For a reaction: 2A + B → C + D, the following data is collected by experiments:
Set 1: A=500, B=2, t1/2=30, t7/8=90
Set 2: A=3, B=400, t1/2=10, t7/8=70
Set 3: A=6, B=800, t1/2=a, t7/8=b
Se

Question

For a reaction: 2A + B → C + D, the following data is collected by experiments:
Set 1: A=500, B=2, t1/2=30, t7/8=90
Set 2: A=3, B=400, t1/2=10, t7/8=70
Set 3: A=6, B=800, t1/2=a, t7/8=b
Set 4: A=250, B=1, t1/2=c, t7/8=d
The value of (a + b + c + d) is

Prashant Kotian · Accepted Answer

Correct answer: 0500. Set 1 (A excess): t7/8 = 3*t1/2, so 1st order in B. Set 2 (B excess): t7/8 = 7*t1/2, so 2nd order in A. Set 3 (B excess, 2nd order in A): [B] doubled, so k_obs doubles. [A] doubled, so t1/2 = 1/(k_obs*A) halves again. Thus t1/2 = 2.5 (a). t7/8 = 7*2.5 = 17.5 (b). Set 4 (A excess, 1st order in B): [A] halved, so k_obs (which depends on A^2) is 1/4th. Thus t1/2 quadruples = 120 (c). t7/8 = 3*120 = 360 (d). Sum = 2.5 + 17.5 + 120 + 360 = 500. Therefore, correct answer is 0500.

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