For the reaction A + 2 B → 3 C + D, what is the magnitude of the rate of change for [B] when [C] is increasing at 4.6 M/s?

Answer 1

The rate of change for [B] will depend on the order of the reaction with respect to [B], and unless this is an elementary step, the order cannot be determined from the equation.

Rate = k[A]^m[B]ⁿ where k is the rate constant and m and n are the order with respect to A and B, respectively.

This hold for initial rates.

Now, since the question asks for the MAGNITUDE of the rate of change for [B], we can approach the problem as follows:

-dA/dt = -1/2 dB/dt = 1//3 dC/dt = dD/dt

so -1/2 dB/dt = 1/3 dC/dt

1/2 dB/dt = 1/3 x 4.6 M/s = 1.53

dB/dt = 3.1 M/s