Question

At 518° C, the rate of decomposition of a sample of gaseous acetaldehyde, initially at a pressure of 363 Torr, was 1.00 Torr s^–1 when 5% had reacted and 0.5 Torr s^–1 when 33% had reacted. The order of the reaction is :
(1) 3 (2) 1 (3) 0 (4) 2

Answer 1

Ans. (4)

CH₃CHO → CH₄ + CO

r₁ = 1 torr sec^–1 , when 5% reacted (95% unreacted)
r₂ = 0.5 torr sec^–1 , when 33% reacted (67% unreacted)
r ∝ μ (a – x)^m , m = order of reaction, a–x = unreacted