The temperature coefficient of a reaction is determined by comparing velocity constant at two temperatures differing by……………… .

Answer

To determine the temperature coefficient of a reaction, we need to compare the velocity constants at two different temperatures. The steps to arrive at the answer are as follows:

### Step-by-Step Solution:

1. **Understanding Temperature Coefficient**: The temperature coefficient (often denoted as 'μ') is a measure of how the rate of a chemical reaction changes with temperature. It is defined as the ratio of the rate constants (or velocity constants) of the reaction at two different temperatures.

2. **Selecting Temperature Difference**: To determine the temperature coefficient, we typically compare the rate constants at two temperatures that differ by a specific amount. The standard practice is to use a temperature difference of **10 degrees Celsius**.

3. **Mathematical Representation**: The temperature coefficient can be mathematically expressed as:
\[ μ = \frac{K_{T + 10}}{K_T} \]
where \( K_{T + 10} \) is the rate constant at the higher temperature (T + 10°C) and \( K_T \) is the rate constant at the lower temperature (T).

4. **Example**: If we take an example where we have the rate constants at 25°C and 35°C, we can express this as:
\[ μ = \frac{K_{35°C}}{K_{25°C}} \]
This ratio represents the temperature coefficient since the two temperatures differ by 10 degrees Celsius.

5. **Conclusion**: Therefore, the temperature coefficient of a reaction is determined by comparing the velocity constants at two temperatures that differ by **10 degrees Celsius**.

### Final Answer:
The temperature coefficient of a reaction is determined by comparing velocity constants at two temperatures differing by **10 degrees Celsius**.

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