Which statement about catalysts and enthalpy is true?

Which statement about catalysts and enthalpy is true?

• A. Catalysts lower the overall enthalpy change.
• B. Catalysts lower activation energy but do not change the overall enthalpy change.
• C. Catalysts increase the activation energy.
• D. Catalysts change the final products.

Answer: (B)

A catalyst provides an alternative reaction pathway with a lower activation energy, so the rate of the reaction increases at a given temperature. The overall enthalpy change (the energy difference between reactants and products) is determined by the bonds in the reactants and products and is not altered by a catalyst. Catalysts don’t change what is formed, they just help it get formed faster. They also speed up both forward and reverse reactions, leaving the equilibrium position and the energy difference between reactants and products unchanged. So the statement that best fits this is: catalysts lower activation energy but do not change the overall enthalpy change. The other ideas would imply changing the final products or the energy landscape itself, which isn’t what a catalyst does, or suggest a higher activation energy, which is the opposite of what catalysts achieve.

A catalyst provides an alternative reaction pathway with a lower activation energy, so the rate of the reaction increases at a given temperature. The overall enthalpy change (the energy difference between reactants and products) is determined by the bonds in the reactants and products and is not altered by a catalyst. Catalysts don’t change what is formed, they just help it get formed faster. They also speed up both forward and reverse reactions, leaving the equilibrium position and the energy difference between reactants and products unchanged.

So the statement that best fits this is: catalysts lower activation energy but do not change the overall enthalpy change. The other ideas would imply changing the final products or the energy landscape itself, which isn’t what a catalyst does, or suggest a higher activation energy, which is the opposite of what catalysts achieve.