For each of the following cases, identify the order with respect to the reactant

Question

For each of the following cases, identify the order with respect to the reactant, A. Case (A ? products) Order Number The half-life of A increases as the initial concentration of A decreases. Number A twofold increase in the initial concentration of A leads to a fourfold increase in the initial rate. Number A twofold increase in the initial concentration of A leads to a 1.41-fold increase in the initial rate. Number The time required for [A] to decrease from [Ajo to [Alo/2 is equal to the time required for [A] to decrease from [Alo/2 to [Alo/4. Number The rate of decrease of [A] is a constant.D

Explanation / Answer

1. Increase in half life for decrease in concentration of A is only possible for order 2 for A.

2. 2-fold increasing in concentration of A making a 4-fold increase in rate. Rate is proportional to [A]^2, since 2^2=4. Therefore, order is 2.

3. 2-fold increase in the initial concentration of A, increase the rate by 1.41-fold.

(A2/A1)^n =R2/R1. => (2/1)^n = 1.41 => n log 2 = log 1.41 => n = log 1.41/log2 = 0.4956. Hence, order is 0.4956 ~ 0.5

4. Since the same time is required for each 1/2-fold decrease of the amount of A, that indicates the half-life for A is constant and independent of initial concentration of A. This is 1st order reaction.

5. The rate of decrease of A is constant indicates d[A]/dt = constant, i. e. the rate is independent of initial concentration of A. Hence, it is zero order reaction. Rate = (rate constant). [A]^0 = constant.

Related Questions

Navigate

• Browse (All)
• Browse F
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.