Be mindful of the sign for change in product and change in reactant concentration

Question

A + 3B → 2C

If ∆B/∆t is −0.74 M/s, what is ∆A/∆t in M/s?

Be mindful of the sign for change in product and change in reactant concentration.

Answer 1

-∆A/∆t = -1/3 ∆B/∆t = +1/2 ∆C/∆t

-1/3 ∆B/∆t = 0.74 = -∆A/∆t

-∆A/∆t = -0.25 M/s, i.e. it is 1/3 the rate of disappearance of B