A catalyst speeds up a chemical reraction by

Options

A. shifting the equilibrium
B. increasing the activation energy
C. initiating the reaction
D. decreasing energy of activation

Answer

To solve the question "A catalyst speeds up a chemical reaction by", we need to understand the role of a catalyst in a chemical reaction. Let's break down the solution step by step:

### Step 1: Define a Catalyst
A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. This means that it can participate in the reaction but is regenerated at the end.

**Hint:** Remember that a catalyst is not consumed in the reaction; it remains unchanged after the reaction.

### Step 2: Understand the Mechanism
Catalysts work by providing an alternative reaction pathway that has a lower activation energy compared to the uncatalyzed reaction. Activation energy is the minimum energy required for a reaction to occur.

**Hint:** Focus on the concept of activation energy and how it relates to the speed of a reaction.

### Step 3: Compare Activation Energies
In a reaction without a catalyst, the activation energy (Ea) is higher. When a catalyst is present, the activation energy (Ea') is lower. This means that less energy is needed for the reactants to convert into products, allowing the reaction to proceed faster.

**Hint:** Visualize the energy profile of a reaction with and without a catalyst to see how the activation energies differ.

### Step 4: Analyze the Options
Now, we can analyze the provided options:
1. It shifts the equilibrium - **Incorrect**: Catalysts do not affect the position of equilibrium; they only speed up the rate at which equilibrium is reached.
2. It increases the activation energy - **Incorrect**: Catalysts actually decrease the activation energy.
3. Initiating the reaction - **Incorrect**: Catalysts do not initiate reactions; they merely speed them up.
4. It decreases the energy of activation - **Correct**: This is the definition of how a catalyst functions.

**Hint:** Eliminate options that do not align with the fundamental properties of catalysts.

### Step 5: Conclusion
Based on the analysis, the correct answer to the question is that a catalyst speeds up a chemical reaction by decreasing the energy of activation.

**Final Answer:** A catalyst speeds up a chemical reaction by decreasing the energy of activation.