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Subject Test Chemistry

Question 15 of 17

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SAT Subject Test

Each of the questions or incomplete statements below is followed by five suggested answers or completions.  Select the one that is best in each case.

Which of the following statements about catalysts is true?

Select an Answer

They increase the value of the equilibrium constant.

Correct Answer: 
No

They increase the amount of product present at equilibrium.

Correct Answer: 
No

They increase the concentration of the reactants.

Correct Answer: 
No

They are permanently altered as the reaction proceeds.

Correct Answer: 
No

They reduce the activation energy of the reaction.

Correct Answer: 
Yes

Catalysts work by providing a new pathway with a lower activation energy for the reaction. Catalysts have no effect on the value of the equilibrium constant, so (A) is not true. If the equilibrium constant does not change then the amounts and concentrations of the reactants and products at equilibrium do not change, so (B) and (C) are not true. A catalyst speeds up a reaction but it is not permanently altered or consumed in the reaction, so (D) is not true.

Question Difficulty: 
hard