catalyst vs. specific rate constant

[shal3]

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How does a catalyst change the specific rate constant? I thought only temp. changes k. Is it b/c w/ a catalyst we get more collisions b/w the reactant molecules and an increase in collisions gives an increase in temp? so K changes only with temp AND a catalyst?
could someone clearify plz? this is regarding Gchem Q#88 in destroyer.
thnx

 

[osimsDDS]

you should not be confused with Kequillibrium and k as in the rate constant...totally totally different things...

In Keq only temperature will change the value for K because it is temperature dependent.

As for k as the rate constant, it could be changed by a lot of things... concentration, temperature, catalyst...those all change the rate so therefore they will change the rate constant...

 

[Gunacaik]

osimsDDS is correct here, but I just want to possibly clear things up to avoid confusion.

Examples of rate constants are the following... Ka, Kb, Kw, Keq, Ksp (These will be constant and only change when there is changes to Temp.)

Examples of a specific rate constant is the "k" in the equation you already might be familiar with.... Rate = k [X] [Y]
(A catalyst will change the specific rate constant, also other things like osimsDDS mentioned will change it as well)