Catalysts lower activation energy

Steps:

• Activation energy (Ea) is the minimum energy barrier for reactants to form products.
• Catalysts speed reactions by offering an alternative pathway with reduced Ea.
• Other factors like temperature, concentration, and pressure influence rate via collision theory or equilibrium shifts, not Ea directly.
• Thus, only adding a catalyst targets and decreases Ea.

Why A is correct:

• Catalysts provide a lower-energy reaction pathway, reducing Ea in the Arrhenius equation (k = A e^(-Ea/RT)), which increases the rate constant without being consumed.

Why the others are wrong:

• B: Decreasing temperature slows the rate by reducing molecular energy but leaves Ea unchanged.
• C: Increasing concentration raises collision frequency, boosting rate, but Ea stays the same.
• D: Increasing pressure compresses gases, effectively raising concentration and rate, but does not alter Ea.

Final answer: A