Book cover for Chemistry and Chemical Reactivity

Chemistry and Chemical Reactivity

John C. Kotz, Paul M. Treichel, John R. Townsend

ISBN #9780495387039

7th Edition

2,044 Questions

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Summary
Learning Objectives
Key Concepts
Example Problems
Explanations
Common Mistakes

Summary

This section covers the fundamentals of chemical kinetics, outlining how reaction rates are measured and influenced by various factors, including reactant concentration, temperature, and the presence of catalysts. Key topics include rate laws, reaction order, integrated rate equations, half-life concepts, and the role of collision theory and activation energy. Understanding these concepts allows chemists to predict reaction behavior, deduce reaction mechanisms, and control industrial processes through catalysts.

Learning Objectives

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Key Concepts

CONCEPT

DEFINITION

Definition: A branch of chemistry focused on substances that donate (acids) or accept (bases) protons (or electron pairs in the Lewis definition) during reactions.

A branch of chemistry focused on substances that donate (acids) or accept (bases) protons (or electron pairs in the Lewis definition) during reactions. •

Example Problems

Example 1

Give the relative rates of disappearance of reactants and formation of products for each of the following reactions. (a) $2 \mathrm{O}_{3}(\mathrm{g}) \longrightarrow 3 \mathrm{O}_{2}(\mathrm{g})$ (b) $2 \mathrm{HOF}(\mathrm{g}) \longrightarrow 2 \mathrm{HF}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g})$

Example 2

Give the relative rates of disappearance of reactants and formation of products for each of the following reactions. (a) $2 \mathrm{NO}(\mathrm{g})+\mathrm{Br}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{NOBr}(\mathrm{g})$ (b) $\mathrm{N}_{2}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{g}) \longrightarrow 2 \mathrm{NH}_{3}(\mathrm{g})$

Example 3

In the reaction $2 \mathrm{O}_{3}(\mathrm{g}) \longrightarrow 3 \mathrm{O}_{2}(\mathrm{g}),$ the rate of formation of $\mathrm{O}_{2}$ is $1.5 \times 10^{-3} \mathrm{mol} / \mathrm{L} \cdot$ s. What is the rate of decomposition of $\mathrm{O}_{3} ?$

Example 4

In the synthesis of ammonia, if $-\Delta\left[\mathrm{H}_{2}\right] / \Delta t=$ $4.5 \times 10^{-4} \mathrm{mol} / \mathrm{L} \cdot \mathrm{min},$ what is $\Delta\left[\mathrm{NH}_{3}\right] / \Delta t ?$ $$\mathrm{N}_{2}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{NH}_{3}(\mathrm{g})$$

Example 5

Experimental data are listed here for the reaction $A \longrightarrow 2 B$ $$\begin{array}{lc} \begin{array}{l} \text { Time } \\ (\mathrm{s}) \end{array} & \begin{array}{l} {[\mathrm{B}]} \\ (\mathrm{mo} / / \mathrm{L}) \end{array} \\ \hline 0.00 & 0.000 \\ 10.0 & 0.326 \\ 20.0 & 0.572 \\ 30.0 & 0.750 \\ 40.0 & 0.890 \\ \hline \end{array}$$ (a) Prepare a graph from these data; connect the points with a smooth line; and calculate the rate of change of [B] for each $10-$ s interval from 0.0 to $40.0 \mathrm{s} .$ Does the rate of change decrease from one time interval to the next? Suggest a reason for this result. (b) How is the rate of change of $[\mathrm{A}]$ related to the rate of change of $[\mathrm{B}]$ in each time interval? Calculate the rate of change of $[\mathrm{A}]$ for the time interval from 10.0 to $20.0 \mathrm{s}.$ (c) What is the instantaneous rate, $\Delta[\mathrm{B}] / \Delta \mathrm{t},$ when $[\mathrm{B}]=0.750 \mathrm{mol} / \mathrm{L} ?$
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Common Mistakes

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