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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: yoyohs on May 20, 2021, 12:41:06 PM

Title: How to find concentration of product when given rate of consumption of reactant?
Post by: yoyohs on May 20, 2021, 12:41:06 PM

This is the sample reaction: A + 2B → 3C + 4D

• The initial concentration of B is 0.0425 mol/L.
• After 12.7 min the concentration of B is 0.0194 mol/L
• The average rate of consumption of reactant A is -1.52x10^-5 mol/L⋅s

Given this information, how to find the concentration of C, which is a product, at 9 min?

I found the reaction rate of B at 9 mins, and converted it to C's reaction rate using mol ratio so far. But I don't think this is the right way to solve because the concentration of B will be different at 9 min, compared to 12.7 min. Any help would be great!

Title: Re: How to find concentration of product when given rate of consumption of reactant?
Post by: Orcio_87 on May 20, 2021, 04:10:20 PM

Reaction can follow different mechanisms:

V = k [ A ] [ B ]

V = k [ A ] [ B ]²

V = k [ B ]

V = k [ B ]²

First and second variants are not important due to context, but still - result will depend on selected variant (3 or 4).

Title: Re: How to find concentration of product when given rate of consumption of reactant?
Post by: penta-d on May 21, 2021, 07:20:02 PM

It looks like they give you enough info in the problem to find the average rate of consumption of reactant B. Compare what you get for that with the given average rate of consumption of reactant A - it might help you better understand what is going on with this.