If heat of formation of C3H8,CO2 and H2O are -38.2,-94.1 and -48.2kcal respectively. Then calculate heat of combustion of propane:-

Question

If heat of formation of C3H8,CO2 and H2O are -38.2,-94.1 and -48.2kcal respectively. Then calculate heat of combustion of propane:- (A) -423.3kcal (B) +423.3kcal (C) -436.9kcal (D) +436.9kcal

Tardigrade Admin · Accepted Answer

C3H8+5O2 arrow 3CO2+4H2O ΔH=(ΣΔ)fH(.P.)-(ΣΔ)fH(.R.) ΔH=3(.-94.1.)+4(.-48.2.)+38.2 ΔH=-282.3-192.8+38.2 ΔH=-436.9Kcal

Q. If heat of formation of $C_{3} H_{8}, C O_{2}$ and $H_{2} O$ are $- 38.2, - 94.1$ and $- 48.2 k c a l$ respectively. Then calculate heat of combustion of propane:-

$- 423.3 k c a l$

$+ 423.3 k c a l$

$- 436.9 k c a l$

$+ 436.9 k c a l$

$C_{3} H_{8} + 5 O_{2} \to 3 C O_{2} + 4 H_{2} O$
$Δ H = (ΣΔ)_{f} H (P) - (ΣΔ)_{f} H (R)$
$Δ H = 3 (- 94.1) + 4 (- 48.2) + 38.2$
$Δ H = - 282.3 - 192.8 + 38.2$
$Δ H = - 436.9 Kc a l$

Q. If heat of formation of C3​H8​,CO2​ and H2​O are −38.2,−94.1 and −48.2kcal respectively. Then calculate heat of combustion of propane:-

−423.3kcal

+423.3kcal

−436.9kcal

+436.9kcal