scrchic00
Posts: 1
Joined: Sun Dec 02, 2007 10:25 am

Heat capacity and density in an unknown element...

Postby scrchic00 » Sun Dec 02, 2007 10:38 am

I can't figure out the IV, DV, and constants and was wondering if anyone could help.

In the lab we are testing what the identity of an unknown metal sample is by measuring change in temperature and mass of the sample as well as change in temperature, mass, and heat capacity of water to find the heat capacity of the unknown sample so that we could identify it. We also measured volume of the unknown sample and mass to find density to help identify it.

Can anyone help?
-scrchic00

staryl13
Former Expert
Posts: 404
Joined: Tue Sep 18, 2007 3:27 pm
Occupation: Research Assistant

Postby staryl13 » Sun Dec 02, 2007 10:58 am

Hi!
One trick to identifying independent and dependent variables is by using the following template:
The Effect of (independent variable) on (dependent variable)
Check out this website, it explains the difference between the two:
http://www.cool-science-projects.com/in ... ables.html
In this case, I think that you are studying the effect of the change in temperature, mass, heat capacity of water on the heat capacity of the unknown sample. Good luck on your project!
"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -Isaac Asimov

Craig_Bridge
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Joined: Mon Oct 16, 2006 11:47 am

Postby Craig_Bridge » Sun Dec 02, 2007 11:41 am

If you have only one unknown metal sample and you have run multiple non-destructive tests on that sample then you have several variable sets, one per test.

You need to view each test separately in terms of deterimining the variable types. In each test, what did you intentionally change or alter (you independentantly changed this) and what did you measure (dependent or resultant variables) and what did you keep constant.

Repeat this thought process for each experiment.

If you have multiple unknown metal samples, then there will be an additional independent variable to identify the sample and a set of resultant variables for each experiment associated with each sample in addition to what you have for a single sample problem.
-Craig

vishwa
Former Expert
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Joined: Sun Nov 11, 2007 8:30 am

Postby vishwa » Sun Dec 02, 2007 12:20 pm

Interesting experiment - initially, I would think that mass and temperature of the sample would be IVs. By the definition of heat capacity, the change in temperature of the sample by a certain interval would require a certain amount of heat being supplied to the sample - this would make the temp. change a DV, with the heat supplied being the control variable or IV.
Change in heat capacity though, would mean a change in the amount of heat required to change the temperature by the same amount - making it a DV. Also, this would depend on the change in mass and/or volume of the sample.


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