Q: A scuba diver descends to a depth where the partial pressure of oxygen is 2.5 atm. According to Henry's Law, if the Henry's Law constant for oxygen in blood at body temperature is $$k_H = 1.3 \times 10$$^{-3}$$ \ \mathrm{mol/(L \cdot atm)}$$, what is the concentration of dissolved oxygen in the diver's blood at this depth?

$$3.25 \times 10$$^{-3}$$ \ \mathrm{mol/L}$$

Question 1

A scuba diver descends to a depth where the partial pressure of oxygen is 2.5 atm. According to Henry's Law, if the Henry's Law constant for oxygen in blood at body temperature is $$k_H = 1.3 	imes 10$$^{-3}$$ \ \mathrm{mol/(L \cdot atm)}$$, what is the concentration of dissolved oxygen in the diver's blood at this depth?

Accepted Answer

$$3.25 	imes 10$$^{-3}$$ \ \mathrm{mol/L}$$

Question 2

A solution is prepared by dissolving a nonvolatile solute in water, causing the boiling point to rise. If the boiling point elevation constant $$K_b$$ for water is $$0.512 \ ^\circ \mathrm{C} \cdot \mathrm{kg/mol}$$ and the molality of the solution is $$2.0 \ \mathrm{mol/kg}$$, what is the boiling point elevation?

Accepted Answer

$$1.02 \ ^\circ \mathrm{C}$$

Question 3

A reaction follows first-order kinetics. If the initial concentration of the reactant is $$0.80 \ \mathrm{mol/L}$$ and after 30 minutes it drops to $$0.20 \ \mathrm{mol/L}$$, what is the rate constant $$k$$ for the reaction?

Accepted Answer

$$0.046 \ \mathrm{min}^{-1}$$

Question 4

Which of the following best describes the effect of adding a nonvolatile solute to a solvent on its freezing point?

Accepted Answer

The freezing point decreases because the solute lowers the vapor pressure.

Question 5

A solution contains $$0.5 \ \mathrm{mol} of $$glucose in $$1.0 \ \mathrm{L} of $$water at $$25^\circ \mathrm{C}. $$What is the osmotic pressure of the solution? ($$R = 0.0821 \ \mathrm{L \cdot atm/(mol \cdot K)})$$

Accepted Answer

$$1.22 \ \mathrm{atm}$$

Question 6

For a second-order reaction with respect to $$A$$, if $$[A]_0 = 0.10 \ \mathrm{mol/L}$$ and $$k = 0.20 \ \mathrm{L/(mol \cdot s)}$$, what is the half-life of the reaction?

Accepted Answer

$$5.0 \ \mathrm{s}$$

Question 7

A gas is collected over water at $$25^\circ \mathrm{C}$$ and the total pressure is $$760 \ \mathrm{mmHg}. If $$the vapor pressure of water at this temperature is $$24 \ \mathrm{mmHg}$$, what is the partial pressure of the collected gas?

Accepted Answer

$$736 \ \mathrm{mmHg}$$

Question 8

Which equation would you use to determine the rate constant $$k$$ for a reaction if you know the activation energy $$E_a$$, the frequency factor $$A$$, and the temperature $$T$$?

Accepted Answer

$$k = A e$$^{-E_a/(RT)}$$

Question 9

A zero-order reaction has a rate constant $$k = 0.10 \ \mathrm{mol/(L \cdot s)}$$ and an initial concentration $$[A]_0 = 0.50 \ \mathrm{mol/L}. $$How long will it take for the concentration to decrease to $$0.10 \ \mathrm{mol/L}$$?

Accepted Answer

$$4.0 \ \mathrm{s}$$

Question 10

If the rate constant $$k$$ for a reaction doubles when the temperature increases from $$300 \ \mathrm{K} to$$ $$310 \ \mathrm{K}$$, what can you infer about the activation energy $$E_a$$?

Accepted Answer

The activation energy is low, as a small temperature increase causes a large increase in $$k.$$

Question 11

A solution of sodium chloride is prepared and its vapor pressure is measured. Which law best describes the relationship between the vapor pressure of the solution and the mole fraction of the solvent?

Accepted Answer

Raoult's Law

Question 12

Which of the following statements about osmotic pressure is correct?

Accepted Answer

Osmotic pressure increases with increasing solute concentration.

Question 13

A reaction has a half-life that does not depend on the initial concentration of the reactant. What is the order of the reaction?

Accepted Answer

First order

Question 14

A chemist wants to lower the freezing point of a solution as much as possible. Which of the following changes will have the greatest effect?

Accepted Answer

Increase the amount of nonvolatile solute added.

Question 15

If the rate law for a reaction is $$	ext{rate} = k[A][B]^2$$, what is the overall order of the reaction?

Accepted Answer

Third order

Question 16

A reaction has an activation energy of $$50 \ \mathrm{kJ/mol}. If $$the temperature is increased, what happens to the rate constant $$k$$?

Accepted Answer

The rate constant increases.

Question 17

Which of the following best explains why salt is spread on icy roads in winter?

Accepted Answer

Salt decreases the freezing point of water, causing ice to melt.

Question 18

A first-order reaction has a rate constant $$k = 0.693 \ \mathrm{min}^{-1}. $$What is the half-life of the reaction?

Accepted Answer

$$1.0 \ \mathrm{min}$$

Question 19

Which of the following is the correct integrated rate law for a zero-order reaction?

Accepted Answer

$$[A] = [A]_0 - kt$$

Solution & Colligative Property Equations and Reaction Kinetics

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