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Enthalpy of Formation

Q. Consider the reaction 2 Al2O3(s) → 4 Al(s) + 3 O2. ΔH = +3339.6 kJ/mol What is ΔH for the formation of one mole of Al2O3(s) from the elements? 1. -679.2 kJ 2. -1669.8 kJ 3. -3339.6 kJ 4. +3339.6 kJ 5. +1669.8 kJ

Solved • Apr 22, 2020

Enthalpy of Formation

Q. What would be the signs of ΔH for the reaction CH4(g) → CH3(g) + H(g) 1. ΔH < 0 2. ΔH = 0 3. ΔH > 0 4. Cannot tell from information given

Solved • Apr 22, 2020

Enthalpy of Formation

Q. How much energy is involved in the formation of 5 grams of rust?

Solved • Apr 23, 2020

Enthalpy of Formation

Q. For which one of the following reactions is ΔH0 for the reaction equivalent to ΔH0,f of the product? a. PCl3 (g) + ½ O2 (g) ⇌ POCl3 (g) b. CaO (s) + SO2 (g) ⇌ CaSO3 (s) c. Al (s) + 3/2 O2 (g) + 3/2 H2 (g) ⇌ Al(OH)3 (s) d. ½ N2O (g) + ¼ O2 (g) ⇌ NO (g)

Solved • Apr 23, 2020

Enthalpy of Formation

Q. Use standard enthalpies of formation to calculate ΔH°rxn for the following reaction: N2O4 (g) + 4 H2 (g) → N2 (g) + 4 H2O (g) Note: ΔH°f (N2O4 (g) = + 9.16 kJ/mol. Be sure your answer contains the correct number of significant figures, is in units of kJ/mol (but do not include the units themselves in your submitted answer), and has the correct sign

Solved • Apr 20, 2020

Enthalpy of Formation

Q. 9.) Calculate ΔH for the reaction: CH4(g) + 4 Cl2(g) -> CCl4(g) + 4 HCl(g) Use the following reactions and ΔH’s. C(s) + 2H2(g) -> CH4(g) ΔH = -74.6 kJ C(s) + 2 Cl2(g) -> CCl4(g) ΔH = -95.7 kJ H2(g) + Cl2(g) -> 2 HCl(g) ΔH = -92.3 kJ

Solved • Apr 17, 2020

Enthalpy of Formation

Q. hydrazine is a liquid often used as rocket fuel. Upon combustion, it yield nitrogen gas and liquid water. If 24,00g sample of N2H4 evolved 465.6kJ of heat during combustion, calculate the molar enthalpy change for combustion (kJ/mol) of hydrazine

Solved • Apr 17, 2020