Effects on Rate constant

[Kstar007]

Why doesn't volume have an effect on the rate constant. If pressure has an effect, I would think that volume also has an effect?

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[DAT Destroyer]

Why doesn't volume have an effect on the rate constant. If pressure has an effect, I would think that volume also has an effect?

Increasing pressure and concentration does indeed influence REACTION RATE, but NOT the rate constant , k. Do not confuse the terms up. The Arrhenius equation is an equation that relates this constant to parameters such as activation energy, solvents, temperature, spatial orientation and catalysis. If you see the rate equation for the Arrhenius equation: k=Ae−Ea/(RT) you can see that the rate constant increases for an increase in temperature (and as activation energy increases, the rate constant decreases. The bottom line here is that concentration never changes the rate constant, and pressure normally does not either. For the DAT exam, this is critical when given a set of data from experiments. From this data, you need to be able to do 3 things..1. Write the rate law 2. Calculate k value..3. Using the SAME k value, calculate the new rate ate different concentrations. I have problems like this in DESTROYER.

I hope this helps.

Dr. Romano

 

[Kstar007]

Thank-you that really helps clear things up!