Thread replies: 8
Thread images: 1
Thread images: 1
Exasperated Chem. Student
Thermochemistry Homework Help 2016-12-04 11:58:22 Post No. 230890
[Report] Image search: [Google]
Thermochemistry Homework Help 2016-12-04 11:58:22 Post No. 230890
[Report] Image search: [Google]
File: Thermochemisery.jpg (57KB, 638x479px) Image search:
[Google]
57KB, 638x479px
Thermochemistry Homework Help
Exasperated Chem. Student
2016-12-04 11:58:22
Post No. 230890
[Report]
Hello. I'll try to keep this post short and to the point.
I have a thermochemistry homework assignment that I am working on, and I have solved all but two of the problems. The issue I am having with both of these problems is that the solutions that I am coming up with for both of them--the same numbers over and over again--are apparently not valid answers.
The problems are as follows:
1. A coffee-cup calorimeter containing 100 mL of H2O is used. The initial temperature of the calorimeter is 23.0 ∘C. If 9.00 g of CaCl2 is added to the calorimeter, what will be the final temperature (in ∘C) of the solution in the calorimeter? The heat of solution ΔHsoln of CaCl2 is −82.8 kJ/mol.
2. Ammonia reacts with oxygen according to the equation:
4 NH3 (g) + 5 O2 (g) → 4 NO(g) + 6 H2O(g) ΔHrxn= −906 kJ
Calculate the heat (in kJ) associated with the complete reaction of 155 g of NH3.
The answer I have for the first problem is 39.0 ∘C and the answer I have for the second problem is -2060 kJ, neither of which are acceptable answers.
>>
OP here again.
I'll show work, if requested. But I'm confident with the formulas and processes I used to get to these answers, and I've cross-checked my answers with other resources that seem to confirm my math. So, I'm feeling quite exasperated and confused at present.
>>
Anyone out there willing to give it a shot with me?
>>
>>230914
i got 2061 for the second one, so 2060 seems perfectly fine. not willing to look up specific heat of water and all that crap for 1, but i'm guessing something is just off in whatever online entry platform you're using.
>>
>>230927
Thank you for the reply. I'm getting -2061.509 kJ myself, to be exact. I've tried entering "2060", "2061", "2062", and the negatives of all those numbers--even 2.06x10^3--but they all just keep getting marked incorrect.
The specific heat of water is 4.186 g/J ∘C, by the way.
>>
>>230890
why does your match look like a scrotum?
>>
>>230933
Ask Google Images.
>>
Wild guess, try using density of water at 23 degree C ~.997, making answer 39.1
Thread posts: 8
Thread images: 1
Thread images: 1