size of gravity between a spherical mass and a point mass outside that spherical mass:
[tex]\displaystyle F = \frac{G\cdot M \cdot m}{r^{2}}[/tex],
where
[tex]F[/tex] is the size of gravity,The gravitational constant [tex]G \approx 6.67\times 10^{-11}\;\text{kg}^{-1}\cdot \text{m}^{-1}\cdot \text{s}^{-2}[/tex],[tex]M[/tex] is the mass of the sphere, [tex]m[/tex] is the size of the point mass, and[tex]r[/tex] is the separation between the point mass and the center of mass of the sphere.The dog is at the surface of the moon. As a result, the [tex]r[/tex] shall be the same as the radius of the moon. Make sure all values are in SI units (kilograms and meters.) Apply the formula:
[tex]\displaystyle \begin{aligned}F &= \frac{G\cdot M \cdot m}{r^{2}} \\ &= \frac{(6.67\times 10^{-11})\times(7.348\times 10^{22})\times 20}{(1.7371\times 10^{6})^{2}}\\&= 32.48\;\text{N}\end{aligned}[/tex].
This value may vary slightly depending on the position of the dog on the moon.
Weight = (mass) x (acceleration of gravity)
Gravity on or near the moon's surface = 1.63 m/s^2
Dog's weight = (20 kg) x (1.63 m/s^2)
Weight = 32.6 Newtons (D)
If you are given a chemical equation and specific amounts for each reactant in grams, how would you determine how much product can possibly be made? If you are given a chemical equation and specific amounts for each reactant in grams, how would you determine how much product can possibly be made? 1. Determine which reactant is the limiting reactant. 2. Using conversion factor, convert grams of the limiting reactant to grams of the product. 1. Determine which reactant is the limiting reactant. 2. Convert each reactant into moles of the product. 3. Convert the moles of product, from the limiting reactant, to grams. 1. Convert each reactant into moles of the product. 2. Determine which reactant is the limiting reactant. 3. Convert the moles of product, from the limiting reactant, to grams.
Answer:
If you are given a chemical equation and specific amounts for each reactant in grams, you have to follow these steps, in order, to determine how much product can possilby be made:
1. Convert each reactant into moles of the product. 2. Determine which reactant is the limiting reactant. 3. Convert the moles of product, from the limiting reactant, to grams.Justification:
The balanced chemical equation, through the coefficients, represents the proportions, in terms of mole ratios, in that each reactant chemically react with each other to form each product.
So, if you are given specific aomunts for each reactant in grams, you must start by converting each reactant amount into mole numbers, using the molar mass of each one.
Then, using the theoretical mole ratios (from the coefficients of the balanced chemical equation) you can determine how much of each product can be produced, in terms of moles, first starting with the complete consumption of one of the reactants, and then doing the same with each of the other reactants, one by one.
The reactant that yields the least amount of product is the limiting reactant, since it will be consumed completely once that amount of product is obtainded, while the other reactants will be in excess.
Now, that you have the number of moles that can be produced from the limiting reactant, you can convert it into grams of product, just using the molar mass of the same.
Final answer:
To determine how much product can be made from given amounts of reactants, balance the chemical equation, convert reactant masses to moles, identify the limiting reactant, calculate the moles of product, and then convert these moles to grams.
Explanation:
When given a chemical equation and specific amounts of reactants in grams, the steps to determine how much product can be made are as follows:
Balance the chemical equation for the reaction.Convert the given reactant masses into moles using their molar masses.Compare the calculated mole ratios to the mole ratios in the balanced equation to determine the limiting reactant.Use the moles of the limiting reactant to calculate the moles of product that can be formed.Convert these moles of product back into grams.To identify the limiting reactant, a key point to remember is that it's the reactant that yields the lesser amount of product when the moles of each reactant are individually compared to the moles of product dictated by the balanced equation. This concept applies whether we calculate the number of moles or the final mass of the product.
If a neutral atom becomes positively charged, it has undergone _________.
A. oxidation
B. catalyzation
C. None of these
D. redox
If a neutral atom becomes negatively charged, it has undergone reduction.
Reduction is the process through which a neutral atom gain an electron (thus reducing its oxidation number) and turns into a negative ion (also known as : anion)
So basically none of the above
If a neutral atom becomes negatively charged, it has undergone reduction. Hence, option C is correct.
What are atoms?An atom contains a central nucleus surrounded by one or more electrons.
Protons are bound in the nucleus and can be neither gained nor lost. So any change in the charge of an atom is due to changes in its electron count. If a neutral atom gains electrons, then it will become negatively charged. If a neutral atom loses electrons, then it becomes positively charged.
The loss of electrons is the corresponding increase in the oxidation state of a given reactant is called oxidation. The gain of electrons and the decrease in the oxidation state of a reactant is called reduction.
Reduction is the process through which a neutral atom gains an electron (thus reducing its oxidation number) and turns into a negative ion (also known as an anion).
Hence, option C is correct.
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Please HELP, the question is attached.
Try this solution, all the details are described in the attached picture.
What is a nonpolar covalent bond?
A.
a bond between two nonmetal atoms
B.
a bond in which electrons are shared unequally
C.
a bond with ΔEN greater than 0.5
D.
a bond between two atoms that have equal electronegativities
Reset
Answer: The correct answer is Option D.
Explanation:
A non-polar covalent bond is defined as the bond which is formed between the atoms having no difference in electronegativity values. For Example: [tex]Cl_2,H_2[/tex] etc..
In this bond, the electrons are shared equally and [tex]\Delta EN[/tex] value is equal to 0.
Hence, the correct answer is Option D.
The correct answer is D. A nonpolar covalent bond is a type of covalent bond where electrons are shared equally between two atoms due to equal electronegativities.
The equal sharing occurs because the atoms have identical or nearly identical electronegativity values, meaning neither atom attracts the shared electrons more than the other. An example of a nonpolar covalent bond can be found in a molecule of chlorine, where both chlorine atoms share the electrons equally.
Which of the following data tables correctly shows how temperature affects the reaction between sodium thiosulfate and hydrochloric acid?
a because as temperature increases, reaction rate increases.
Answer:
The correct answer is the table of point A.
Explanation:
An increase in temperature increases the speed of reaction, regardless of whether the reaction is endothermic or exothermic. This is because as the temperature increases, the number of molecules with an energy equal to or greater than the activation energy increases, thus increasing the number of effective shocks.
Have a nice day!
*URGENT*
Which of the following is true about an ionic compound?
a. the chemical formula shows the atoms in a molecule
b. the formula unit gives the number of each type of ions in a crystal
c. it is composed of anions and cations and yet it is electronically neutral
d. the chemical formula shows the ions in a molecule
Answer:
c hopes this helps u pass or whatever
An ionic compound has a chemical formula that shows the ions in a molecule.
Ionic compounds are held by the electrostatic attraction between the atoms. The ionic compounds are formed by ions of different charges.
(a) The chemical formula of ionic compounds has a number subscript which indicates the number of atoms of the ion.
(b) The formula unit does not give the number of ions.
(c) The ionic compounds are not necessarily neutral as the charge difference between anion and cation results in the charged compound.
(d) The chemical formula of an ionic compound represents the ions in a molecule.
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In order for a liquid particle to become a gas it must: (choose all that apply)
1.overcome the attractive forces of other liquid particles
2.overcome the attractive forces of other gas particles
3.gain energy
4.lose energy
Answer:
1.overcome the attractive forces of other liquid particles
3.gain energy
Explanation:
A phase change from liquid to solid occurs when heat energy is added to the system. The heat energy gives the liquid molecules more kinetic energy and the attractive forces between the particles are overcome. When the molecules of liquid gains sufficient energy, they are free to move in all directions that they want, thus becoming gases.
Explanation:
In liquids, the molecules are held by less strong intermolecular forces of attraction as compared to solids. Due to which they are able to slide past each other. Hence, they have medium kinetic energy.
On the other hand, in gases, the molecules are held by weak Vander waal forces. Hence, they have high kinetic energy due to which they move rapidly from one place to another leading to more number of collisions.
Hence, gases are able to expand more rapidly as compared to liquids.
Therefore, we can conclude that in order for a liquid particle to become a gas it must:
overcome the attractive forces of other liquid particles.gain energy.6. Newton's First Law of motion addresses a body at rest or in motion. What is inertia's role in Newton's First Law of Motion? A. It determines how much mass the object retains. B. It's associated with the acceleration of the object. C. It's the tendency for the body to change motion quickly. D. It's the tendency for the body to resist a change in motion
Answer: The correct answer is "It's the tendency for the body to resist a change in motion".
Explanation:
Newton's First Law of motion addresses a body at rest or in motion. This law is also known as "Law of inertia".
Inertia resists any change in the state of the object. Mass is a measure of inertia.
If the object is in motion then it remains in this state or if the object is at rest then it remains in this state unless the external force is applied.
If the object is moving with constant velocity then it will remain moving with this velocity unless it is accelerated.
Suppose, bus driver applies suddenly applies brake. The passenger sitting inside the bus falls forward. It is due to inertia. As the passenger does not want to change its state. It resists this change. The upper part of the body wants to remain in the state of motion. It's the tendency for the body to resist a change in motion
Therefore, the correct option is (D).
Sodium and chlorine combine to form table salt, also called sodium chloride. Sodium chloride is a(n) A. atom. B. element. C. compound. D. mixture
Answer:
C. Compound
Explanation:
NaCl is a combination of two elements. This is specifically an ionic compound.
Sodium chloride is a compound.
What is a compound?A chemical compound exists as a chemical substance comprised of many identical molecules composed of atoms from more than one component held together by chemical bonds. Compounds exist as chemical substances made up of two or more elements that exist chemically bound together in a fixed ratio. All the subject in the universe is composed of atoms of more than 100 various chemical elements, which exist found both in pure form and incorporated into chemical compounds. Chemical compounds exist formed by elements that bond together. These bonds stand generally covalent, ionic, or metallic bonds.
The correct solution is option C.
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Why is chlorine gas a product of NaCl electrolysis?
A. The Cl- ions become oxidized at the cathode allowing them to form Cl2 molecules.
B. The Cl+ ions become reduced at the anode allowing them to form Cl2 molecules.
C. The Na+ ions react to the anode, releasing the Cl- ions with enough energy to change into a gas.
D. The Na- ions react to the cathode, releasing the Cl+ ions with enough energy to change into a gas.
Answer:
A. The Cl- ions become oxidized at the cathode allowing them to form Cl2 molecules.
Explanation:
At the anode in an electrolytic cell oxidation occurs.
In the electrolysis of NaCl, at the anode both Cl⁻ and OH⁻ migrates here.
Cl⁻ is preferentially discharged and it undergoes oxidation as shown below:
2Cl⁻ → Cl₂ + 2e⁻
We see a loss of electron and change in oxidation number of Cl from -1 to 0
Chlorine gas is liberated in this electrode.
Answer:
The Cl- ions become oxidized at the cathode allowing them to form Cl2 molecules.
Explanation:
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When marble chips are placed into an acidic solution, the mass of the marble decreases as it reacts with the acid and is stripped away. Large marble chips have been recorded to lose 2 grams of mass over 7 minutes. Which of the following best describes how small chips would react to the same acid?
A. The small chips would react more slowly and would have a lower net loss. They would lose 1 gram over the 7 minutes, and would not lose more mass if left for a longer time.
B. The small chips would react faster, losing 2 grams over 3.5 minutes and then
staying constant, not losing any more mass, for the remainder of the time.
C. The small chips would react faster, losing 4 grams over the same 7 minutes.
D. The small chips have less mass and would react more slowly, losing 2 grams over 14 minutes.
Final answer:
Smaller marble chips react faster with acid due to the increased surface area, leading to a greater loss of mass in the same time frame compared to larger chips. Hence, the best description is that small chips would lose 4 grams over 7 minutes (option C).
Explanation:
When considering the reaction of marble chips with acid, the rate at which the reaction occurs depends largely on the surface area of the marble that is exposed to the acid. Smaller chips have a larger surface area relative to their volume, allowing more acid to come into contact with the chips, thus increasing the rate of the reaction. Marble (Ca[tex]CO_{3}[/tex]) reacts with hydrochloric acid (HCl) to form calcium chloride, water, and carbon dioxide gas. As the reaction proceeds, the mass of the marble decreases because carbon dioxide gas is released and escapes into the air.
Based on this explanation, option C is the best description of how small chips would react: The small chips would react faster, losing 4 grams over the same 7 minutes. This is because the small chips provide a greater surface area for the acid to react with, leading to a faster reaction rate and therefore a greater loss of mass in the same amount of time compared to larger chips.
How many protons and electrons are present in O²⁻?a) 8 protons and 8 electrons b) 10 protons and 8 electrons c) 8 protons and 10 electrons d) 16 protons and 8 electrons e) none of the above
Answer:
c) 8 protons 10 electrons
Because there would usually be 8 of both, but in this case there has to be 2 more electrons to give it the ²⁻ charge
Use the following equation to determine the charge on iron when it dissociates from oxygen and determine whether it is being oxidized or reduced:
Fe2O3 + 3CO -> 2Fe + 3CO2
A. It starts with a charge of +3 and is reduced.
B. It starts with a charge of +2 and is reduced.
C. It starts with a charge of -2 and is oxidized.
D. It starts with a charge of -3 and is oxidized.
The correct answer is A. Brainliest would be much appreciated.
The oxidation state of [tex]Fe_2O_3[/tex] is +3. The bond formation between oxygen and iron depends on the difference in electronegativity between these two atoms. It starts with a charge of +3 and is reduced. Hence, option A is correct.
What is the oxidation number?The total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.
Oxygen in nearly all cases has a charge of 2−, so the total ionic charge the O atoms exhibit is 3(−2)=−6 .
If two Fe atoms equalize this charge and make it neutral, the charge (oxidation state) of Fe in this compound must be 3+.
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Consider the total ionic equation below.
2H+ + CrO2 3- + Ba2+ + 2oh- → Ba2+ + CrO2 4- + 2H2O
What are the spectator ions in this equation?
Answer:
[tex]\boxed{\text{Ba}^{2+}}[/tex]
Explanation:
[tex]\rm 2H^{+} + CrO_{2}^{3-} + \textbf{Ba}^{2+} + 2OH^{-} \longrightarrow \textbf{Ba}^{2+} + CrO_{2}^{4-} + 2H_{2}O[/tex]
The spectator ions are the ions that are on both sides of the equation.
[tex]\text{In this equation, the spectator ions are }\boxed{\textbf{Ba}^{2+}}.[/tex]
They are present at the beginning and at the end of the reaction. They don't take part in the reaction. They are simply "spectators" watching the other ions "do their thing."
Spectator ions remain unchanged during a chemical reaction and are crucial in identifying the net ionic equation.
When looking at the total ionic equation 2H+ + CrO2 3- + Ba2+ + 2OH-
ightarrow Ba2+ + CrO2 4- + 2H2O, spectator ions are those that do not participate in the reaction and are present in the same form on both the reactant and product sides of the equation. In this case, the Barium ion (Ba2+) is the spectator ion since it does not change from reactants to products.
Spectator ions are ions that do not participate in a chemical reaction and remain unchanged during the reaction. They can be identified by observing which ions are present on both sides of the equation with the same coefficients. By canceling out the spectator ions, you can obtain the net ionic equation, which focuses only on the species directly involved in the reaction.
To determine the ammonia concentration in a sample of lake water, three samples are prepared. In sample A, 10.0 mL of lake water is mixed with 5 mL of phenol solution and 2 mL of sodium hypochlorite solution, and diluted to 25.0 mL in a volumetric flask. In sample B, 10.0 mL of lake water is mixed with 5 mL of phenol solution, 2 mL of sodium hypochlorite solution, and 2.50 mL of a 5.50×10−4 M ammonia solution, and diluted to 25.0 mL. Sample C is a reagent blank. It contains 10.0 mL of distilled water, 5 mL of phenol solution, and 2 mL of sodium hypochlorite solution, diluted to 25.0 mL. The absorbance of the three samples is then measured at 625 nm in a 1.00 cm cuvet. The results are shown in the table.Sample Absorbance (625 nm)A 0.419B 0.666C 0.045What is the molar absorptivity (????) of the indophenol product?????=M−1cm−1What is the concentration of ammonia in the lake water?[NH3]lake water=M
Answer:Sample Absorbance (625 nm)
A 0.536
B 0.783
C 0.045
Therefore, I will use these data to solve your question. If you have other absorbances values, just follow my steps and plug in different numbers.
First, we see 1 mole of NH3 gives 1 mole product.
In B moles of NH3 = moles of NH3 in A + (5.5 x10^-4 x2.5/1000) = 1.375 x10^6 + mA
( mA = moles of NH3 in A) vol of B = 25 = vol of A
now A = el C = eC ( since l = 1cm)
Because, n net absorbance due to complex blank absorbance must be removed.
Here A(A) = 0.536 - 0.045 = 0.491 , A(B) = 0.783 - 0.045 = 0.738
(you can plug in different numbers in this step)
A2/A1 = C2/C1 , A(B)/A(A) = (1.375x10^-6 +mA)/(mA) = 0.738/0.491
So, mA = 2.733 x 10^-6 = moles of NH3 in A (Lake water)
Hence [NH3] water ( 2.733 x10^-6 ) x 1000/25 = 1.093 x 10^-4 M
Lake water vol = 10 ml out of 25,
Concentration of ammonia in lake water = 2.733 x10^-6 x 1000/10 = 2.733 x 10^-4 M
Then, A = 0.491 = e x 1 x 1.093 x10^-4
e = 4492 M-1cm-1
Explanation:
The molar absorptivity (ε) of the indophenol product, as calculated using the Beer-Lambert law and the known concentration and measured absorbance of Sample B, is 12109.09 M^-1 cm^-1. To find the concentration of ammonia in the lake water, we subtract the absorbance of the reagent blank from the absorbance of Sample A, then use the Beer-Lambert law to solve for the concentration. It results in 0.000031 M, or 3.1x10^-5 M.
Explanation:To find the molar absorptivity (ε), we can use the Beer-Lambert law, which states that the absorbance (A) of a solution is directly proportional to its concentration (c) and the path length (l) through which the light passes. The formula is A = εlc. In this case, the path length is a constant 1.00 cm, so we can rearrange the formula to solve for ε: ε = A / (l * c).
Sample B contains a known amount of NH3. From this, we know that the concentration of NH3 in the solution is (2.50 mL * 5.50x10^-4 M) / 25 mL = 0.000055 M. Using the measured absorbance for sample B (0.666), we can solve for ε: ε = 0.666 / (1.00 cm * 0.000055 M) = 12109.09 M^-1 cm^-1.
To find the concentration of ammonia in the lake water, we subtract the absorbance of the reagent blank (C) from the absorbance of sample A, which contains an unknown amount of NH3. This gives us the absorbance due to the NH3 in the lake water: A' = 0.419 - 0.045 = 0.374. We can then use the Beer-Lambert law to solve for the concentration of NH3: [NH3] = A' / (ε * l) = 0.374 / (12109.09 M^-1 cm^-1 * 1.00 cm) = 0.000031 M, or 3.1x10^-5 M.
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What are dispersion forces
are a type of force acting between atoms and molecules.[1] They are part of the van der Waals forces. The LDF is named after the German-American physicist Fritz London.
First of all, disperse means to break away.
So dispersion forces are forces that cause molecules to break away from each other. Dispersion forces are a very very weak force because the molecules are not attracted to each other because they disperse or move away.
A certain radioactive element has a half-life of one hour. If you start with 20.0 grams of the element at noon, how much of the radioactive element will be left at 3 p.m.?
a. 10.0 grams b. 5.0 grams c. 2.5 grams d. 1.25 grams
your answer should be C.
MARK ME BRAINLIEST PLEASE!
Answer: The correct answer is Option c.
Explanation:
All the radioactive reactions follows first order kinetics.
The equation used to calculate half life for first order kinetics:
[tex]t_{1/2}=\frac{0.693}{k}[/tex]
We are given:
[tex]t_{1/2}=1hr[/tex]
Putting values in above equation, we get:
[tex]k=\frac{0.693}{1}=0.693hr^{-1}[/tex]
Rate law expression for first order kinetics is given by the equation:
[tex]k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}[/tex]
where,
k = rate constant = [tex]0.693hr^{-1}[/tex]
t = time taken for decay process = 3.00 pm - 12.00 pm = 3 hour
[tex][A_o][/tex] = initial amount of the reactant = 20 g
[A] = amount left after decay process = ?
Putting values in above equation, we get:
[tex]0.693hr^{-1}=\frac{2.303}{3hr}\log\frac{20}{[A]}[/tex]
[tex][A]=2.5g[/tex]
Hence, the correct answer is Option c.
Which of the following statements is true of vibrations? A. The frequency of infrasonic vibrations is much too high to be heard by humans. B. Infrasonic vibrations are used in sonar equipment and to detect flaws in steel castings. C. Ultrasonic vibrations have a frequency lower than the range for normal hearing. D. Neither ultrasonic nor infrasonic vibrations can be heard by humans
D. ( Neither ultrasonic nor infrasonic vibrations can be heard by humans. )
Answer:
The correct statement is option D, that is, neither ultrasonic nor infrasonic vibrations can be heard by humans.
Explanation:
The ultrasonic vibrations are the sound waves exhibiting the frequency of more than 20000 Hz, whereas the upper-frequency limit in human beings is about 20 Hz. Humans cannot hear the ultrasound as it is more than 20 Hz.
On the other hand, the infrasonic vibrations refer to a low-frequency sound, it is lower in frequency in comparison to 20 Hz, that is, the usual limit of human hearing. Thus, for humans to perceive infrasound, the pressure of the sound must be adequately high.
A chemical reaction occurs when a solution is formed. True or false
Your answer would be False
Answer: It would be false. thank me later.
Mg is a member of which family?a) noble gases b) halogensc) alkaline earth metals d) alkali metalse)none of the above
Answer: Alkaline earth metals, as this is shown by its location on the periodic table
Mg is a member of the c) alkaline earth metals family.
Which is the alkaline earth metal?Group 2A (or IIA) of the Periodic Table is an alkaline earth metal. Beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra). They are harder and less reactive than Group 1A alkali metals.
Alkaline earth metals are named after the alkaline earths called beryllium, magnesia, limestone, strontium, and barite after their oxides. When mixed with water, these oxides are simple (alkaline).
The main difference between alkali metals and alkaline earth metals is that all alkali metals have one electron in the outermost shell, whereas all alkaline earth metals have two external electrons. That is.
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Which equation results from adding the equations in this system? -2x+y=8 5x-y=-5
Answer:
3 x = 3.
Value of x = 1 and y = 10.
Explanation:
Adding the two equations:-2x + y = 8
5x - y = -5
Will give:5x + (-2x) + y + (-y) = 8 + (-5)
∴ 3 x = 3.
∴ x = 1.
Substituting in any equation to get y:-2(1) + y = 8.
∴ y = 10.
Answer:
3x = 3
Explanation:
Got it right on edge 2020 :)
Use the free energies of formation given below to calculate the equilibrium constant (K) for the following reaction at 298 K. 2 HNO3(aq) + NO(g) → 3 NO2(g) + H2O(l) K = ? ΔG°f (kJ/mol) -110.9 87.6 51.3 -237.1 Use the free energies of formation given below to calculate the equilibrium constant (K) for the following reaction at 298 K. 2 HNO3(aq) + NO(g) → 3 NO2(g) + H2O(l) K = ? ΔG°f (kJ/mol) -110.9 87.6 51.3 -237.1 0.980 1.02 1.15 × 10-9 5.11 × 10-4 8.71 × 108
Answer:
K = 1.15 x 10⁻⁹.
Explanation:
We have the relation:ΔG°rxn = - RTlnK.
where, ΔG°rxn is the standard free energy change of the reaction.
R is the general gas constant (R = 8.314 J/mol.K).
T is the temperature of the reaction (K) (T = 298.0 K).
K is the equilibrium constant.
We can get ΔG°rxn using the relation:ΔG°rxn = ΣG°f, products – ΣG°f, reactants
ΔG°rxn = [3(G°f, NO₂) + (G°f, H₂O)] - [2(G°f, HNO₃) + (G°f, NO)]
ΔG°rxn = [3(51.3 kJ/mol) + (- 237.1 kJ/mol)] - [2(- 110.9 kJ/mol) + (87.6 kJ/mol)
ΔG°rxn = (- 83.2 kJ/mol) - (- 134.2 kJ/mol) = 51.0 kJ/mol.
∵ ΔG°rxn = - RTlnK.
∴ lnK = - (ΔG°rxn)/(RT) = - (51000 J/mol)/(8.314 J/mol.K)(298.0 K) = - 20.58.
∴ K = 1.15 x 10⁻⁹.
The equilibrium constant, K, for a particular reaction can be derived from the standard free-energy changes of reactions. First, calculate ΔG° by adding the ΔG°f values of the products, subtracting those of the reactants, then use the equation ΔG° = -RT lnK to solve for K.
Explanation:This problem is a matter of utilizing the formula to calculate the equilibrium constant (K) from the standard free-energy changes of reactions (ΔG°f). For this particular reaction 2 HNO3(aq) + NO(g) → 3 NO2(g) + H2O(l), we need to express ΔG° for the reaction in terms of the ΔG°f values given, using the formula:
ΔG° = Σ n ΔG°f (products) - Σ m ΔG°f (reactants)
Where, n and m are the stoichiometric coefficients. After calculating ΔG°, we can derive the equilibrium constant, K, using the equation:
ΔG° = -RT lnK
Where, R is the universal gas constant (8.314 J/mol.K), T is the temperature in Kelvin and K is the equilibrium constant. Solving for K gives the equilibrium constant for the reaction at 298 K.
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In full detail, explain what happens during the electrolysis of a NaCl brine? Be sure to identify what is being oxidized and what is being reduced (2). Identify where in the cell the reactions are taking place (2).
Answer:
Explanation:
Electrolysis of aqeous sodium chloride(NaCl)
Electrolysis is a process that converts electrical energy into chemical energy.
Electrolytic processes involves three major steps:
1. Ionization of electrolyte and water
2. Migration of ions to electrodes
3. Discharge of ions at the electrodes.
For the Electrolysis of brine, we follow these three steps:
1. Ionization of the aqeous brine solution:
NaCl → Na⁺ + Cl⁻
H₂O ⇄H⁺ + OH⁻
2. Migration of ions to the electrodes
The positive charges Na⁺ and H⁺ would both go to the cathode which is the negatively charged electrode
The negative charges Cl⁻ and OH⁻ migrates to the anode which are the positively charged electrodes. The anode is positively charged electrode.
3. Discharge of ions at the electrodes.
The preferential discharge of ions is based on the activity series and concentration of the ions.
On the activity series H is lower and it discharges preferentially to Na in the cathode:
2H⁺ + 2e⁻ → H₂
At this electrode, the cathode, reduction occurs and H⁺ ions are reduced.
At the anode Cl⁻ and OH⁻ migrates. But Cl⁻ is discharged preferentially due to its higher concentration.
2Cl⁻ ⇄ Cl₂ + 2e⁻
This is the oxidation half and Cl is oxidized