Catalysts Answers

1

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Which is the best definition of activation energy?

A

the energy required to end a chemical reaction

B

the energy required to bind a substrate to an active site

C

the energy required to form or break the bonds of reactant molecules

D

the energy required to re-form bonds in product molecules

2

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What is a substrate?

A

a molecule that acts as a catalyst

B

a place on the enzyme where the reaction occurs

C

a place on the product where the enzyme fits

D

a reactant that is catalyzed by an enzyme

3

How does a catalyst work?

A

by increasing the temperature of a chemical reaction

B

by decreasing the pressure of a chemical reaction

C

by increasing the concentration of reactants in a reaction

D

by decreasing the activation energy of a reaction

4

What must happen before a chemical reaction can begin?

A

The activation energy must be exceeded.

B

The activation energy must be reached.

C

The concentrations of products and reactants must be equal.

D

The concentration of reactant molecules must be reduced.

5

A researcher is designing a laboratory experiment to determine whether the inorganic substance A affects the rate of a reaction between two colored liquids, X and Y. When the reaction is complete, the liquid is clear. The reaction between X and Y is similar to one used by manufacturers to produce certain chemicals in factories.Which method would best answer his question about reaction rate and what will he find out about substance A?

A

First, he should measure the final temperature of the liquid when X and Y react without substance A. Then, he should measure the final temperature when he adds substance A to X and Y. He will find out if substance A is a catalyst.

B

First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is a catalyst.

C

First, he should measure the final temperature of the liquid when X and Y react without substance A. Then, he should measure the final temperature when he adds substance A to X and Y. He will find out if substance A is an enzyme.

D

First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is an enzyme.

6

A substance that influences the reaction but does not participate in the reaction is a

A

catalyst

B

reactant

C

product

D

substrate

7

Which term describes an enzyme?

A

substrate

B

reactant

C

catalyst

D

product

8

A student wants to create a liquid volcano. The student observes bubbles in the soft drink prior to opening it. The student first proceeds to open the soft drink bottle and place it on the floor.Next the student drops candy tablets into the drink at a continuous pace. The student notices a very powerful reaction in which the candies, still intact, are pushed out of the soda as the drink fizzes and starts to bubble.In this scenario, what would be the catalyst?

A

The candy tablets being added to the drink.

B

The gasses being released when the drink was first opened.

C

The liquid in the container.

D

The container that holds the liquid.

9

Which statement correctly describes a chemical reaction?

A

Reactants come out of a reaction.

B

Energy is always released.

C

Bonds between atoms break and reform.

D

Products go into a reaction.

10

The lock-and-key mechanism refers to

A

the complementary shapes of an enzyme and a substrate.

B

the attractive forces between an enzyme and a substrate.

C

the ability of an enzyme to lower the activation energy of a reaction.

D

the ability of an enzyme to “unlock” the products of a reaction.

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