How Do You Calculate Specific Heat and Identify Unknown Substances?

[lynn0808]

Need help... Dont know how to solve correctly.

a) Determine the amount of energy to raise the temperature of 18kg of carbon from -5celsius to 17celsius.

b) 200g of a certain substance absorbs 7320J of energy and experienced a temperature rise form 5celsius to 30celsius. By calculating its 'C' value, identify as near as possible, the unknown substance.

here's some work I did

delta t= 17-5=12Celsius.
M=18kg
C=709j/kg
energy=cXmXdelta t
709J/kg.K X 18kg X12K
energy=3.28 KJ
=3.3 X10^2?

how do you solve for b. I don't know how to do it. Is this working correct?

 

[hage567]

For (a), please check your delta t.

For (b), you use the same equation you did for (a). You solve for c, the specific heat capacity. The idea is to find this value and look it up in a table and see what material it corresponds to.