Reaction Rates and Activation Energy

The catalyst alters the rate of a chemical reaction by,

• providing an alternative pathway with a lower Ea

• changing the products formed in the direction of the reaction

• providing a surface on which the molecules react

• increasing the frequencies of collisions between molecules

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NGSS.HS-PS1-5

Which of the following are true of reaction rates?

• II+III+IV

• I+IV

• II + III

• I+II+III

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NGSS.HS-PS1-5

Which of the following best describes why increasing temperature increase reaction rate?

• Activation energy is reduced.

• Collisions become more frequent.

• Collisions become more energetic.

• Collisions become more frequent and more energetic.

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NGSS.HS-PS1-5

Which of the following statements about the catalyst is true?

• A catalyst accelerates the rate of reaction by bringing down the activation energy.

• A catalyst does not participate in reaction mechanism.

• A catalyst makes the reaction feasible by making ∆G more negative.

• A catalyst makes equilibrium constant more favorable for forward reaction.

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NGSS.HS-PS1-5

An addition of a catalyst to the following reaction would have what effect?

• A would be increased

• B would be increased

• C would be decreased

• No change

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NGSS.HS-PS1-4

NGSS.HS-PS1-5

Limestone chunks are reaction with hydrochloric acid solution at constant temperature with average speed. If we crash the chunks of limestone into powder how would speed of reaction change?

• Reaction speeds up

• Reaction does not change

• Reaction slows down

• Reaction stops

Which of the following is NOT a factor affecting reaction rate?

• temperature

• catalysts

• particle size

• polarity

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NGSS.HS-PS1-5

Reaction rate means...

• amount of product formed

• speed of reaction

• concentration of reacting particles

• combining reactants with products

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NGSS.HS-PS1-5

Decreasing the particle size increases the reaction rate because

• It makes particles move faster

• It increases the likelihood of collisions with the correct geometry

• It decreases the surface area available to react

• It increases the number of collisions

To slow down a chemical reaction you will do one of the following:

• Place the reactants in hot water

• Place the products in ice bath

• Place the reactants in a ice bath

• Keep stirring the reactants with a stirring rod

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NGSS.HS-PS1-5