Q: Which equation best represents the rate of a reaction in terms of reactant concentration?

$$\text{Rate} = -\frac{\Delta [\text{Reactant}]}{\Delta t}$$

Question 1

Which of the following best describes the rate of a chemical reaction?

Accepted Answer

The change in the amount of reactant or product per unit time.

Question 2

According to collision theory, what must occur for a chemical reaction to take place?

Accepted Answer

Particles must collide with enough kinetic energy.

Question 3

What is the minimum energy that colliding particles must have in order to react called?

Accepted Answer

Activation energy

Question 4

Which equation best represents the rate of a reaction in terms of reactant concentration?

Accepted Answer

$$	ext{Rate} = -\frac{\Delta [	ext{Reactant}]}{\Delta t}$$

Question 5

Which factor does NOT increase the rate of a chemical reaction?

Accepted Answer

Increasing particle size

Question 6

Why does grinding a solid reactant into a fine powder increase the reaction rate?

Accepted Answer

It increases the surface area, allowing more collisions.

Question 7

Which of the following is a real-world example of a catalyst speeding up a reaction?

Accepted Answer

Platinum speeding up the reaction between hydrogen and oxygen to form water.

Question 8

What is an activated complex?

Accepted Answer

An unstable arrangement of atoms at the peak of the activation-energy barrier.

Question 9

Which factor is being applied when salt water is added to the metal alloy in an MRE to increase the rate of rusting?

Accepted Answer

Catalyst

Question 10

What is the effect of an inhibitor on a chemical reaction?

Accepted Answer

It interferes with the action of a catalyst, slowing or stopping the reaction.

Question 11

Which of the following would DECREASE the rate of a reaction?

Accepted Answer

Increasing particle size

Question 12

In the reaction $$	ext{Mg}(s) + 2	ext{H}^+(aq) ightarrow 	ext{Mg}^{2+}(aq) + 	ext{H}_2(g)$$, what would increase the rate of hydrogen gas production?

Accepted Answer

Using powdered magnesium instead of a solid strip.

Question 13

Which statement about catalysts is TRUE?

Accepted Answer

A catalyst is not consumed during a reaction and does not appear as a reactant in the chemical equation.

Question 14

What is the role of enzymes in biological reactions?

Accepted Answer

They act as catalysts to increase the rates of reactions.

Question 15

Which of the following best explains why the reaction rate of carbon with oxygen at room temperature is essentially zero?

Accepted Answer

The activation energy is too high for collisions to break the bonds at room temperature.

Question 16

Which graph best represents an exothermic reaction?

Accepted Answer

A graph where the energy of products is lower than the energy of reactants.

Question 17

A sugar refinery explosion is an example of which factor affecting reaction rate?

Accepted Answer

Particle size (small dust particles increase surface area and reaction rate)

Question 18

Which of the following would most likely slow down a reaction?

Accepted Answer

Adding an inhibitor

Question 19

What happens to the frequency of collisions and reaction rate when the concentration of reactants is increased?

Accepted Answer

Both frequency of collisions and reaction rate increase.

Question 20

Which equation shows the effect of a catalyst on activation energy?

Accepted Answer

$$E_{a,	ext{catalyzed}} \u003c E_{a,	ext{uncatalyzed}}$$

Reaction Rates and Factors Affecting Chemical Reactions

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