Given Thermochemical equation, 2H2(g) + O2(g) arrow 2H2O(l) ; Δ H = -571.6 kJ. Heat of decomposition of water is

Question

Given Thermochemical equation, 2H2(g) + O2(g) arrow 2H2O(l) ; Δ H = -571.6 kJ. Heat of decomposition of water is (A) - 571.6 kJ (B) + 571.6 kJ (C) -1143.2 kJ (D) + 285.8 kJ

Tardigrade Admin · Accepted Answer

Given (i) 2 H 2(g)+ O 2(g) longrightarrow 2 H 2 O ; Δ H=-571.6 kJ At H 2 O (I) longrightarrow H 2(g)+(1/2) O 2(g) ; Δ H=? If reaction (i) is reversed and divided by 2 , the sign of Δ H changes, i.e., Δ H for decomposition of water =+(571.6/2)=285.8 kJ

Q. Given Thermochemical equation, $2 H_{2 (g)} + O_{2 (g)} \to 2 H_{2} O_{(l)}; Δ H = - 571.6 k J$ . Heat of decomposition of water is

$- 571.6 k J$

$+ 571.6 k J$

$- 1143.2 k J$

$+ 285.8 k J$

Given

(i) $2 H_{2} (g) + O_{2} (g) ⟶ 2 H_{2} O; Δ H = - 571.6 k J$

At $H_{2} O (I) ⟶ H_{2} (g) + \frac{1}{2} O_{2} (g); Δ H = ?$

If reaction (i) is reversed and divided by $2$ , the sign of $Δ H$ changes, i.e.,

$Δ H$ for decomposition of water

$= + \frac{571.6}{2} = 285.8 k J$

Q. Given Thermochemical equation, 2H2(g)​+O2(g)​→2H2​O(l)​;ΔH=−571.6kJ. Heat of decomposition of water is

−571.6kJ

+571.6kJ

−1143.2kJ

+285.8kJ