How Smart Are You Guys?

[Mr.Helms]

An aluminum bolt has a mass of 21.3 g. It is heated then placed into 839 g of water in a copper calorimeter cup with a mass of 137 g. The initial temperature of the water and the copper cup is 16 oC. The bolt, water and cup arive at an equilibrium temperature of 18.4 oC. What was the temperature in degrees celcius of the bolt before it was placed in the water?

 

[Mr.Helms]

I used this formula and got wrong answer, need help.

Tf = (m1C1T1 + m2C2T2) / (m1C1 + m2C2)

And got 541.3 Degrees C. What is wrong.?

 

[russ_watters]

I see three masses in the problem statement and you only have two in your equation...

 

[arunma]

It's never a good idea to write a one line answer, because this will usually give incorrect results. First observe that the heat (heat, not temperature) lost by the bolt is equal to the heat gained by the calorimeter and the water. Figure out how to express the heat loss and the heat gain in terms of temperature. Pay careful attention to the sign of your delta T's. And then finally, solve for the desired quantity.

 

[tim_lou]

sounds like homework to me.