Q: Given the following mechanism: Step 1: $$\mathrm{NO_2$} + \mathrm{F_2$} \rightarrow \mathrm{NO_2F} + \mathrm{F} ($$slow) Step 2: $$\mathrm{F} + \mathrm{NO_2$} \rightarrow \mathrm{NO_2F} ($$fast) What is the rate law for the overall reaction?

$$\text{rate} = k[\mathrm{NO_2$}][\mathrm{F_2$}]$$

Question 1

Which of the following best describes a supersaturated solution?

Accepted Answer

A solution that contains more dissolved solute than is present in a saturated solution at the same temperature.

Question 2

Which of the following intermolecular forces is primarily responsible for the high solubility of ethanol ($$\mathrm{C_2H_5OH}) in $$water?

Accepted Answer

Hydrogen bonding

Question 3

A 0.10 mol sample of $$\mathrm{Na_2SO_4} is $$dissolved in enough water to make 1.0 L of solution. How many moles of particles are present in the solution, assuming complete dissociation?

Accepted Answer

$$0.30$$ mol

Question 4

Which of the following changes will increase the solubility of a gas in a liquid solvent?

Accepted Answer

Decreasing the temperature and increasing the pressure above the solution

Question 5

A solution is prepared by dissolving 10.0 g of glucose ($$\mathrm{C_6H_{12}O_6$}$$, molar mass = $$180.0\ \mathrm{g/mol}) in 90.0 g of $$water. What is the molality of the solution?

Accepted Answer

$$0.617\ \mathrm{mol/kg}$$

Question 6

Which of the following best describes a colligative property?

Accepted Answer

A property that depends only on the number of solute particles in solution, not their identity.

Question 7

A solution is made by dissolving a nonvolatile solute in water. According to Raoult’s Law, what happens to the vapor pressure of the solution compared to pure water?

Accepted Answer

The vapor pressure decreases.

Question 8

The rate law for a reaction is $$	ext{rate} = k[\mathrm{A}]^2[\mathrm{B}]. $$What is the overall order of the reaction?

Accepted Answer

3

Question 9

Which of the following statements about the rate constant $$k is $$correct?

Accepted Answer

The value of $$k$$ increases as temperature increases.

Question 10

For a first-order reaction, which of the following equations correctly relates the concentration of reactant $$[A] at $$time $$t to $$its initial concentration $$[A]_0$$ and the rate constant $$k$$?

Accepted Answer

$$\ln\left(\frac{[A]}{[A]_0}\right) = -kt$$

Question 11

A reaction has an activation energy of $$50\ \mathrm{kJ/mol}. $$According to the Arrhenius equation, what will happen to the rate constant if the temperature is increased?

Accepted Answer

The rate constant will increase.

Question 12

Which of the following is true about a catalyst in a chemical reaction?

Accepted Answer

It lowers the activation energy and increases the reaction rate without being consumed.

Question 13

Given the following mechanism:

Step 1: $$\mathrm{NO_2$} + \mathrm{F_2$} \rightarrow \mathrm{NO_2F} + \mathrm{F} ($$slow)
Step 2: $$\mathrm{F} + \mathrm{NO_2$} \rightarrow \mathrm{NO_2F} ($$fast)

What is the rate law for the overall reaction?

Accepted Answer

$$	ext{rate} = k[\mathrm{NO_2$}][\mathrm{F_2$}]$$

Question 14

A reaction is found to be second order with respect to $$\mathrm{A}$$ and zero order with respect to $$\mathrm{B}. If $$the concentration of $$\mathrm{A} is $$doubled and $$\mathrm{B} is $$tripled, how does the rate change?

Accepted Answer

The rate increases by a factor of 4.

Question 15

Which of the following best explains why increasing temperature generally increases the rate of a chemical reaction?

Accepted Answer

It increases the fraction of molecules with enough energy to overcome the activation energy barrier.

Question 16

A reaction has a half-life that is independent of the initial concentration of the reactant. What is the order of the reaction?

Accepted Answer

First order

Question 17

A student is asked to determine the order of a reaction with respect to $$\mathrm{A}$$ using concentration vs. time data. Which plot should yield a straight line if the reaction is first order in $$\mathrm{A}$$?

Accepted Answer

$$\ln [\mathrm{A}] vs. $$time

Question 18

A 1.0 L solution contains 0.10 mol of $$\mathrm{NaCl} (a $$strong electrolyte) and 0.10 mol of $$\mathrm{C_6H_{12}O_6$} (a $$nonelectrolyte). Which solution will have the higher boiling point elevation, assuming ideal behavior?

Accepted Answer

The $$\mathrm{NaCl}$$ solution

Question 19

A sample of oxygen gas is dissolved in water at 25°C. If the partial pressure of oxygen above the solution is doubled, what happens to the concentration of dissolved oxygen?

Accepted Answer

It doubles.

Chapter 14 & 15 Study Guide: Solutions and Chemical Kinetics

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