Verify by calculating that (a) 5 moles of CO2 and 5 moles of H2O do not have the same mass. (b) 240 g of calcium and 240 g magnesium elements have a mole ratio of 3:5.

Soln:

• Molar mass of CO2 =12 + 2 x 16= 12 + 32 = 44 g mol^-1

5 moles of CO2 have mass = 44 x 5 = 220 g

Similarly, molar mass of H2O = 2x 1 + 16 = 18 g mol ^-1

5 moles of H2O have mass =18

x 5 = 90 g

It is verified that 5 moles of CO₂ and 5 moles of H₂O are not same.

• Number of moles = w/ atomic weight Atomic weight of Ca= 40 amu

Number of moles in 240g Ca metal 240/ 40 = 6 Number of moles in 240g of Mg metal 240/ 24 = 10 Atomic weight of Mg = 24amu

Ratio 6:10