Problem: From the enthalpies of reaction:H2(g) + F2(g) → 2 HF(g), ΔH = –537 kJC(s) + 2F2(g) → CF4(g), ΔH = –680 kJ2 C(s) + 2 H2(g) → C2H4(g), ΔH = +52.3 kJcalculate ΔH for the reaction of ethylene with F2: C2H4 (g) + 6 F2(g) → 2 CF4(g) + 4 HF(g)

FREE Expert Solution

1. H2(g) + F2(g) → 2 HF(g), ΔH = –537 kJ
2. C(s) + 2F2(g) → CF4(g), ΔH = –680 kJ
3. 2 C(s) + 2 H2(g) → C2H4(g), ΔH = +52.3 kJ


C2H4 (g) + 6 F2(g) → 2 CF4(g) + 4 HF(g)


We now need to find a combination of reactions that when added up, gives us the overall reaction.


For (1): We can see that HF(g) is on the same side as the overall reaction. To get the correct coefficient, we can multiply this reaction by 2.

Current reaction sequence:

2 H2(g) + 2 F2(g) → 4 HF(g)            ΔH1 = (–537 kJ) × 2 = –1074 kJ


For (2): We can see that CF4(g) is on the same side as the overall reaction. To get the correct coefficient, we can multiply this reaction by 2.

Current reaction sequence:

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Problem Details

From the enthalpies of reaction:
H2(g) + F2(g) → 2 HF(g), ΔH = –537 kJ
C(s) + 2F2(g) → CF4(g), ΔH = –680 kJ
2 C(s) + 2 H2(g) → C2H4(g), ΔH = +52.3 kJ
calculate ΔH for the reaction of ethylene with F2: C2H4 (g) + 6 F2(g) → 2 CF4(g) + 4 HF(g)

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