MHT CET 2017 Chemistry Solved Paper

(c) Work done in a chemical reaction,
W = -ΔngRT
Where, Δng = number of moles of gaseous products - number of moles of gaseous reactants.
Reaction involved in combustion of ethane is,
C2H6(g)+

7

2

O2(g) → 2CO2(g)+3H2O(l)
∴ Δng=2−4.5=−2.5
W=(2.5mol) (8.314JK−1mol−1) × 300 K
=6235.5J=6.2355KJ
1 mole of C2H6=30g of C2H6
Work done during combustion of 30 g ofC2H6 = 6.2355 kJ
∴ Work done during combustion of 90g of C2H6 =

6.2355×90

30

= 18.7065 kJ = 18.71 kJ