Question

For a certain reaction A → products a plot of ln[A] vs. time produces a straight line with a slope of −3.0×10−2 s−1. Which of the following statements is or are true?: The reaction follows first-order kinetics. The rate constant for the reaction is 3.0×10−2 s−1. The initial concentration of [A] was 1.0 M. For a certain reaction a plot of ln[] vs. time produces a straight line with a slope of . Which of the following statements is or are true?: The reaction follows first-order kinetics. The rate constant for the reaction is . The initial concentration of [] was 1.0 . Only one of the statements is true Statements I and II are true Statements I and III are true Statements II and III are true All three statements are true

Answer 1

Answer:

Statements I and II are true.

Explanation:

Let us consider the reaction A → products.

Which of the following statements is or are true?

I. The reaction follows first-order kinetics. TRUE

The expression for a first-order reaction is:

ln[A] = ln[A]₀ - k.t    [1]

where,

[A] is the concentration of the reactant A at certain time t

[A]₀ is the initial concentration of A

k is the rate constant

t is the time

If the plot of ln[A] vs. t A is a straight line, it means that the reaction follows a first-order kinetics.

II. The rate constant for the reaction is 3.0×10⁻² s⁻¹. TRUE.

In [1], ln[A]₀ is the intercept and -k the slope of the linear equation. Thus,

-k = −3.0×10⁻² s⁻¹

k = 3.0×10⁻² s⁻¹

III. The initial concentration of [A] was 1.0 M. FALSE.

Since we do not have information about the intercept in the plot of ln[A] vs. t, we do not have enough information to calculate the initial concentration of A.

Statements I and II are true.