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Question

You are studying the reaction:

2 A + B + 3 C --> D + 4 E

If the rate is 2.67 M/min with respect to [A], what is the rate with respect to C?

Answer 1

2A + B + 3C ==> D + 4E

For every 2 moles of A that disappear, 3 mols of C disappear. That is, the rate of disappearance of C is 3/2 or 1.5 times that the rate of disappearance of A.

With that in mind, if the rate of disappearance of A is 2.67 M/min, then the rate of disappearance of C will be 2.67 M/min x 1.5 = 4.01 M/min.

You can write the rates for this reaction as follows:

-1/2∆A/∆t = -∆B/∆t = -1/3∆C/∆t = +∆D/∆t = +1/4∆E/∆t

Thus using only A and C, we have ..

-1/2(2.67 M/min) = -1/3(x)

-1.335 M/min = -1/3 x

x = 4.005 = 4.01 M/min