Question

if the concentration of reactants are expressed in mol/L and time is expressed in seconds, what are the units for the rate constant K?

Answer 1

What is the equation for the rate constant?

Answer 2

rate = k[a][b]

Answer 3

with t on the end

Answer 4

We want to rate to have units of (mole/L)*s right?

Answer 5

Sorry, we want units of mole/L-s

Answer 6

Therefore, the rate constant must have units of \(1/s\)

Answer 7

Assuming the two reactants have reaction orders of 1, the rate constant needs to have units of:
\[\frac{M}{s}=k*M*M\]\[\frac{M}{s}=\frac{1}{M*s}*M*M\]\[\frac{M}{s}=\frac{M}{s}\]Therefore, the rate constant must have units of:
\[M^{-1}s^{-1}\]

Answer 8

Or, alternatively
\[L·mol^{-1}s^{-1}\]