A gas mixture 3.67 L in volume contains C2H4 and CH4 is proportion of 2:1 by moles and is at 25∘C and 1 atm. If the ΔHC (C2H4) and ΔHC (CH4) are −1400 and −900 kJ/mol find heat evolved on burning this mixture
185 kJ
Volume of C2H4 = 3.67 × 23 = 2.45Lit
Volume of CH4 = 1.22 Lit
Mole of C2H5 = PV = nRTn = PVRT
= 1 × 2.450.082 × 298 = n = 0.1mole
Mole of CH4 = nCH4 = 1 × 1.220.082 × 298 = 0.05mole
∵ Energy released due to combusting 1 mole C2H4 = 1400 KJ
∴ Energy released due to combusting 1 mole C2H4 = 1400 × 0.1 = 140 kJ
Similar energy released in combusting 0.05 mole
CH4 = −900 × 0.05 = 45
So that heat realized = 140 + 45 = 185 kJ/mole