Question

A mixture contains 80% H2 and 20% O2 by mass.what is the average molecular mass of the mixrure

Answer 1

this % means 80 g H2 and 20 g O2 in 100 g Sol.
80% H2 means moles of H2= 80÷2=40 moles
20% O2 means moles of O2=20÷32=0.625 moles
Total moles in mix.= 40.625 moles
40.625 moles of have mass =100 g
so 1 mole has mass= molecular mass= 100÷40.625=2.46 g