Calculate the Electron Affinity of F(g) in kJ/mole using Hess' Law?

[greenglasses]

Homework Statement

Calculate the Electron Affinity of F(g) in kJ/mole using Hess' Law.
IE1 + IE2 of Sr(g) is 1580 kj
Hsub of Sr(s) is 144 kJ
Hdiss of F2 is 79 kJ
Hf of SrF2 (s) is -1215 kJ
Hlatt of SrF2 (s) is -2441 kJ

Homework Equations

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The Attempt at a Solution

1. Sr(g)+Sr⁺(g) -> Sr²⁺(g) + Sr⁺(g) + 2e-
2. Sr (s) -> Sr(g)
3. F₂(g) -> 2F(g)
4. Sr(s) + F₂(g) -> SrF₂
5. Sr²⁺(g) + F^-(g) -> SrF2 (s)

I tried to:

flip 5
1/2 * flip 3
flip 1
flip 2
copy 4

but when I did that, I ended up with an extra 1/2 F₂ that I couldn't cancel out. I'm not sure what to do.

 

[DrDu]

In 5. there is a 2 missing before F-