Question

21. For a homogeneous first order gaseous reaction
A B +C+D, the initial pressure was P, while
pressure after time it' was P if (P > P.). The
expression for the rate constant K is
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Answer 1

Answer:

Explanation: Look at the derivation given in the NCERT. I've solved this problem after understanding the derivation of NCERT. After that if you find it difficult then see the attachment.

Answer 2

The expression for the rate constant K is K = (2.303/t) log [2P₀/(3P₀- P)].

• The initial pressure is P₀.
• Therefore, the total pressure for the reaction A → B + C + D, at time t = P = P₀ - x + x + x +X

           ⇒ x = (P - P₀)/2

• At equilibrium, P₀ - x = P₀ - (P - P₀)/2 = (3P₀-P)/2
• Hence, for the first order reaction, K = (2.3030/t) log [2P₀/(3P₀ - P)]