1) The reaction A + B + C = products has a rate law rate = k times A times C squared. Which of the following will result in an increase in the rate constant for the reaction?
#1 - increasing the temperature
#2 - adding a catalyst
#3 - doubling the concentration of reactant C
I think that all three of these answers are correct. Would you agree?
The why would the concentration of any reactant change the rate constant?
I just thought that if the concentration was doubled there would be more molecular collisions which would increase the rate law. So only the first two are correct then?
there is a difference between the rate constant, and the rate. Changing concentration affects rate.
Oh ok I understand, thank you.
So wouldn't a catalyst just speed up the rate too and not the rate constant?
Yes, that's what a catalyst does. It does not change k.
so then answers 2 and 3 are not correct?
That's right. 2 and 3 are not right.
Ok, thank you for your help!!
Yes, all three of the given answers can result in an increase in the rate constant for the reaction. Let's go through each option to understand why:
1) Increasing the temperature: According to the Arrhenius equation, an increase in temperature leads to an increase in the rate constant. This is due to the fact that temperature affects the energy of the reactant molecules, increasing the frequency and effectiveness of collisions between them.
2) Adding a catalyst: A catalyst increases the rate of a chemical reaction by providing an alternative reaction pathway with a lower activation energy. This lower activation energy allows the reactants to proceed faster, resulting in an increase in the rate constant.
3) Doubling the concentration of reactant C: In this particular rate law, the concentration of reactant C is squared, while the concentrations of reactants A and B are only multiplied. Therefore, doubling the concentration of reactant C will result in a quadrupling (2^2) of its effect on the rate, leading to an increase in the rate constant.
So, in conclusion, all three options can increase the rate constant for the reaction.