Question

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

Answer:

[AB] = 0.66M

Explanation:

rate = change in concentration/time

Initial concentration of AB = 1.5M

Let the concentration of AB after 10.3s be y

Therefore, rate = 1.5 - y/10.3

The rate equation is given as

rate = k[AB]^2 = 0.2y^2

0.2y^2 = 1.5 - y/10.3

2.06y^2 = 1.5 - y

2.06y^2 + y - 1.5 = 0

Using the quadratic formula

y = [-1 + or - √(1^2 -4×2.06×-1.5)/2(2.06)]

The value of y must be positive

y = (-1 + √13.36)/4.06 = -1+3.66/4.06 = 2.66/4.06 = 0.66

Concentration of AB after 10.3s is 0.66M