Q: For the reaction $$2H_2O_2 (aq) \rightarrow 2H_2O (l) + O_2$ (g)$$, if $$[H_2O_2]$$ decreases by $$0.010\ \mathrm{M} in 1200 $$seconds, what is the average rate of disappearance of $$H_2O_2 in$$ $$\mathrm{M}/\mathrm{s}$$?

$$-8.33 \times 10$$^{-6}$$\ \mathrm{M}/\mathrm{s}$$

Q: In the reaction $$A + 3B \rightarrow 2C + 2D$$, which mathematical relationship is correct for the overall rate?

$$\text{Rate} = -\dfrac{d[A]}{dt} = -\dfrac{1}{3} \dfrac{d[B]}{dt} = \dfrac{1}{2} \dfrac{d[C]}{dt} = \dfrac{1}{2} \dfrac{d[D]}{dt}$$

Question 1

Which of the following factors will NOT generally increase the rate of a chemical reaction?

Accepted Answer

Decreasing the temperature

Question 2

For the reaction $$4\mathrm{NH}_3 (g) + 5\mathrm{O}_2 (g) \rightarrow 4\mathrm{NO} (g) + 6\mathrm{H}_2\mathrm{O} (g)$$, which expression correctly relates the rate of disappearance of $$\mathrm{NH}_3 to $$the rate of appearance of $$\mathrm{H}_2\mathrm{O}$$?

Accepted Answer

$$\dfrac{d[\mathrm{NH}_3]}{dt} = \dfrac{1}{1.5} \dfrac{d[\mathrm{H}_2\mathrm{O}]}{dt}$$

Question 3

A student measures the concentration of reactant A in the reaction $$A + 3B \rightarrow 2C + 2D$$ and finds $$[A]$$ decreases from $$1.000\ \mathrm{M} to$$ $$0.900\ \mathrm{M} in 100 $$minutes. What is the average rate of disappearance of A in $$\mathrm{M}/\mathrm{min}$$?

Accepted Answer

$$-0.0010\ \mathrm{M}/\mathrm{min}$$

Question 4

In the decomposition of hydrogen peroxide $$2\mathrm{H}_2\mathrm{O}_2 (aq) \rightarrow 2\mathrm{H}_2\mathrm{O} (l) + \mathrm{O}_2 (g)$$, which graph best represents the change in concentration of $$\mathrm{O}_2$$ over time?

Accepted Answer

A curve that increases and then levels off

Question 5

Which of the following is the correct general form of a rate law for a reaction $$aA + bB \rightarrow$$ products?

Accepted Answer

$$	ext{Rate} = k[A]^m[B]^n$$

Question 6

If doubling the concentration of reactant A causes the rate of reaction to quadruple, what is the order of the reaction with respect to A?

Accepted Answer

Second order

Question 7

Which statement best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

It lowers the activation energy, increasing the reaction rate

Question 8

For the reaction $$A + 3B \rightarrow 2C + 2D$$, if the rate of disappearance of A is $$-0.100\ \mathrm{M}/\mathrm{min}$$, what is the rate of appearance of C?

Accepted Answer

$$0.200\ \mathrm{M}/\mathrm{min}$$

Question 9

Which of the following methods is commonly used to experimentally determine the rate law of a reaction?

Accepted Answer

Method of Initial Rates

Question 10

In a reaction, the rate law is found to be $$	ext{Rate} = k[NO]^2[O_2$]. If $$the concentration of $$NO is $$doubled and $$O_2 is $$kept constant, by what factor does the rate increase?

Accepted Answer

4

Question 11

Which of the following best describes an instantaneous rate of reaction?

Accepted Answer

The rate at a specific moment, determined by the slope of the tangent to the concentration vs. time curve

Question 12

For the reaction $$2H_2O_2 (aq) \rightarrow 2H_2O (l) + O_2$ (g)$$, if $$[H_2O_2]$$ decreases by $$0.010\ \mathrm{M} in 1200 $$seconds, what is the average rate of disappearance of $$H_2O_2 in$$ $$\mathrm{M}/\mathrm{s}$$?

Accepted Answer

$$-8.33 	imes 10$$^{-6}$$\ \mathrm{M}/\mathrm{s}$$

Question 13

Which of the following is NOT a factor that affects the rate of a chemical reaction?

Accepted Answer

Color of the reactants

Question 14

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 15

In the reaction $$A + 3B \rightarrow 2C + 2D$$, which mathematical relationship is correct for the overall rate?

Accepted Answer

$$	ext{Rate} = -\dfrac{d[A]}{dt} = -\dfrac{1}{3} \dfrac{d[B]}{dt} = \dfrac{1}{2} \dfrac{d[C]}{dt} = \dfrac{1}{2} \dfrac{d[D]}{dt}$$

Question 16

Which scenario would most likely result in a faster reaction rate?

Accepted Answer

Increasing the pressure for a reaction involving gases

Question 17

Why does the rate of a chemical reaction typically decrease as the reaction proceeds?

Accepted Answer

The concentration of reactants decreases

Question 18

In the method of initial rates, what is the primary variable that is changed to determine the order of a reaction?

Accepted Answer

Concentration of reactants

Question 19

Which of the following best explains why the average rate and instantaneous rate of a reaction may not match?

Accepted Answer

The rate changes as the concentration of reactants changes over time

Chemical Kinetics: Reaction Rates and Rate Laws

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