Chapter 9

\(\mathrm{N}_{2} \mathrm{O}_{5}\) decomposes according to equation; \(2 \mathrm{~N}_{2} \mathrm{O}_{5} \longrightarrow 4 \mathrm{NO}_{2}+\mathrm{O}_{2}\) (a) What does \(-\frac{d\left[\mathrm{~N}: \mathrm{C}_{5}\right]}{d t}\) denote? (b) What does \(\frac{d\left[\mathrm{O}_{2}\right]}{d t}\) denote? (c) What is the unit of rate of this reaction?

The reaction; \(2 \mathrm{NO}+\mathrm{Br}_{2} \longrightarrow 2 \mathrm{NOBr}\), is supposed to follow the following mechanism, (i) \(\mathrm{NO}+\mathrm{Br}_{2} \stackrel{\text { fast }}{\longrightarrow} \mathrm{NOBr}_{2}\) (ii) \(\mathrm{NOBr}_{2}+\mathrm{NO} \stackrel{\text { slow }}{\longrightarrow} 2 \mathrm{NOBr}\) Suggest the rate law expression.

Derive the relationship between rate of reaction, rate of disappearance of \(X, Y\) and rate of formation of \(X_{2} Y_{2}\) for the reaction : $$ 2 X+3 Y \longrightarrow X_{2} Y_{3} $$

For the reaction; \(4 \mathrm{NH}_{3(\mathrm{~g})}+5 \mathrm{O}_{2(\mathrm{~g})} \longrightarrow 4 \mathrm{NO}_{(\mathrm{g})}+6 \mathrm{H}_{2} \mathrm{O}_{(\mathrm{g})}\), the rate of reaction in terms of disappearance of \(\mathrm{NH}_{3}\) is \(-\frac{d\left[\mathrm{NH}_{3}\right]}{d t}\), then write the rate expression in terms of concentration of \(\mathrm{O}_{2}, \mathrm{NO}\) and \(\mathrm{H}_{2} \mathrm{O}\)

The reaction; \(2 \mathrm{~N}_{2} \mathrm{O}_{5} \longrightarrow 4 \mathrm{NO}_{2}+\mathrm{O}_{2}\), shows an increase in concentration of \(\mathrm{NO}_{2}\) by \(20 \times 10^{-3}\) mol litre \(^{-1}\) in 5 second. Calculate (a) rate of appearance of \(\mathrm{NO}_{2}\), (b) rate of reaction and (c) rate of disappearance of \(\mathrm{N}_{2} \mathrm{O}_{5}\).

For the decomposition reaction: \(\mathrm{N}_{2} \mathrm{O}_{4(\mathrm{~g})} \longrightarrow 2 \mathrm{NO}_{2(\mathrm{~g})} ;\) the initial pressure of \(\mathrm{N}_{2} \mathrm{O}_{4}\) falls from \(0.46\) atm to \(0.28\) atm in 30 minute. What is the rate of appearance of \(\mathrm{NO}_{2}\) ?

The rate of change in concentration of \(C\) in the reaction; \(2 A+B \longrightarrow 2 C+3 D\), was reported as \(1.0 \mathrm{~mol}\) litre \(^{-1} \mathrm{sec}^{-1} .\) Calculate the reaction rate as well as rate of change of concentration of \(A, B\), and \(D\).

A chemical reaction \(2 A \longrightarrow 4 B+C ;\) in gaseous phase shows an increase in concentration of \(B\) by \(5 \times 10^{-3} M\) in 10 second. Calculate: (a) rate of appearance of \(B\), (b) rate of the reaction, (c) rate of disappearance of \(A\).

From the rate expression for the following reactions, determine their order of renction and the dimensions of the rate constants. (u) \(\mathrm{WNO}_{(\mathrm{k})} \cdots \mathrm{N}_{2} \mathrm{O}_{(\mathrm{g})}+\mathrm{NO}_{2(\mathrm{~g})} ; \quad\) Rate \(=K[\mathrm{NO}]^{2}\) Rate \(=K\left[\mathrm{H}_{2} \mathrm{O}_{2}\right][\mathrm{I}]\) (c) \(\mathrm{CH}_{3} \mathrm{CHO}_{(\mathrm{g})} \longrightarrow \mathrm{CH}_{4(\mathrm{~g})}+\mathrm{CO}_{(\mathrm{g})} ;\) Rate \(=K\left[\mathrm{CH}_{3} \mathrm{CHO}\right]^{3 / 2}\) (d) \(\mathrm{CHCl}_{3(\mathrm{~g})}+\mathrm{Cl}_{2(g)} \longrightarrow \mathrm{CCl}_{4(\mathrm{~g})}+\mathrm{HCl}_{(\mathrm{g})}\) Rate \(=K\left[\mathrm{CHCl}_{3}\right]\left[\mathrm{Cl}_{2}\right]^{1 / 2}\)

The reaction; \(2 A+B+C \longrightarrow D+2 E ;\) is found to be I order in \(A\), II order in \(B\) and zero order in \(C\). (a) Write the rate expression. (b) What is the effect on rate on increasing the conc. of \(A, B\) and \(C\) two times?