Heat of combustion of methane is - 800 kJ . What is the heat of combustion for 4 × 10-4 kg of methane ?

Question

Heat of combustion of methane is - 800 kJ . What is the heat of combustion for 4 × 10-4 kg of methane ? (A)  -800 kJ  (B)  -3.2 × 104 kJ  (C)  -20 kJ  (D)  -1600 kJ

Tardigrade Admin · Accepted Answer

underset16 gCH4+2O2 → CO2 +2H2O ; Δ Hc = -800 KJ ∵ Heat of combustion of 16 × 10-3 kg CH 4=-800 kJ ∴ Heat of combustion of 4 × 10-4 kg CH 4 will be =-(800 × 4 × 10-4/16 × 10-3) =-20 kJ

Q. Heat of combustion of methane is $- 800 k J$ . What is the heat of combustion for $4 \times 1 0^{- 4} k g$ of methane ?

$- 800 k J$

$- 3.2 \times 1 0^{4} k J$

$- 20 k J$

$- 1600 k J$

$16 g C H_{4} + 2 O_{2} \to C O_{2} + 2 H_{2} O; Δ H_{c} = - 800 K J$

$∵$ Heat of combustion of $16 \times 1 0^{- 3} k g$

$C H_{4} = - 800 k J$

$∴$ Heat of combustion of $4 \times 1 0^{- 4} k g C H_{4}$ will be

$= - \frac{800 \times 4 \times 1 0 ^{- 4}}{16 \times 1 0 ^{- 3}}$

$= - 20 k J$

Q. Heat of combustion of methane is −800kJ . What is the heat of combustion for 4×10−4kg of methane ?

−800kJ

−3.2×104kJ

−20kJ

−1600kJ