Question

Enter your answer in the provided box. For the simple decomposition reaction AB(g) → A(g) + B(g) rate = k[AB]2 and k = 0.20 L/mol·s. If the initial concentration of AB is 1.50 M, what is [AB] after 10.3 s?

Answer 1

[AB] is 0.65 M

Step-by-step explanation:

Let the concentration of AB after 10.3s be y

Rate = ky^2 = change in concentration of AB/time

k = 0.2 L/mol.s.

Change in concentration of AB = 1.5 - y

Time = 10.3s

0.2y^2 = 1.5-y/10.3

0.2y^2 × 10.3 = 1.5 - y

2.06y^2 = 1.5 - y

2.06y^2 + y - 1.5 = 0

The value of y must be positive and is obtained using the quadratic formula

y = [-1 + sqrt(1^2 -4×2.06×-1.5)]/2(2.06) = [-1 + sqrt(13.36)]/4.12 = 2.66/4.12 = 0.65 M