[jHus]

I'm having some trouble finishing some calculations on a chem lab. I am hung up on using specific heat to identify an unknown metal.

We used two Styrofoam cups to make a calorimeter. Here are all the measurements I have taken from lab earlier this week.

• Mass of empty styrofoam cup: 2.17g
• Mass of styrofoam cup with 100.00mL cool water: 100.5g
• Mass of 100.00mL cool water: 98.33g
• Mass of unknown metal: 70.16g

• Temperature of cool water: 20c
• Temperature of metal in boiling water: 83c
• Temperature of cool water/metal: 23c

• Change in temperature: 3c
• Change in metal temperature: 60c

Now I need to find heat energy gained by the cool water:

(not sure if this is right)
Mass of water x change in temp x SH of water

Heat (cal) = 98.33g x 3c x 1.00cal/gc (calories per gram celcius) = 294.99cal

For the next part I am asked to find the specific heat of the unknown metal using the calories calculated above, this is where I get lost.

294.99cal = ____ g x ____ c x (SH) cal/g (calories per gram celcius) = ?

This should give me the specific heat of the metal, this is where I could use some help.

[Borek]

294.99cal = ____ g x ____ c x (SH) cal/g (calories per gram celcius) = ?

This should give me the specific heat of the metal, this is where I could use some help.

Just plug the numbers into the equation and solve for SH.

[jHus]

So, 294.99cal = 70.16g x 3c x (SH) cal/g = 210.48

Then, 210.48/294.99 = 0.713

I did end up getting that far but on the lab I have a list of metals and their specific heats, my unknown metal should be one of these values.

• Aluminum: 0.22
• Iron: 0.108
• Zinc: 0.093
• Copper: 0.092
• Tin: 0.054
• Lead: 0.031

Im confused because my answer seems to be quite a bit off any of those values. 

[Borek]

What was the change in the metal temperature?

[jHus]

change in metal temp was 60c. assuming you mean I used the wrong ΔT?

294.99cal = 70.16g x 60c = 4209.6

294.99/4209.6 = 0.070

Sounds like more of an answer. Must be Tin.

[Borek]

change in metal temp was 60c. assuming you mean I used the wrong ΔT?

Yes, that's what I meant.

294.99cal = 70.16g x 60c = 4209.6

You ate SH, you can't write things like that if you are using equal sign. But other than that you are on the right track.

Disclaimer: I have not checked the numbers, just the logic.

[jHus]

Yeah, I think the way I was writing it out was making it more confusing for me. Thanks a lot for your help.