Units of Rate of reaction and Speciflc rate of Reaction Chemistry Notes
Units of Reaction Rate and Specific Reaction Rate (k) :
→ If unit of concentration is mole/litre and unit of time is second or minute or hour, then Unit of reaction rate = moll L-1s-1
= mol L min-1min-1
= mol L-1 hr-1
→ The unit of rate constant can be determined as follows:
aA + bB + cC → Product
Rate of reaction k[A]a [B]b [C]c
= k [concentration]a
[concentration]b [concentration]c
Assuming equal concentrations of A, B and C
= k [concentration]a + b + c …… (1)
∴ The unit of second order reaction is L mol-1s-1
Units of Rate Constant for Gaseous Reactions :
Dimension of k= (atm)1-xs-1
= (bar)1-xs-1
Here, x = Order of reaction.
For first order reaction, (x = 1) = (atm)1-1s-1
= s-1
For second order reaction (x = 2) = (atm)1-2s-1
= atm-1s-1
For zero order reaction (x = 0) – (atm)1-0s-1
= atm s-1