Thermochemistry help!?!?
 

I've had 3 midterms (brain is fried), and I don't want to make the drive all over campus tomorrow. I figured there's someone on here that kinda knows what they're talking about.

It's a simple heat of combustion problem.

High-purity benzoic acid (C6H5COOH; Delta Hcomb = -3327 kJ/mol) is a combustion standard for calibrating bomb calorimeters. A 1.221-g sample burns in a calorimeter (head capacity = 1365J/degree c) that contains exactly 1.200kg of water. What temperature change is observed (in either C or K)?

Now, obviously the specific heat capacity of water is 4.184J/g*k

I guess I'm just stuck on how to set up the equation, that is all. I'm off to read about John Snow's mapping of Cholera... oh joy!!!


Colin

Re: Thermochemistry help!?!?
 

All i can say is good luck buddy.

Re: Thermochemistry help!?!?
 

that not that hard, same stuff i did in grade 12 chem, i forget it all now. but it wasnt that hard.

Re: Thermochemistry help!?!?
 

Yeah, it's been 4 years since I took highschool chem. It's just a simple manipulation of equations, but I'm drawing a blank.

Re: Thermochemistry help!?!?
 

Wish I could help ya buddy, but I haven't taken college chem in 4 years. And I'm still in college for 2 more years! :S

Re: Thermochemistry help!?!?
 

God I'm a moron.

Simple as hell.

-q sample = q calorimeter

heat capacity X delta t (benzoic acid) + heat capacity X delta T (water) = (3227kj/mol X (1.221g benzoic acid / 122.118g/mol)) = 5.053E0 = delta T

God damn that feels good :6

Re: Thermochemistry help!?!?
 

Your missing the amount of grams per mol of benzoic acid. That would help.

Re: Thermochemistry help!?!?
 

It's called a periodic table, look at it ::)

Re: Thermochemistry help!?!?
 

The sad thing here is that your problem doesn't require any chemistry or physics at all. It's simple algebra.

Study up on math son :1. You're lacking in that dept if can't set up equations simply by looking at the units involved.

I mentioned that because it was a piece of info that was lacking. Whether you get it by looking at the peridoc table (pointless) or by just looking up the chemical itself is your problem.

Re: Thermochemistry help!?!?
 

It was my confusion with specific heat that was the problem, not my ability to manipulate equations. Either way, I figured it out (which, if you would have read my post, you would have hopefully figured out). Eat a dick, faggot. ::)