Suppose that stoichiometric amounts of nitrogen gas and hydrogen gas react in a calorimeter to produce 5.00 g of ammonia gas. The calorimeter temperature rises 0.42°C. The calorimeter and water have a combined heat capacity of 32.16 kJ/K. Calculate the heat of formation of ammonia, ΔH°f, in kJ/mol. The formation reaction for ammonia is: 0.5N2(g) + 1.5H2(g) → NH3(g).

Question

aaronq · Answer

q=mC(delta)T

aaronq · Answer

then scale that to 1 mole

anonymous · Answer

What is the work to that.?
I know what to do, but I cannot figure it out. Thanks

aaronq · Answer

you don't need to find the work, only the enthalpy of formation

anonymous · Answer

I need the heat formation though. So what would I put?

aaronq · Answer

q=mC(delta)T

aaronq · Answer

you're finding q

anonymous · Answer

I found q, but how do I scale to one mole?

aaronq · Answer

how many moles of ammonia is 5 grams of ammonia

aaronq · Answer

actually just divide the molar mass of ammonia by 5 grams, then multiply q by that number

anonymous · Answer

Okay, I think I got it. Thank you very much.

aaronq · Answer

no problem

anonymous · Answer

That did not match any of my multiple choice answers. I got 19.883. The closest was 13.

aaronq · Answer

i got 58.0109922

anonymous · Answer

The answer choices are. -46, -13.5, -3.97, 3.97, and 13.5

aaronq · Answer

since the temperature rises, meaning that reaction is releasing heat, so it's exothermic so we're only looking at the negative values

aaronq · Answer

-46 sounds right

anonymous · Answer

Did you work it out?

aaronq · Answer

no i'm not sure why it didn't work out, but i actually know that to be the right value, i'm trying it out hold on

anonymous · Answer

ok thanks a lot

aaronq · Answer

this guy solved it here: http://openstudy.com/study#/updates/510bf8f9e4b0d9aa3c470cb6

anonymous · Answer

You helped a lot. Appreciate it!

aaronq · Answer

no problem, sorry for the confusion