A `to` products. The concentration of A changes from 0.2 to 0.15 mol `L^(-1)` in 10 min. Calculate the average rate.

Answer

To calculate the average rate of the reaction where the concentration of reactant A changes from 0.2 mol/L to 0.15 mol/L in 10 minutes, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Initial and Final Concentrations**:
- Initial concentration of A, \( [A_0] = 0.20 \, \text{mol/L} \)
- Final concentration of A, \( [A] = 0.15 \, \text{mol/L} \)

2. **Determine the Change in Concentration**:
- Change in concentration, \( \Delta [A] = [A_0] - [A] = 0.20 \, \text{mol/L} - 0.15 \, \text{mol/L} = 0.05 \, \text{mol/L} \)

3. **Identify the Time Interval**:
- Time interval, \( \Delta t = 10 \, \text{minutes} \)

4. **Calculate the Average Rate of Reaction**:
- The average rate of reaction is given by the formula:
\[ \text{Average Rate} = -\frac{\Delta [A]}{\Delta t} \]
- Substituting the values:
\[ \text{Average Rate} = -\frac{0.05 \, \text{mol/L}}{10 \, \text{min}} = -0.005 \, \text{mol/L/min} \]

5. **Express the Rate with Correct Sign**:
- Since the concentration of A is decreasing, we take the negative sign into account:
\[ \text{Average Rate} = 5 \times 10^{-3} \, \text{mol/L/min} \]

### Final Answer:
The average rate of the reaction is \( 5 \times 10^{-3} \, \text{mol/L/min} \).

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