Question

1. the gas phase reaction a + 2b → c has a reaction rate that is experimentally determined to follow the relationship: rate = ka. what is the reaction order of reactant b?

a. 0
b. 1
c. 2
d. 3

Explanation:

Step1: Recall Rate Law Formula

The general rate law for a reaction \( aA + bB
ightarrow cC \) is \( \text{rate} = k[A]^m[B]^n \), where \( m \) is the order with respect to \( A \), \( n \) is the order with respect to \( B \), and the overall order is \( m + n \).

Step2: Compare with Given Rate Law

Given the reaction \( A + 2B
ightarrow C \) and the rate law \( \text{rate} = k[A]^x[B]^y \) (here, the given rate is \( \text{rate} = k[A] \), which implies \( x = 1 \) and \( y = 0 \) for reactant \( B \), because there is no \( [B] \) term. Wait, no—wait, the reaction is \( A + 2B
ightarrow C \), but the rate is given as \( \text{rate} = k[A] \). That means the concentration of \( B \) does not affect the rate, so the order with respect to \( B \) is 0. Wait, but let's check again. The rate law is \( \text{rate} = k[A] \), so the exponent of \( [B] \) is 0 (since it's not present, meaning \( [B]^0 = 1 \)). So the reaction order of reactant \( B \) is 0. Wait, but the options are 0, 1, 2, 3? Wait, the options are: a. 0, b. 1, c. 2, d. 3? Wait, the original problem: "What is the reaction order of reactant B? a. 0, b. 1, c. 2, d. 3". Wait, the rate law is \( \text{rate} = k[A] \), so the rate does not depend on \( [B] \), so the order with respect to \( B \) is 0. So the answer should be 0, which is option a.

Wait, let's confirm. The rate law is determined by the exponents in the rate equation. If the rate is \( k[A] \), that means the concentration of \( B \) has no effect (exponent 0), so the order for \( B \) is 0. So the correct option is a. 0.

Answer:

a. 0