How does an enzyme lower the $E$_a barrier in a chemical reaction?

• A. By changing the equilibrium position of the reaction
• B. By providing an alternative reaction pathway with a lower $E$_a
• C. By increasing the temperature of the reaction
• D. By increasing the concentration of reactants

Answer: (B)

Verified step by step guidance

1. Understand the concept of activation energy: Activation energy is the minimum energy required for a chemical reaction to occur. Enzymes lower this energy barrier, making it easier for the reaction to proceed.
2. Recognize the role of enzymes: Enzymes are biological catalysts that speed up reactions without being consumed. They achieve this by providing an alternative pathway with a lower activation energy.
3. Explore how enzymes provide an alternative pathway: Enzymes bind to substrates and stabilize the transition state, reducing the energy required to reach it. This is often depicted as a lower peak in the energy profile of the reaction.
4. Consider the effect on reaction rate: By lowering the activation energy, enzymes increase the rate of reaction, allowing it to proceed faster under the same conditions.
5. Clarify misconceptions: Enzymes do not change the equilibrium position of a reaction, nor do they increase the temperature or concentration of reactants. Their primary function is to lower the activation energy.