Hydrogen gas is allowed to permeate through a thin plastic membrane that is 76 microns thick.
Concentrations of 0.025 moles/m3 and 0.0025 moles/m3 are maintained on the high and low pressure sides of the membrane, respectively.
If the diffusivity of hydrogen gas molecules in the plastic is 2.2x10-8 m2/s, how many moles of hydrogen gas pass through a 3.0 square meter area of the plastic membrane every hour ?

Hint: We are really computing a flow rate here, rather than a flux. A flow rate is equal to a flux multiplied by an area, and its units are generally count / time.
In this case specifically, the flow rate units will be mol / hour.
In other scenarios, the units could be gram / hour, atom / hour, molecule / hour, etc.