College

3. The following data of the decomposition reaction of thionyl chloride \((\text{SO}_2\text{Cl}_2)\) were collected at a certain temperature, and the concentration of \(\text{SO}_2\text{Cl}_2\) was monitored as shown in the table:

\[
\text{SO}_2\text{Cl}_2 (g) \rightarrow \text{SO}_2 (g) + \text{Cl}_2 (g)
\]

| Time (min) | Conc. of \(\text{SO}_2\text{Cl}_2\) (mol/L) |
|------------|-------------------------------------------|
| 0 | 0.1000 |
| 100 | 0.0876 |
| 200 | 0.0768 |
| 300 | 0.0673 |
| 400 | 0.0590 |
| 500 | 0.0517 |
| 600 | 0.0453 |
| 700 | 0.0397 |
| 800 | 0.0348 |
| 900 | 0.0305 |
| 1000 | 0.0267 |
| 1100 | 0.0234 |

a) Determine graphically whether the kinetics of the reaction is zero order, first order, or second order with respect to \(\text{SO}_2\text{Cl}_2\), and then write the rate equation.

b) Determine the rate constant (\(k\)) of the reaction.

c) Determine the half-life (\(t_{1/2}\)) for the reaction.

d) What will be the concentration of \(\text{SO}_2\text{Cl}_2\) left in the reaction mixture at 1500 minutes?

Answer :

Answer:

a) First-order.

b) 0.013 min⁻¹

c) 53.3 min.

d) 0.0142M

Explanation:

Hello,

In this case, on the attached document, we can notice the corresponding plot for each possible order of reaction. Thus, we should remember that in zeroth-order we plot the concentration of the reactant (SO2Cl2 ) versus the time, in first-order the natural logarithm of the concentration of the reactant (SO2Cl2 ) versus the time and in second-order reactions the inverse of the concentration of the reactant (SO2Cl2 ) versus the time.

a) In such a way, we realize the best fit is exhibited by the first-order model which shows a straight line (R=1) which has a slope of -0.0013 and an intercept of -2.3025 (natural logarithm of 0.1 which corresponds to the initial concentration). Therefore, the reaction has a first-order kinetics.

b) Since the slope is -0.0013 (take two random values), the rate constant is 0.013 min⁻¹:

[tex]m=\frac{ln(0.0768)-ln(0.0876)}{200min-100min} =-0.0013min^{-1}[/tex]

c) Half life for first-order kinetics is computed by:

[tex]t_{1/2}=\frac{ln(2)}{k}=\frac{ln(2)}{0.013min^{-1}} =53.3min[/tex]

d) Here, we compute the concentration via the integrated rate law once 1500 minutes have passed:

[tex]C=C_0exp(-kt)=0.1Mexp(-0.013min^{-1}*1500min)\\\\C=0.0142M[/tex]

Best regards.