Question

Calculate 

(i) Mass in gram of 5.8 mol N₂O 

(ii) Number of moles in 8.0 g of O₂ 

(iii) Molar mass if 11.2 L at STP weight 8.5 g

Answer 1

(i) Molecular mass of N₂O = 2(14) + 16 = 44

Mass = Molecular mass × No. of moles

= 44 × 5.8

= 255.2 g

(ii) Number of moles of

O₂ = \(\frac{Mass\,of\,O_2}{Molecular\,mass\,of\,O_2}\) = \(\frac{0.8}{32}\) = 0.25 mol

(iii) \(\because\) 11.2 L at STP weight = 8.5 g

\(\therefore\) 22.4 L at STP will weight = \(\frac{8.5}{11.2}\) x 22.4

= 17 g mol^-1