Question

Calculate heat evolved for combustion of 13 gm of acetylene (C₂H₂).

Given: \[\ce{C2H2_{(g)} + 5/2O_{2(g)}-> 2CO_{2(g)} + H2O_{(l)} \Delta_{(c)}H^{0} = - 1300 kJ}\]

Answer 1

 \[\ce{C2H2_{(g)} + 5/2O_{2(g)}-> 2CO_{2(g)} + H2O_{(l)} \Delta_{(c)}H^{0} = - 1300 kJ}\]

Molar mass of C₂H₂

= 2C + 2H = 2(12) + 2(1)

= 24 + 2 = 26 gm

From the given equation,

26 gm of C₂H₂ = − 1300 kJ

∴ 13 gm of C₂H₂ = x

∴ x = `(-1300 kJ xx 13 gm)/(26 gm)`

− 650 kJ

∴ On combustion of 13 gm C₂H₂,

− 650 kJ heat is evolved.