Rate of Reaction

Q. For an elementary chemical reaction,
the expression for $\frac{d\left[A\right]}{dt}$ is

1. $2k_1\left[A_2\right]-2k_{-1}[A{]}^2$
2. $k_1\left[A_2\right]-k_{-1}[A{]}^2$
3. $k_1\left[A_2\right]+k_{-1}[A{]}^2$
4. $2k_1\left[A_2\right]-k_{-1}[A{]}^2$

Q. For the reaction 2A + B + C $\to A_{2}B$ + C the rate law is found to be Rate =k[A][B]${}^2$ with $k=2\times {10}^{-6}mo{l}^{-2}{L}^2{s}^{-1}$
The initial rate of reaction with $\left[A\right]=0.1mol{L}^{-1},\left[B\right]=0.2mol{L}^{-1}and\left[C\right]=0.8mol{L}^{-1}$ is

1. $8\times {10}^{-9}mol{L}^{-1}{s}^{-1}$
2. $6.4\times {10}^{-8}mol{L}^{-1}{s}^{-1}$
3. $4\times {10}^{-7}mol{L}^{-1}{s}^{-1}$
4. $4\times {10}^{-3}mol{L}^{-1}{s}^{-1}$

Q. Nitrogen tetra oxide $\left(N_2{O}_4\right)$ decomposes as $N_2{O}_4\left(g\right)\to 2N{O}_2\left(g\right)$. If the pressure of $\left(N_2{O}_4\right)$ falls from 0.50 atm to 0.32 atm is 30 minutes, the rate of appearance of $N{O}_2\left(g\right)$ is

1. 0.006 atm/min
2. 0.003 atm/min
3. 0.012 atm/min
4. 0.024 atm/min

Q. The concentration of a reactant changes from .03M to .02M in 25 minutes. The average rate of reaction, using time in seconds is

1. $6.67\times {10}^{-6}mol/l/s$
2. $0.4\times {10}^{-3}mol/l/s$
3. $0.024mol/l/s$
4. $0.24mol/l/s$

Q. The data for the reaction is A + B $\to$C is
$\begin{array}{cccc}Exp.& [A{]}_0& [B{]}_0& Initialrate\\ 1& 0.012& 0.035& 0.10\\ 2& 0.024& 0.035& 0.80\\ 3& 0.012& 0.070& 0.10\\ 4& 0.024& 0.070& 0.80\end{array}$

1. $r=k[B{]}^3$
2. $r=k[A{]}^3$
3. $r=k\left[A\right][B{]}^4$
4. $r=k\left[A{]}^2\right[B{]}^2$

Q. The rate of a reaction is expressed in different ways as follows:
$\frac{1}{2}\left(\frac{d\left[C\right]}{dt}\right)=-\frac{1}{3}\left(\frac{d\left[D\right]}{dt}\right)=\frac{1}{4}\left(\frac{d\left[A\right]}{dt}\right)=-\left(\frac{d\left[B\right]}{dt}\right)$
The reaction is

1. $4A+2B\to 2C+3D$
2. $B+\left(1/2\right)D\to 4A+3C$
3. $4A+B\to 2C+3D$
4. $B+3D\to 4A+2C$

Q. A reaction follows the given concentration (M)-time graph. The rate for this reaction at 20 seconds will be

1. $4\times {10}^{-3}M/s$
2. $8\times {10}^{-2}M/s$
3. $2\times {10}^{-2}M/s$
4. $7\times {10}^{-3}M/s$

Q. $xA+yB\to zC.If-\frac{d\left[A\right]}{dt}=-\frac{d\left[B\right]}{dt}=1.5\frac{d\left[C\right]}{dt}$ then x.y and z are

1. 1, 1, 1
2. 3, 2, 3
3. 3, 3, 2
4. 2, 2, 3

Q. In the following reaction, how is the rate of appearance of product related to the rate of disappearance of the reactant?
$Br{O}_3^{-}\left(aq\right)+5B{r}^{-1}\left(aq\right)+6H^{+}\to 3B{r}_2\left(l\right)+2H_{2}O\left(l\right)$

1. $\frac{d\left[B{r}_2\right]}{dt}=-\frac{d\left[B{r}^{-}\right]}{dt}$
2. $\frac{d\left[B{r}_2\right]}{dt}=\frac{3}{5}\frac{d\left[B{r}^{-}\right]}{dt}$
3. $\frac{d\left[B{r}_2\right]}{dt}=-\frac{3}{5}\frac{d\left[B{r}^{-}\right]}{dt}$
4. $\frac{d\left[B{r}_2\right]}{dt}=-\frac{5}{3}\frac{d\left[B{r}^{-}\right]}{dt}$

Q. The rate at which a substance reacts depends upon:

1. Atomic weight
2. Atomic number
3. Molecular weight
4. Active mass