Question

The heat of combustion of carbon to CO₂ is -393.5 kJ/mol. The heat released upon formation of 35.2 g of CO₂ from carbon and oxygen gas is

(a) + 315 kJ

(c) - 3.15 kJ

(b) - 630 kJ

(d) - 315 kJ

Answer 1

Ans: (None) 

Sol: Given : $C_{(s)} + O_{2(g)} \to CO_{2(g)}, ΔH = - 393.5 kJ/mol$

$⇒$ Amount of heat released on formation of 

$44 g \text{ } CO_2 = 393.5 kJ$

∴ Amount of heat released on formation of 

$35.2 g \text{ } CO_2 = {393.5\over44}\times35.2 = 314.8 ≈ 315 kJ$