Explain the role of a catalyst in a chemical reaction and its effect on activation energy and heat of reaction. Calculate the average rate of reaction in Experiment 2.

A catalyst increases the rate of a chemical reaction by providing an alternative reaction pathway with a lower activation energy. It does not get consumed in the reaction.

The function of a catalyst in this experiment is to increase the rate of reaction by lowering the activation energy.

The heat of reaction ($\Delta H$) depends only on the initial energy of the reactants and the final energy of the products. It is a state function. A catalyst changes the reaction pathway and activation energy, but it does not change the overall energy difference between reactants and products. Therefore, the heat of reaction remains the same whether a catalyst is used or not.

The heat of reaction in experiment 6 will be EQUAL TO that in experiment 1.

Calculate the average rate of reaction (in mol/min) with respect to zinc for experiment 2 if 1.5 g of zinc is used.
From the table, for Experiment 2:

• Reaction Time = 14 min
• Mass of zinc = 1.5 g (given in the question)
• Molar mass of zinc (Zn) = 65.38 g/mol (This is a standard value, often provided in a periodic table or data sheet. I will use 65.38 g/mol for precision.)

First, calculate the number of moles of zinc:

$$\text{Moles of Zn} = \frac{\text{Mass of Zn}}{\text{Molar mass of Zn}}$$ $$\text{Moles of Zn} = \frac{1.5 \text{ g}}{65.38 \text{ g/mol}}$$ $$\text{Moles of Zn} \approx 0.02294 \text{ mol}$$

Next, calculate the average rate of reaction:

$$\text{Average rate of reaction} = \frac{\text{Change in moles of reactant}}{\text{Time taken}}$$ $$\text{Average rate of reaction} = \frac{0.02294 \text{ mol}}{14 \text{ min}}$$ $$\text{Average rate of reaction} \approx 0.001638 \text{ mol/min}$$

Rounding to three significant figures:

$$\text{Average rate of reaction} \approx 0.00164 \text{ mol/min}$$

The function of the catalyst is to:
13.5.1. Increase the rate of reaction by lowering the activation energy.

13.5.2. The heat of reaction in experiment 6 will compare to that in experiment 1 as: EQUAL TO

13.6. The average rate of the reaction with respect to zinc for experiment 2 is:

$$\text{0.00164 mol/min}$$