At 300 K, the standard enthalpies of formation of (COOH) 2 (s), CO 2 (g) and H 2 O(l) are -821, -393 and -286 kJ/mol, respectively. Which of the following is/are correct for the combustion of oxalic a

Question

At 300 K, the standard enthalpies of formation of (COOH) 2 (s), CO 2 (g) and H 2 O(l) are -821, -393 and -286 kJ/mol, respectively. Which of the following is/are correct for the combustion of oxalic acid(s) at 300 K? (one or more than one correct)

TestHub · Accepted Answer

(COOH) 2 (s) + 1/2 O 2 (g) → 2CO 2 (g) + H 2 O(l). ΔH = 2(-393) + (-286) - (-821) = -251 kJ/mol (a true, and the heat released at constant pressure is 251, so d false). Δn g = 2 - 0.5 = +1.5. ΔU = ΔH - Δn g RT = -251 - 1.5 × 8.314 × 300/1000 = -251 - 3.74 = -254.74 kJ/mol. Heat released at constant volume = 254.74 kJ/mol (c true). -247.26 would come from the wrong sign (b false). Ans (a),(c).

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Options:(select one or more)

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