The standard heat of formation of carbon disulphide (l) given that the standard heat of combustion of carbon(s) , sulphur(s) and carbon disulphide(l) are -393.3, -293.72 and -1108.76 kJ mol⁻¹ respectively is
(a) 128.02 kJ mol⁻¹
(b) 12.802 kJ mol⁻¹
(c) -128.02 kJ mol⁻¹
(d) -12.802 kJ mol⁻¹
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The standard heat of formation of carbon disulphide (l) given that the standard heat of combustion of carbon(s) , sulphur(s) and carbon disulphide(l) are -393.3, -293.72 and -1108.76 kJ mol⁻¹ respectively is
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- (a) 128.02 kJ mol⁻¹
- (b) 12.802 kJ mol⁻¹
- (c) -128.02 kJ mol⁻¹
- (d) -12.802 kJ mol⁻¹
Answer
- 128.02 kJ mol⁻¹
Explanation
- (i) C(s) + O₂(g) → CO₂(g); ΔH₁ = -393.3 kJ
- (ii) S(s) + O₂(g) → SO₂(g); ΔH₂ = -293.72 kJ
- (iii) CS₂(l) + 3O₂(g) → CO₂ + 2SO₂ ; ΔH₃ = -1108.76 kJ.
On adding (i) and (ii) and subtracting (iii), we get,
C(s) + 2S(s) → CS₂(g), ΔH
- = -393.3 + 2 (-293.72) + 1108.76
- = +128.02 kJ mol⁻¹.
Answered by
1
The standard heat of formation of carbon disulphide (l) given that the standard heat of combustion of carbon(s) , sulphur(s) and carbon disulphide(l) are -393.3, -293.72 and -1108.76 kJ mol⁻¹ respectively is
(a) 128.02 kJ mol⁻¹ ✓✓
(b) 12.802 kJ mol⁻¹
(c) -128.02 kJ mol⁻¹
(d) -12.802 kJ mol⁻¹
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