A reaction A+B+C-D has the following differential rate law: rate=k[A][B]^2.
a)if the concentration of A is tripled, what happens to the rate?
b) if the concentration of A is doubled and the concentration of C is halved, what happens to the rate?

Thank you

Question

A reaction A+B+C->D has the following differential rate law: rate=k[A][B]^2.
a)if the concentration of A is tripled, what happens to the rate?
b) if the concentration of A is doubled and the concentration of C is halved, what happens to the rate?

Thank you

photon336 · Answer

This reaction the rare is r = k[A][B]^2

This means that the reaction is second order with respect to B and first order with respect to A. Overall we just count the exponents to figure out overall reaction rate 1+2 = 3. This is a third order reaction.

If we triple the [a] --> [3a] and keep the concentration of B constant.
Then your rate should go up by a factor of 3.

photon336 · Answer

The [C] doesn't apply because it simply isn't in our rate law. There is no term for that in what was given in the problem so increasing the concentration of [C] wouldn't do anything.

If you double [A] then you double your reaction rate goes up by a factor of 2.

photon336 · Answer

Rate laws are experimentally determined, by keeping the concentration of one of your substances constant while studying the change in concentration of the other.