Hey guys, a fellow pre-pharm here. I'm in general chem 1 currently, and we have recently started thermochemistry. I've been doing some practice problems, but I've come across one that's left me stumped. If anyone would care to lend me some insight, it would be much appreciated!

An Al pan(c = 0.902J/gK), weighing 850.0 g, that was being used to boil water has just boiled dry. Assuming the Al pan is at 100.oC what is the final temperature if the pan is placed into 1.00L of water at 20.0oC?

Hey guys, a fellow pre-pharm here. I'm in general chem 1 currently, and we have recently started thermochemistry. I've been doing some practice problems, but I've come across one that's left me stumped. If anyone would care to lend me some insight, it would be much appreciated!

An Al pan(c = 0.902J/gK), weighing 850.0 g, that was being used to boil water has just boiled dry. Assuming the Al pan is at 100.oC what is the final temperature if the pan is placed into 1.00L of water at 20.0oC?

I don't know if I'm right, but here's a shot at it because it's similar to a problem I recently did. You use the formula q=nC (Tf- Ti)...so when looking for the final temperature you have to take into account that you need to heat up the Al pan in order to boil the water so what you're looking for is Tf. The basic outline should be:

Also it says that the water has just boiled dry...so you might need to add a phase change in there i.e. liquid to gas...but I'm not completely sure.

-q(Al pan)=q(water)
so you get
-(850g)(0.902J/gK)(Tf- 373K)=(1.00L <--you have to convert this to grams)(heat capacity of water- this should be given but in my book it says 4.18 J/gC and that's the wrong units so look for it in the right units)(Tf-293)

Then from here it's just algebra, hope this helps and if I'm wrong I'm sorry...

Can someone explain the (100-T_f) and (T_f - 20)? I get the rest, but I don't understand this part. I can do the math, but I'm having comprehending why I do that.

Can someone explain the (100-T_f) and (T_f - 20)? I get the rest, but I don't understand this part. I can do the math, but I'm having comprehending why I do that.

Instead of starting another thread, I have one more simple question to ask.

How do I find the number of joules in one Btu (Btu- amount of heat required to raise temp of 1 lb of water by 1o F)? I know the answer is 1054 Joules, but I can't figure out how to do the math.

Instead of starting another thread, I have one more simple question to ask.

How do I find the number of joules in one Btu (Btu- amount of heat required to raise temp of 1 lb of water by 1o F)? I know the answer is 1054 Joules, but I can't figure out how to do the math.

The best way to do well in thermochemistry, physical chem, or physics is to take calculus and really try to understand it and do well. Everything after that will be cake.

I'm taking Pchem right now, and it's tough. I had calculus a loooong time ago, so I had to brush up on it a little, but it's helped a lot. Try taking your calculus before you do Pchem, even if your school offers "non-calc" pchem. It really helps to know the calc, or at least to be familiar with it.