PYQs Homework Notes Mocks Board Daily Homework MHT-CET Chemistry Asked again Enthalpy of combustion of acetylene from enthalpies of formation The same question, asked 2 times: 21 Apr 2025 S2*, 15 May 2026 S2. Every wording below, oldest first.
Try each one first, then open its answer.
Question 1 21 Apr 2025 S2
56 Calculate standard enthalpy change of reaction
C 2 H 2 ( g ) + 5 2 O 2 ( g ) ⟶ 2 C O 2 ( g ) + H 2 O ( l ) C_{2}H_{2(\text{ }g)}+\frac{5}{2}O_{2(\text{ }g)}\longrightarrow 2CO_{2(\text{ }g)}+H_{2}O_{(l)} C 2 H 2 ( g ) + 2 5 O 2 ( g ) ⟶ 2 C O 2 ( g ) + H 2 O ( l ) , if
Δ f H ∘ ( C O 2 ) = − 393 k J m o l − 1 Δ f H ∘ ( H 2 O ) = − 286 k J m o l − 1 Δ f H ∘ ( C 2 H 2 ) = 227 k J m o l − 1 \begin{gathered}\Delta_{f}H^{\circ}\left( CO_{2} \right)= - 393\text{ }kJ{\text{ }mol}^{- 1} \\ \Delta_{f}H^{\circ}\left( H_{2}O \right)= - 286\text{ }kJ{\text{ }mol}^{- 1} \\ \Delta_{f}H^{\circ}\left( C_{2}H_{2} \right)= 227\text{ }kJ{\text{ }mol}^{- 1}\end{gathered} Δ f H ∘ ( C O 2 ) = − 393 k J m o l − 1 Δ f H ∘ ( H 2 O ) = − 286 k J m o l − 1 Δ f H ∘ ( C 2 H 2 ) = 227 k J m o l − 1 A. -650 kJ
B. -1950 kJ
C. -1299 kJ
D. -2598 kJ
Tap an option to check your answer.
Show answer
Question 2 15 May 2026 S2
6 Calculate the standard enthalpy of combustion of C 2 H 2 ( g ) \mathrm{C_2H_2}(g) C 2 H 2 ( g ) ,
C 2 H 2 ( g ) + 5 / 2 O 2 ( g ) → 2 C O 2 ( g ) + H 2 O ( l ) \mathrm{C_2H_2}(g) + 5/2\,\mathrm{O_2}(g) \rightarrow 2\mathrm{CO_2}(g) + \mathrm{H_2O}(l) C 2 H 2 ( g ) + 5/2 O 2 ( g ) → 2 C O 2 ( g ) + H 2 O ( l )
[ Δ f H 0 ( C O 2 ) = − 390 k J m o l − 1 [\Delta_f H^0(\mathrm{CO_2}) = -390\ \mathrm{kJ\ mol^{-1}} [ Δ f H 0 ( C O 2 ) = − 390 kJ mo l − 1 , Δ f H 0 ( H 2 O ) = − 285 k J m o l − 1 \Delta_f H^0(\mathrm{H_2O}) = -285\ \mathrm{kJ\ mol^{-1}} Δ f H 0 ( H 2 O ) = − 285 kJ mo l − 1 and Δ f H 0 ( C 2 H 2 ) = 225 k J m o l − 1 ] \Delta_f H^0(\mathrm{C_2H_2}) = 225\ \mathrm{kJ\ mol^{-1}}] Δ f H 0 ( C 2 H 2 ) = 225 kJ mo l − 1 ] A. Δ c H 0 ( C 2 H 2 ) = − 1290 k J m o l − 1 \Delta_c H^0(\mathrm{C_2H_2}) = -1290\ \mathrm{kJ\ mol^{-1}} Δ c H 0 ( C 2 H 2 ) = − 1290 kJ mo l − 1 B. Δ c H 0 ( C 2 H 2 ) = − 645 k J m o l − 1 \Delta_c H^0(\mathrm{C_2H_2}) = -645\ \mathrm{kJ\ mol^{-1}} Δ c H 0 ( C 2 H 2 ) = − 645 kJ mo l − 1 C. Δ c H 0 ( C 2 H 2 ) = − 1935 k J m o l − 1 \Delta_c H^0(\mathrm{C_2H_2}) = -1935\ \mathrm{kJ\ mol^{-1}} Δ c H 0 ( C 2 H 2 ) = − 1935 kJ mo l − 1 D. Δ c H 0 ( C 2 H 2 ) = − 2580 k J m o l − 1 \Delta_c H^0(\mathrm{C_2H_2}) = -2580\ \mathrm{kJ\ mol^{-1}} Δ c H 0 ( C 2 H 2 ) = − 2580 kJ mo l − 1 Tap an option to check your answer.
Show answer
