I'm either using the wrong formulas or using the right formula in the wrong way...
Why don't you tell
us what formula you're using, so we can see where you may be going wrong.
Likewise show us your working on the slope of the graph. It looks about right to me.
On a more general point, you are assuming that "Rate = k[A]" means d[A]/dt = -k[A], in which case your answers to the first part are correct. However, "rate of reaction", unless more specifically defined, usually means 1/νi
]/dt, where νi
is the stoichiometric coefficient of reagent Ri
(positive for products, negative for reactants). Thus for your reaction as written
Rate = -1/2*d[A]/dt = -1/4*d[ B]/dt = d[C]/dt = 1/3*d[D]/dt
In this case [A]/[A]0
The problem with this is that before 1.2575 min all the B (the limiting reagent) is gone, so the question can't be answered. (Unless that is supposed
to be the answer, but I doubt it.)