Help please. The (change in)H value for the reaction 1/2 O2 (g) + Hg (l) --- HgO(s) is -90.8kj. How much heat is released when 68.2g Hg is reacted with oxygen?

Question

Help please. The (change in)H value for the reaction 1/2 O2 (g) + Hg (l) ---> HgO(s) is -90.8kj. How much heat is released when 68.2g Hg is reacted with oxygen?

joannablackwelder · Answer

Since the ΔH is given for the given reaction, we can write that 1 mol Hg= 90.8 kJ released. So, convert g Hg to moles, then to kJ released. Let me know what you get (or how far you get).

anonymous · Answer

30.9kj!

anonymous · Answer

So the equation wasn't really necessary right? and how did you know mol = kJ?

aaronq · Answer

$\Delta H$ is usually given in kJ/mol (but it could also be given in kJ/g or any other units).

anonymous · Answer

Thank you guys! You two are the best! :D

joannablackwelder · Answer

Good job. No worries. :)

joannablackwelder · Answer

Also, the equation was necessary. If we were asked for how much heat was released for 100 g of O2 being burned we would have to use 1/2 mol O2=90.8 kJ released.

anonymous · Answer

Ohh got it! Thank you very much!

joannablackwelder · Answer

Great! No problem.