Consider the following hypothetical reaction: 2 P + Q → 2 R + S
The following mechanism is proposed for this reaction:
P + P → T (fast)
Q + T → R + U (slow)
U → R + S (fast)
Substances T and U are unstable intermediates. What rate law is predicted by this mechanism?
a. Rate = k[P][Q]2
b. Rate = k[U]
c. Rate = k[P]2[Q]
d. Rate = k[P][Q]
e. Rate = k[P]2

Option C is correct.

Rate = K [P]² [Q]

Explanation:

P + P → T (fast)

Q + T → R + U (slow)

U → R + S (fast)

Overall reaction is

2 P + Q → 2 R + S

Let the rate constant for equations 1, 2 and 3 in the mechanism be k₁, k₂ and k₃.

The rate law is usually obtained from the slow reaction because it is theoretically the rate determining step.

Rate = k₂ [Q] [T]

But for the other reactions in the mechanism, the rate constants can be written as

k₁ = [T]/[P][P] = [T]/[P]²

[T] = k₁ [P]²

k₃ = [U]/[R][S]

[U] = k₃ [R][S]

But, since only [T] is the intermediate in the in the rate determining equation, we substitute for [T] in the rate determining equation.

Rate = k₂ [Q] [T] = k₂ [Q] k₁ [P]² = k₁k₂ [Q] [P]²

k₁k₂ = K

Rate = K [P]² [Q]

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation: