Problem 116 - Chemistry: An Atoms-Focused Approach

Question

The rate of a chemical reaction is too slow to measure at room temperature. We could either raise the temperature or add a catalyst. Which would be a better solution for making an accurate determination of the rate constant?

Step-by-Step Solution

Answer

Answer: Adding a catalyst is a better solution for making an accurate determination of the rate constant in this case, as it can increase the rate of the reaction without increasing the number of side reactions.

Step 1: Effects of Temperature on Rate Constant

Increasing the temperature typically increases the rate of a chemical reaction. According to the Arrhenius Equation: \(k = Ae^{(-Ea/RT)}\), where \(k\) is the rate constant, \(A\) is the pre-exponential factor, \(Ea\) is the activation energy, \(R\) is the gas constant, and \(T\) is the temperature in Kelvin. As the temperature increases, the exponent term becomes larger and the rate constant increases. However, increasing temperature can lead to an increase in the number of side reactions, which can potentially cause inaccuracies in the determination of the rate constant.

Step 2: Effects of Catalysts on Rate Constant

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction. Catalysts work by lowering the activation energy of the reaction, which increases the rate constant according to the Arrhenius Equation. Unlike increasing temperature, adding a catalyst does not increase the number of side reactions.

Step 3: Comparing Temperature and Catalyst Effects on Rate Constant Determination

Both increasing temperature and adding a catalyst can increase the rate constant; however, they have different effects on the reaction. Increasing the temperature can cause an increase in side reactions, potentially leading to inaccuracies in determining the rate constant. On the other hand, adding a catalyst lowers the activation energy, making the reaction faster without increasing side reactions.

Step 4: Conclusion

It can be concluded that adding a catalyst would be a better solution for making an accurate determination of the rate constant in this case. A catalyst can increase the rate of the reaction without increasing the number of side reactions, which allows for a more accurate determination of the rate constant.