# Foo - Need chemistry help

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View Full Version : Need chemistry help

Hickeydog
10-17-08, 05:32 PM
geeze. this chemistry stuff is like the english language: more exceptions than rules. Anyways..

A 27.0 g sample of ethylene glycol, a car radiator coolant, loses 690. J of heat. What was the initial temperature of ethylene glycol if the final temperature is 32.5°C? (c of ethylene glycol = 2.42 J/g·K)

So. The formula is J=(c)(mass)(change in T). So I solved for Ti and came up with Ti=Tf-J/(c)(mass). And I came up with 21.9 degrees centigrade for the answer. Only problem is, this answer is wrong.

Taerom
10-17-08, 05:39 PM
Help me, jschen Kenobi. You're my only hope.

jeff^d
10-17-08, 05:58 PM
You have the change in T correct, but think about the question. If it loses heat, should the initial temperature be higher or lower than the final temperature?

wolfpack
10-17-08, 05:59 PM
do you have a selection of answers?

Taerom
10-17-08, 06:01 PM
42

Hickeydog
10-17-08, 06:01 PM
No selection of answers. And I tried + and -. both are wrong.

Hickeydog
10-17-08, 06:02 PM
42

42. what? I need that decimal..

wolfpack
10-17-08, 06:04 PM
42 is the answer to everything....ohh boy...you've a lot to learn and i've alot to teach. :D

< snaps fingers > now get back to working on that chemistry!!

Hickeydog
10-17-08, 06:06 PM
yeah. I entered in the 42 and I got within 10% of the correct answer. So 29.1 is definitely out. And I think it's positive.

jeff^d
10-17-08, 06:08 PM
I said you already have the change in temperature correct. Just go the other way.

It's 32.5 plus the difference between 32.5 and your 21.9 answer. I feel...wrong...just giving it to you.

Hickeydog
10-17-08, 06:09 PM
never mind. I figured it out. :notamused:

GOD I FLIPPING HATE CHEMISTRY!!!!! GGGGGGGGGGAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Hickeydog
10-17-08, 06:10 PM
I said you already have the change in temperature correct. Just go the other way.

It's 32.5 plus the difference between 32.5 and your 21.9 answer. I feel...wrong...just giving it to you.

And giving the answer to me would be like giving a crippled guy (such as my proffessor soon-to-be) a wheelchair.

HardyWeinberg
10-17-08, 06:12 PM
43.06

HardyWeinberg
10-17-08, 06:14 PM
This is algebra, not chemistry. It's all about the units/labels.

wolfpack
10-17-08, 06:14 PM
yea...how dang hard was it to get 43.06. that's waht i got too.

deraltekluge
10-17-08, 06:17 PM
never mind. I figured it out. :notamused:

GOD I FLIPPING HATE CHEMISTRY!!!!! GGGGGGGGGGAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!But this really isn't a chemistry problem. It's just a very simple algebra problem, and it is stated more in terms of physics than chemistry, anyway.

jschen
10-17-08, 08:54 PM
Help me, jschen Kenobi. You're my only hope.

People who want help should show their work and explain all their reasoning. And try not to post questions the day after jschen had a long night. But then, who knew that I would end up spending 6 hours at a bar on a Thursday night when I went alone just to grab a quick dinner? :D

jsharr
10-17-08, 11:18 PM
I knew. I called ahead and told the bartender you were coming in.

jschen
10-18-08, 12:07 AM
No wonder they didn't seem shocked!