Question 1

A catalyst lowers the activation energy barrier, which is the maximum amount of energy required during a collision.

Accepted Answer

The answer of A catalyst lowers the activation energy barrier,...

Question 2

What is the advantage of a homogeneous catalyst versus a heterogeneous catalyst in a reaction?

Accepted Answer

Every particle of a homogeneous catalyst is able to react because it is in the same phase as the reactants.

Question 3

How do homogeneous catalysts mix with reactant solutions?

Accepted Answer

Homogeneous catalysts mix thoroughly with reactant solutions because they are in the same phase (solid, liquid, or gas) as the reactants, allowing for efficient interaction and catalysis.

Question 4

How are heterogeneous catalysts separated from a reaction's products?

Accepted Answer

Heterogeneous catalysts are separated from the products of a reaction through filtration because they are in a different phase (solid) than the reaction mixture (usually liquid or gas).

Question 5

How does the concentration of a reactant influence a zero-order reaction?

Accepted Answer

In a zero-order reaction, the rate of reaction is constant and does not depend on the concentration of the reactant. This means that changes in the concentration of the reactant do not affect the rate of the reaction.

Question 6

The oxidation of ethanol (the alcohol found in alcoholic beverages) by the human body is what type of reaction?

Accepted Answer

The oxidation of ethanol by the human body is a zero-order reaction because the rate of reaction is constant and does not depend on the concentration of ethanol. This means that the body processes ethanol at a constant rate, regardless of the amount present.

Question 7

What enzyme catalyzes the oxidation of ethanol in the body?

Accepted Answer

Alcohol dehydrogenase (ADH) is the enzyme responsible for catalyzing the oxidation of ethanol to acetaldehyde in the body, which is a crucial step in the metabolism of alcohol.

Question 8

What is an enzyme?

Accepted Answer

Enzymes are large biomolecules that act as catalysts within living systems, speeding up chemical reactions without being consumed in the process.

Question 9

Enzyme catalysis is a common class of what type of reaction?

Accepted Answer

The answer of Enzyme catalysis is a common class of...

Question 10

How are zero-order reactions accelerated?

Accepted Answer

Zero-order reactions have a constant rate that does not depend on the concentration of the reactant(s). They can be accelerated by adding a catalyst, which lowers the activation energy required for the reaction to proceed but does not affect the reaction order itself.

Question 11

In the reaction N₂ + 3 H₂ → 2 NH₃, the addition of nitrogen to the reaction does not speed up the reaction rate. What type of reaction can this be considered with respect to nitrogen?

Accepted Answer

The reaction is considered a zero-order reaction with respect to nitrogen because the addition of nitrogen does not affect the rate of the reaction, indicating that the rate is independent of the concentration of nitrogen.

Question 12

In a certain reaction, the concentration of a single reactant is doubled and the rate goes up by a factor of 4. What is the order of the reaction with respect to that reactant?

Accepted Answer

The reaction is second order with respect to that reactant because when the concentration is doubled, the rate increases by a factor of 4 ($2^2$), indicating a second-order dependency.

Question 13

If a reaction has two reactants, and doubling the concentration of one of them doubles the reaction rate, while doubling the concentration of the other leaves the reaction rate unchanged, what is the order of the reaction?

Accepted Answer

The reaction is first order with respect to the first reactant because doubling its concentration doubles the reaction rate, indicating a direct proportionality. It is zero order with respect to the second reactant because changing its concentration does not affect the reaction rate.

Question 14

What happens to the rate of a first-order reaction when a reactant concentration is doubled?

Accepted Answer

For a first-order reaction, the rate is directly proportional to the concentration of the reactant. Therefore, if the concentration of a reactant is doubled, the rate of the reaction also doubles.

Question 15

What does collision theory predict will occur when reactant concentration is increased?

Accepted Answer

Increasing the concentration of reactants typically leads to an increase in the frequency of collisions between reactant molecules, which according to collision theory, increases the rate of the reaction.

Question 16

When cocaine is eliminated from a human body, reaction concentration drops much faster at the outset than at later times. Of what type of reaction is this indicative?

Accepted Answer

This behavior is indicative of a first-order reaction, where the rate of reaction is directly proportional to the concentration of the reactant. In the context of cocaine elimination, this means that when there's more cocaine in the body, it's eliminated faster, and as the concentration decreases, the rate of elimination slows down.

Question 17

If a reaction rate doubles when the reactant concentration doubles, even when catalyzed by an enzyme, what type of reaction is it?

Accepted Answer

This behavior is characteristic of a first-order reaction, where the rate of reaction is directly proportional to the concentration of one reactant.

Question 18

What type of reaction order do most pharmaceuticals follow?

Accepted Answer

Most pharmaceuticals follow first-order kinetics, where the rate of reaction is directly proportional to the concentration of the reactant.

Question 19

What is the symbol for half-life?

Accepted Answer

The symbol for half-life is $t_{\frac{1}{2}}$, which is represented by choice C. This notation is commonly used in physics and chemistry to denote the time required for a quantity to reduce to half its initial value.

Question 20

If a person takes a pain reliever with a 2.5 hour half-life at 1:00 P.M., at what time will three half-lives have expired?

Accepted Answer

Three half-lives of 2.5 hours each total 7.5 hours. Starting from 1:00 P.M., 7.5 hours later is 8:30 P.M.

Quiz 11: Applications of Chemical Kinetics