Q5. Which reaction has an enthalpy change equal to the standard enthalpy of formation of lithium fluoride? A Li(g) + F2(g) → LiF(s) B Li+(g) + F–(g) → LiF(s) C Li+(aq) + F–(aq) → LiF(s) D Q6. Two reactions of iron with oxygen are shown. (1) (Total 13 marks) Li(s) + F2(g) → LiF(s) (Total 1 mark) Fe(s) + O2(g) → FeO(s) ΔH = – 272 kJ mol–1 ΔH = – 822 kJ mol–1 2 Fe(s) + O2(g) → Fe2O3(s) What is the enthalpy change, in kJ mol–1, for this reaction? 2 FeO(s) + O2(g) → Fe2O3(s) A +550 B –278 C –1094 D –1372
Q5. Which reaction has an enthalpy change equal to the standard enthalpy of formation of lithium fluoride? A Li(g) + F2(g) → LiF(s) B Li+(g) + F–(g) → LiF(s) C Li+(aq) + F–(aq) → LiF(s) D Q6. Two reactions of iron with oxygen are shown. (1) (Total 13 marks) Li(s) + F2(g) → LiF(s) (Total 1 mark) Fe(s) + O2(g) → FeO(s) ΔH = – 272 kJ mol–1 ΔH = – 822 kJ mol–1 2 Fe(s) + O2(g) → Fe2O3(s) What is the enthalpy change, in kJ mol–1, for this reaction? 2 FeO(s) + O2(g) → Fe2O3(s) A +550 B –278 C –1094 D –1372
The first question requires you to know the definition of formation enthalpy. If you don't know it, look it up.
The second question contains a typo: Fe(s) + O2(g) → FeO(s) is not balanced
The first question requires you to know the definition of formation enthalpy. If you don't know it, look it up.
The second question contains a typo: Fe(s) + O2(g) → FeO(s) is not balanced
Enthalpy of formation is the enthalpy change when 1 mole of a substance is formed from its constituent elements but I’m not sure how that applies to the question
Also for the second one it’s : Fe(s) + 1/2O2 (g) -> FeO(s)
Enthalpy of formation is the enthalpy change when 1 mole of a substance is formed from its constituent elements but I’m not sure how that applies to the question
Also for the second one it’s : Fe(s) + 1/2O2 (g) -> FeO(s)
So, using the definition of formation enthalpy, you can now write down the equation that represents the formation of lithium fluoride. However, there is also a typo in both the question and the answer ...
Two reactions of iron with oxygen are shown. (Total 1 mark) Fe(s) + 1/2 O2(g) → FeO(s) ΔH = – 272 kJ mol–1 2 Fe(s) + 3/2 O2(g) → Fe2O3(s) ΔH = – 822 kJ mol–1 What is the enthalpy change, in kJ mol–1, for this reaction? 2 FeO(s) + 1/2 O2(g) → Fe2O3(s) A +550 B –278 C –1094 D –1372 that is the actual question without typos, can someone explain why the answer is B
Two reactions of iron with oxygen are shown. (Total 1 mark) equation 1: Fe(s) + 1/2 O2(g) → FeO(s) ΔH = – 272 kJ mol–1 equation 2: 2 Fe(s) + 3/2 O2(g) → Fe2O3(s) ΔH = – 822 kJ mol–1 What is the enthalpy change, in kJ mol–1, for this reaction? 2 FeO(s) + 1/2 O2(g) → Fe2O3(s) A +550 B –278 C –1094 D –1372 that is the actual question without typos, can someone explain why the answer is B
In order to generate the required equation, you must take equation 1: Fe(s) + 1/2 O2(g) → FeO(s) reverse it and multiply by 2 to give: 2FeO(s) → 2Fe(s) + O2(g) ΔH = +544 kJ mol–1
In order to generate the required equation, you must take equation 1: Fe(s) + 1/2 O2(g) → FeO(s) reverse it and multiply by 2 to give: 2FeO(s) → 2Fe(s) + O2(g) ΔH = +544 kJ mol–1