[jamesgxld]

Hey I'm new on here. Could you please help me with this question? CaO(s) + H2O(l) -> Ca(OH)2  Delta H= -65.3kJ
CaO(s)+3C(s)->CaC2(s)+CO(g) Delta H=+462.3kJ
CaC2(s) +2H20(l) -> Ca(OH)2(s)+C2H2(g) Delta H=-126kJ
2C(s)+ O2(g) -> 2CO(g) Delta H=-220kJ 
2H2O(l) -> 2H2(g) +O2(g) Delta H=+572kJ 
How to determine the entalphy of formation of acetylene? Thanks:)

[Borek]

Please read the forum rules.

You have to show your attempts at solving the question to receive help. This is a forum policy.

This looks like a classic application of the Hess law.

[jamesgxld]

Oh sorry. I tried to use algebraic method but I'm not very good at it.

[Enthalpy]

Not everyone operates the same way... For me (but do as you want!):

- I don't apply rules for signs. Thinking every time is safer.
- Third rxn gives C₂H₂ from the difference between C₂Ca and Ca(OH)₂.
- Second rxn, the difference between CaO and C₂Ca.
- First rxn, the difference between CaO and Ca(OH)₂.

Real life is easier than this artificial problem.