In a given diffusion apparatus, 15.0mL of HBr gas diffused in 1.0 min. In the same apparatus and under the same conditions, 20.3 mL of an unknown gas diffused in 1.0 min. The unknown gas is a hydrocarbon. Find it's molecular formula.
We first obtain the rate of diffusion of the gases in mLs-1 which is the same as cm3s-1 since 1mL=1cm3. Then we proceed to find the relative molecular mass of the unknown gas by Graham's law of diffusion. After that we proceed to obtain its molecular formula from its molecular mass having previously been told that it is a hydrocarbon (CH). All these processes are shown in the image attached.
