[Isomer]

The following data were collected in an experiment designed to determine the molar heat of solution of pure calcium chloride..

mass of calcium chloride.....11.10 g
mass of styrofoam cups.......7.9
mass of water and styrofoam cups.....110.49 g
initial temp of water.......22.7 degrees celsius
highest temp obtained......40.1 degrees celsius

Determine the molar heat of solution of calcium Chloride.

Here is the formula I think I should use...n^H calcium chloride = mc^t styro + mc^t water

Problem is I can't figure out the ^t of the styrofoam, or the ^ H of the calcium chloride. 2 unknowns don't do me any good. Any ideas how to figure out either one?

[Isomer]

Or am I being overly confident that I have my formula right? 

[Yggdrasil]

Since styrofoam is an insulatory material, you would not expect its temperature to change during the experiment.  So, (Delta)T of the styrofoam is essentially zero, which makes your formula a lot easier to deal with.

[Isomer]

But wouldn't the styrofoam then take on the temperature of the water? Isn't that what happens in a calorimeter? Logically, I know styrofoam can hold something hot andt be fairly cool, but putting the styrofoam as zero isn't making sense. I don't think at this level of chem my teacher would expect us to know that.

[sdekivit]

mass of styrofoam cups.......7.9
mass of water and styrofoam cups.....110.49 g

the only thing you need to know from this data is that you can calculate the mass of water in the calorimeter.

So it's exactly what yggdrasil said

[Donaldson Tan]

heat liberated by solvation = heat absorbed by water + heat absorbed by styrofoam cup

heat absorbed by water = m_water.c_water.dT_water
heat absorbed by cup = m_cup.c_cup.dT_cup

given m_water >> m_cup and dT_water >> dT_cup since styrofoam is an insulator, then heat absorbed by water >> heat absorbed by cup.

Hence, the heat of solvation is approximately equal to the heat absorbed by water corresponding to its temperature increment.

[Isomer]

I found out that there is actually a C value for the styrofoam, so know I have all the proper information to solve this question!

Thanks for the replies.

[billnotgatez]

Isomer-

Could you post the C value you used for styrofoam.
Could you post the C value you used for water.

[Isomer]

C value for water...4.19

c value for styrofoam.....0.30

[billnotgatez]

Thanks