[theengulfer]

When 3.25 g of sodium hydroxide (NaOH) was dissolved in 50.00 g of water a value of 10.50oC was obtained for ΔT.

Calculate the molarity of the sodium hydroxide solution. (I have, = 1.62)

Calculate the value (calories) for the heat of solution of 3.25 g of NaOH.

Calculate the number of calories that would be produced if one mole of sodium hydroxide was dissolved. (ΔHsolnNaOH)

Would anyone care to please help me with this? I have to have it to be allowed into lab and I can't figure it out after hours of trying.

I've tried answers for the second part around 525, they are not accepted.

[Borek]

You will need a value of the specific heat capacity of the solution. Assuming just that of water would be probably good enough as a first approximation.

[theengulfer]

When I use the heat capacity of the water, it doesn't come out right. Would you do the equation with the water's heat capacity so I can see if I'm doing it correctly? I would really appreciate it.

[Borek]

Show what you did and we will start from there.

[theengulfer]

I took the moles of NaOH and multiplied them by 4.186, then I multiplied it by 10.5, the change in temperature... no luck.

Applied this approach: http://answers.yahoo.com/question/index?qid=20081018125724AAQjh7o
... wrong.

This approach: http://answers.yahoo.com/question/index?qid=20081102095151AAXXwdI Also gave me a wrong answer...

Why do other people's approaches not work? I'm plugging in my data.

It almost seems like the obvious answer to this would be 10.5 times 50, since 1 calorie changes 1 gram of water by 1 degree celsius. Or am I approaching this wrong?

[Borek]

It almost seems like the obvious answer to this would be 10.5 times 50, since 1 calorie changes 1 gram of water by 1 degree celsius. Or am I approaching this wrong?

This is pretty close, with one important problem. Mass of the solution is not 50 g.

Again, you do everything to not show your work. Not knowing your work, not knowing what results you get, it is impossible to help you find what you did wrong. And not knowing what you did wrong you will never learn how to do it right.

[theengulfer]

I also tried substituting the 53.25g mass in instead of the 50g. I was still wrong.

To try to answer the problem I used the moles of NaOH in the solution times 10.5, but I just don't know what the Cp would be. I think if I had that I could figure this out. Maybe. Is it the same to find how much heat in calories it would take to heat the water up? Should I consider the sample to be 53.25g when multiplying with the mass? I just don't see how I keep getting this wrong, it's a different version of the same problem, and applying the strategies I see everywhere else, it still doesn't work. i've tried the problem so many times, there are too many different ways to include here. I've tried 22 different methods -- I've had 22 different answers and they are all rejected by the system.

At this point I just want to be able to answer the question because if I can't answer it, I can't attend the lab meeting at my university. I'm so tired that I can barely even think at this point, I stayed up all night.

[Borek]

You are still making us guess what you did. Sounds like you are just juggling numbers. Is it so hard to SHOW YOUR WORK? "I tried to plug 7 instead of 18" doesn't mean anything without a context.

Sorry, but so far you are just wasting your and our time.