Problem 1
What factors affect the rate of a reaction?
Problem 2
How does a decrease in temperature affect the reaction rate? Explain the outcome by describing changes that occur at the molecular level.
Problem 3
For which of the following two reactions would you expect the orientation of the molecules to be more important? a) \(\mathrm{AB}+\mathrm{C} \rightarrow \mathrm{AC}+\mathrm{B}\) b) \(D+E \rightarrow F\)
Problem 4
Determine the relative rates of disappearance of reactants and formation of products for the following reactions: a) \(\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{NH}_{3}(\mathrm{~g})\) b) \(2 \mathrm{~A}+3 \mathrm{~B} \rightarrow 4 \mathrm{C}\) c) \(2 \mathrm{~N}_{2} \mathrm{O}_{5} \rightarrow 4 \mathrm{NO}_{2}+\mathrm{O}_{2}\)
Problem 6
For the following reaction: \(3 \mathrm{E}+2 \mathrm{~F} \rightarrow 2 \mathrm{G}\), the rate law is: Rate \(=k[\mathrm{~F}]^{2}\) a) How does the rate change if [E] is doubled? b) How does the rate change is [F] is doubled? c) What is the overall reaction order? d) What are the units for the rate constant for this reaction?
Problem 7
The rate of oxidation of bromide ions by bromate in an acidic aqueous solution is $$ 6 \mathrm{H}^{+}+\mathrm{BrO}_{3}^{-}+5 \mathrm{Br}^{-} \rightarrow 3 \mathrm{Br}_{2}+3 \mathrm{H}_{2} \mathrm{O} $$ and is found to follow the rate law $$ \text { Rate }=k\left[\mathrm{Br}^{-}\right]\left[\mathrm{BrO}_{3}^{-}\right]\left[\mathrm{H}^{+}\right]^{2} $$ What happens to the rate if, in separate experiments: a) \(\left[\mathrm{BrO}_{3}\right]\) is doubled? b) the \(\mathrm{pH}\) is increased by one unit? c) the solution is diluted to twice its volume, with the pH kept constant by use of a buffer?
Problem 10
What should be plotted on the \(x\) - and \(y\) -axis to obtain a straight line for: a) a first-order reaction? b) a zero-order reaction?
Problem 13
The half-life of a first-order reaction was found to be 10 min at a certain temperature. What is its rate constant in reciprocal seconds?
Problem 14
The mass- 241 isotope of americium, widely used as an ionizing source in smoke detectors, has a halflife of 432 years. a) What fraction of the \(\mathrm{Am}^{241}\) in a smoke detector will have decayed after 50 years? b) How long will it take for the activity to decline to \(80 \%\) of its initial value? c) What would be the "seventh-life" of \(\mathrm{Am}^{241}\) ? \(^{4}\)
Problem 17
State the molecularity and rate law for each of the following elementary steps: a) \(\mathrm{Cl}(\mathrm{g})+\mathrm{CCl}_{3}(\mathrm{~g}) \rightarrow \mathrm{CCl}_{4}(\ell)\) b) \(\mathrm{Br}_{2} \rightarrow 2 \mathrm{Br}\) c) \(2 \mathrm{~A} \rightarrow \mathrm{B}\)
