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If, for the reaction C₁H₃OH(g) + 3O₂(g) → 2CO₂(g) + 3H₂O(l); ΔH = -1364 kJ mol⁻¹; then the ΔH value for 4CO₂(g) + 6H₂O(l) → 2C₁H₃OH(g) + 6O₂(g) would be A - VCE - SSCE Chemistry - Question 4 - 2009 - Paper 1
Question 4
If, for the reaction C₁H₃OH(g) + 3O₂(g) → 2CO₂(g) + 3H₂O(l); ΔH = -1364 kJ mol⁻¹; then the ΔH value for 4CO₂(g) + 6H₂O(l) → 2C₁H₃OH(g) + 6O₂(g) would be A. +2728... show full transcript
Worked Solution & Example Answer:If, for the reaction C₁H₃OH(g) + 3O₂(g) → 2CO₂(g) + 3H₂O(l); ΔH = -1364 kJ mol⁻¹; then the ΔH value for 4CO₂(g) + 6H₂O(l) → 2C₁H₃OH(g) + 6O₂(g) would be A - VCE - SSCE Chemistry - Question 4 - 2009 - Paper 1
Step 1
Calculate ΔH for the reverse reaction
Answer
To find the ΔH value for the reaction involving the formation of ethanol (C₁H₃OH), we first need to reverse the original reaction. The original reaction is negative, indicating it is exothermic:
C₁H₃OH(g) + 3O₂(g) → 2CO₂(g) + 3H₂O(l)
When reversing it, we write:
2CO₂(g) + 3H₂O(l) → C₁H₃OH(g) + 3O₂(g)
Thus, the ΔH for this reverse reaction will be +1364 kJ mol⁻¹.
Step 2
Multiply the reaction coefficients
Answer
The next step will involve scaling the reversed reaction. We need to multiply both sides of the reaction by 2:
2(2CO₂(g) + 3H₂O(l) → C₁H₃OH(g) + 3O₂(g))
This gives:
4CO₂(g) + 6H₂O(l) → 2C₁H₃OH(g) + 6O₂(g)
Since we multiplied by 2, the ΔH for this reaction must also be multiplied by 2:
ΔH = 2 × +1364 kJ mol⁻¹ = +2728 kJ mol⁻¹.
Step 3