If
[R]1  and [P]1 are the concentrations of R and P respectively at time t1
and [R]2 and [P]2 are their concentrations at time  t2 then,
Dt
=
t2 – t1
D[R]
=
[R]2 – [R]1
D [P] =
[P]2 – [P]1
The square brackets in the above expressions are used to express
molar concentration Rate of disappearance of R
[
]
Decrease in concentration of R
R
=
Time taken
t
= −∆
∆
(3 1)
3 1
3