Question

If a concentration of HI increases from 0 to 0.001 moldm-3 in 50seconds, what is the rate of reaction?

Answer 1

The average rate is `2xx10^(-5)` mmol/`dm^3` s

Explanation:

The average rate of a reaction over a given time interval is found by determining this ratio:

Rate = `(DeltaC)/(Deltat)`

where `DeltaC` is the change in concentration observed and `Delta t` is the length of the time interval.

With the numbers you provide, this comes to

Rate = `(0.001-0)/50 = 2.0xx10^(-5) "mmol"/(dm^3 s)`

which could be converted into moles per litre (since a cubic decimetre is one litre)

`2xx10^(-8) "mol"/(L s)` (read the unit as "moles per litre per second)