# Homework Help: Experiment help

1. Apr 18, 2006

### gem0688

Hey ya, I need to design 3 different experiments to find the specific heat capacity of a metal block. I have got 2 but am just stuck for a third. The two i have are:

Method of mixtures

Heat up metal block in a water math, transfer to a cold water bath and observe the temperature rise.

Electrical method

Heat up metal block with a heating rod inserted in, measure voltage, current and temperature every 30 seconds.

I have been trying to find another method, and have found a mechanical method (use a crank to raise a load) but am not sure how that works.

Anyone have any ideas of a possible experiment or how the crank one works?

Thanx

2. Apr 18, 2006

### Hootenanny

Staff Emeritus
You could heat up the bock using a fuel of known chemical composition. Weigh the fuel before and after heating, this will allow you to calculate the energy released during combustion. Measure the temperature of the block before and after heating.

Regards,
~Hoot

3. Apr 18, 2006

### gem0688

Ok so then i can see how much energy has been used to raise the temperature of a certain mass by my change in temperature. ok think i understand that one, thanx, any ideas on how the crank might work too?

4. Apr 19, 2006

### andrevdh

The apparatus is called Callendar's drum (a hollow cylindrical metal drum in which a known quantity of water is inserted or a solid cylindrical metal drum). A band is wrapped around the drum which is rotated at a constant rate (count the amount of revolutions). From one end of the band masses are hung and the other end is kept under tension by a spring balance. The work done by the friction (difference between the tension and weight times the circumference of the drum times the revolutions) on the drum heats it up (measure the temperature increase for the work done by the frictional force). This enables one to calculate the shc of the drum material.

5. Apr 19, 2006

### gem0688

Ok, thanx. So this would not be a suitable method for a solid metal block then because it has to be a hollow cylindrical metal drum. Have you got any ideas about a solid cylindrical metal?

6. Apr 19, 2006

### andrevdh

No, it can be done with a solid drum too.

7. Apr 19, 2006

### gem0688

ohh ok. So the experiment would be as you described it but without the water, instead just the solid drum.

8. Apr 19, 2006

### andrevdh

Yes. The heat transferred to it is a result of the work done by the friction of the band wrapped around it. Determining the mass and resulting temperature rise enables one to calculate the shc of the material.

9. Apr 20, 2006

### gem0688

Do you have any ideas of any other posiible experiments?

So, in the crank experiment, the heat is caused by the work done to overcome the friction, so that is the heat supplied. Then because i know the mass of my metal and i can measure the temperature rise i can put it into the SHC equation:

SHC = heat transfered
Mass x Temperature rise

to get my SHC. Yup?

Think i understand that one now!

thnx

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