Question

calculate the weight in g of 2.5 moles of ethane C2H6. [ C=12,H=1 ]

Answer 1

Wt. Of 1mole ethane 12*2+1*6=30gm wt. Of 2.5 Mole of ethane 30*2.5=75gm

Answer 2

Molecular mass of ethane=2x12+1x6=30
no of moles=given mass/molecular mass
2.5=given mass/30
given mass=2.5x30=75 g