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### Rate constant units

Posted: Sun Mar 18, 2018 9:20 am
What is a general rule of thumb to figure out the units of the rate constant and the initial rate? I'm having trouble figuring them out once we get past fourth order reactions...

### Re: Rate constant units

Posted: Sun Mar 18, 2018 9:43 am
for first order, M/s
for second order, 1/s
for third order, 1/Ms
in general: $M^{1-n}$$time^{-1}$

### Re: Rate constant units

Posted: Sun Mar 18, 2018 10:07 am
An easier way to think of it is just match up your concentrations and their exponents with the rate (which you know is M/s or mol/L*s)

### Re: Rate constant units

Posted: Sun Mar 18, 2018 5:10 pm
write it all out and cancel whatever you can. whats left is your units

### Re: Rate constant units

Posted: Sun Mar 18, 2018 11:43 pm
Another thing I do is whatever the order is, the liters and moles will have an exponent one less than the order.

For fourth order, the rate constant = L^3/ mol^3 * S
For third order, the rate constant = L^2/ mol^2 * s
For second order, the rate constant = L / mol * s

### Re: Rate constant units

Posted: Sun Mar 18, 2018 11:59 pm
In general the constant is M^1-n*time^-1

### Re: Rate constant units

Posted: Tue Feb 19, 2019 12:46 pm
It's helpful to just write all your units out and then see which ones cancel!