Help! Kinetics and the Rate of Formation???

For the following reaction, write expressions for the rate of formation of each of the products.
3 A + 2 B + 2 C → D + 3 E + 4 F

1 Answer
Truong-Son N.
Feb 4, 2018

Well, by definition, #D# has the rate of reaction. It's a product, with a coefficient of 1.

#r(t) = +1/1(Delta[D])/(Deltat)#

How do we suppose we equalize all the rates? In forward reactions, reactants cannot appear. Products cannot disappear.

So some human intervention is necessary... aka, normalization.

There are #color(red)(3)# #A# and #color(red)(2)# #C# reactants, and #color(red)(4)# #F# products for every #1# #D# product. Thus,

#overbrace(color(red)(-)1/color(red)(3)(Delta[A])/(Deltat) = [ . . . ] = color(red)(-)1/color(red)(2)(Delta[C])/(Deltat))^("reactants") = overbrace(+1/color(red)(1)(Delta[D])/(Deltat) = [ . . . ] = +1/color(red)(4)(Delta[F])/(Deltat) )^"products" = r(t)#

And with that, #A#, which disappears three times as fast as #D# appears, now is scaled such that it equals the rate of reaction. So how is this done for the rest of the substances in solution?

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