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Hess's Law

#### Q. Given: 2NH 3(g) + 3N 2O(g) => 4N 2(g) + 3H 2O(l) ΔH = -1010 kJ 4NH 3(g) + 3O 2(g) => 2N 2(g) + 6H 2O(l) ΔH = -1531 kJ What is the enthalpy change for the reaction : N2 + 1/2O2 => n2O(g)? A. -813.6 kJ B. -510.3 kJ C. -303.3 kJ D. +207.0 kJ E. +82.0 kJ

Solved • Mar 30, 2020

Hess's Law

#### Q. Consider these hypothetical chemical reactions: 1. A ⇌ B, Δ G= 11.9 kJ/mol 2. B ⇌ C, Δ G= -30.3 kJ/mol 3. C ⇌ D, Δ G= 9.20 kJ/mol What is the free energy, ΔG, for the overall reaction, A ⇌ D? Express your answer with the appropriate units.

Solved • Mar 1, 2020

Hess's Law

#### Q. Find ΔH° for BaCO39s) => BaO(s) + CO2(g) given that 2 Ba(s) + O29g) => BaO(s) ΔH° = -1107.0 kJ Ba(s0 + CO2(g) + 1/2 O2(g) => BaCO3(s) ΔH° = -822.5 kJ A. -1929 kJ B. -1376.0 kJ C. -284.5 kJ D. 269.0 kJ E. 537 kJ

Solved • Mar 23, 2020

Hess's Law

#### Q. 8. Calculate the enthalpy of decomposition of aluminum chloride in the following reaction: 2AlCl3 (s) → 2Al (s) + 3Cl2 (g) Use the following four equations: a) 2Al(s) + 6HCl(aq) → 2AlCl3(aq) + 3H2(g) ΔH°f = −1049 kJ/mol b) HCl(aq) → HCl(g) = ΔH°f = 74.8 kJ/mol c) H2(g) + Cl2(g) → 2HCl ΔH°f = -1845 kJ/mol d) AlCl3(s) → AlCl3(aq) ΔH°f = -323 kJ/mol

Solved • Feb 26, 2020

Hess's Law

#### Q. 4. Calculate the enthalpy of decomposition of phosphorus oxychloride in the following reaction: 10Cl3PO(g) → P4O10(s) + 6PCl5(g) Use the following four equations: a) 4PCl3(g) → P4(s) + 6Cl2(g) ΔH°f = +1225.6 kJ/mol b) P4(s) + 5O2(g) → P4O10(s) ΔH°f = -2967.3 kJ/mol c) PCl5(g) → PCl3(g) + Cl2(g) ΔH°f = +84.2 kJ/mol d) PCl3(g) + 1/2O2(g) → Cl3PO(g) ΔH°f = -285.7 kJ/mol

Solved • Feb 26, 2020

Hess's Law

#### Q. 3. Calculate the enthalpy of formation of carbon dioxide in the following reaction : C (s) + O2 (g) → CO2 (g) Use the following equations: a) H2O (l) → H2 (g) + 1/2O2(g) ΔH°f= +285.8 kJ/mol b) C2H6 (g) → 2C (s) + 3H2 (g) ΔH°f= +84.7 kJ/mol c) 2CO2 (g) + 3H2O (l) → C2H6 (g) + (7/2) O2 (g) ΔH°f= +1560.7 kJ/mol

Solved • Feb 26, 2020

Hess's Law

#### Q. Write the balanced overall equation (Equation 3) for the following process, calculate ΔHoverall, and match the number of each equation with the letter of the appropriate arrow in Figure P6.47. (1) P4 (s) + 6 Cl2 (g) → 4 PCl3 (g) ΔH = -1148 kJ (2) 4 PCl3 (g) + 4 Cl2 (g) → 4 PCl5 (g) ΔH = - 460 kJ

Solved • Mar 13, 2020