Q: Consult the Arrhenius plot below. The equation of the best fit line is $$y = -2766.4x + 25.105. $$What is the activation energy $$E_a in J/$$mol?

$$2.77 \times 10^3$ \text{ kJ/mol}

Question 1

For a reaction, the rate triples when the concentration of BrO$$_3^-$$ triples, while the rate is unaffected by doubling the concentration of H$$^+. $$What is the order of the reaction with respect to BrO$$_3^-$$ and H$$^+$$, respectively?

Accepted Answer

Order with respect to BrO$$_3^-$$: 1; Order with respect to H$$^+$$: 0

Question 2

Which variable is typically held constant when determining reaction rates as a function of different starting concentrations?

Accepted Answer

Temperature

Question 3

Given the half-life of $$^{14}C is 5700 $$years and the error of measurement is 0.5%, what is the maximum age of a sample that can be measured by $$^{14}C $$dating?

Accepted Answer

$$143560$$ years

Question 4

For the consecutive reaction $$A \rightarrow B \rightarrow C$$, with first-order rate constants $$k_1$$ and $$k_2$$, which of the following best describes the graph of $$[A]$$ versus time?

Accepted Answer

Exponentially decreases

Question 5

For the reaction $$A \rightarrow B \rightarrow C$$, what is the rate of change of the intermediate $$[B]$$?

Accepted Answer

$$\frac{d[B]}{dt} = k_1$[A] - k_2$[B]$$

Question 6

Consult the Arrhenius plot below. The equation of the best fit line is $$y = -2766.4x + 25.105. $$What is the activation energy $$E_a in J/$$mol?

Accepted Answer

$$2.77 	imes 10^3$ 	ext{ kJ/mol}

Question 7

The Arrhenius parameter $$A$$ would be a small number if:

Accepted Answer

The reaction has large steric requirements

Question 8

The Arrhenius parameters for the gas phase decomposition of cyclobutane $$C_4H_8(g) ightarrow 2C_2H_4(g)$$ are $$A = 4.00 	imes 10$$^{15}$$ 	ext{ s}^{-1}$$ and $$E_a = 261 	ext{ kJ mol}^{-1}. $$What is the half-life of cyclobutane at $$T = 488 K$$?

Accepted Answer

$$141.5$$ 	ext{ s}

Question 9

If $$K ($$equilibrium constant) is known from experiment, which thermodynamic quantity can be computed?

Accepted Answer

$$\Delta G^\circ$$

Question 10

If $$\Delta G^\circ is $$known from experiment, which of the following can be computed?

Accepted Answer

$$K$$

Question 11

Consider two reactions, both exhibiting Arrhenius behavior:
Reaction 1: $$E_a = 25.5 kJ/$$mol and $$\Delta S^\circ = -58.0 J/$$mol K
Reaction 2: $$E_a = 33.5 kJ/$$mol and $$\Delta S^\circ = -67.7 J/$$mol K
What can be said about the rate of reaction 1 ($$k_1) $$compared to reaction 2 ($$k_2$$)?

Accepted Answer

$$k_1$$ \u003c $$k_2$$

Question 12

Which of the following statements about the Arrhenius equation is correct?

Accepted Answer

The rate constant $$k$$ increases as temperature increases

Question 13

A student is investigating the effect of temperature on the rate of a reaction. Which experimental variable should be held constant to ensure valid results?

Accepted Answer

Concentration of reactants

Question 14

Which of the following best explains why the pre-exponential factor $$A in $$the Arrhenius equation can be small for some reactions?

Accepted Answer

The reactants have difficulty colliding in the correct orientation

Question 15

In a consecutive reaction $$A \rightarrow B \rightarrow C$$, if $$k_2$$ \gg $$k_1$$, what happens to the concentration of intermediate $$B$$ over time?

Accepted Answer

$$[B]$$ quickly reaches a low steady-state value

Question 16

Which of the following is a correct expression for the rate constant $$k$$ from an Arrhenius plot of $$\ln k$$ versus $$1/T$$?

Accepted Answer

$$k = Ae$$^{-E_a/RT}$$

Question 17

A reaction is found to be zero order with respect to reactant $$X. $$What will happen to the rate if the concentration of $$X is $$doubled?

Accepted Answer

The rate will remain unchanged

Question 18

Which of the following is NOT a valid reason for a reaction to have a high activation energy?

Accepted Answer

The reactants are already at equilibrium

Question 19

Which of the following would increase the rate constant $$k$$ for a reaction according to the Arrhenius equation?

Accepted Answer

Decreasing the activation energy $$E_a$$

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