Here is a reaction: Cl₂ (g) → 2 Cl (g)

1) Predict if this reaction is endothermic or exothermic

2) Predict if ΔS⁰ is positive, negative or zero

3) Is this reaction spontaneous at all temperature? Explain

Question

Here is a reaction: Cl₂ (g) → 2 Cl (g)

1) Predict if this reaction is endothermic or exothermic

2) Predict if ΔS⁰ is positive, negative or zero

3) Is this reaction spontaneous at all temperature? Explain

| General Chemistry 3

Accepted Answer

1) Chlorine is naturally a diatomic element ⇒ Cl₂ is most stable elemental state

AND this reaction results in the breaking of a bond ⇒ heat taken

⇒ endothermic reaction (ΔH⁰_rxn > 0)

2) The disorder is increasing: from 1 mole of gas to 2 moles of gas

⇒ ΔS⁰_rxn > 0

3) The reaction is spontaneous when ΔG⁰_rxn < 0 ⇒ ΔH⁰_rxn – TΔS⁰_rxn < 0

The reaction is only spontaneous at high temperature (when T > ΔH⁰_rxn/ΔS⁰_rxn)

Final - Question 4 | General Chemistry 3