Will someone please let me know if this is the right answer for a chemistry problem.?

Question

Calculate the initial temp. of a 15.0 g piece of Cu if placing it in 75.00 g of water raises the temp. from 22.0 degrees celsius to 35.5 degrees celsius. This is what I did, first i found the heat using (q=m*C_s*change in temp.) for mass i used 15.0 + 75.00, i used the specific heat of water, and temp change was 22-35.5= -13.5, so for heat i got -5083.56 J (is that right?) Then I used the same eq. to find initial temp of Cu, my heat (q) was -5083.56J, mass was just mass of Cu 15.0 g, I used specific heat of water (4.184J/g*C), and my change in temp. (this is where i'm not sure i did it right) for final temp i used -13.5 - initial temp, and solved for intial temp. my answer was 65.5 C. Will someone please let me know if i'm right. If i'm not can you please explain to me how i get the answer. Thank you.

Answer 1

Fist the following equation have to be balanced

The heat given up by the copper = the heat received by the water (assume no heat loss)

The heat received by water = mass of water * specific heat if water * temperature rise = 75*4.184*(35.5 - 22) = 4236.3J.

The heat given by copper = mass of copper * specific heat of copper* temperature rise = 15*0.385*(T-35.5)

4236.3= 15*0.385*(T-35.5)

T= (4236.3/15/0.385) +35.5 = 769.06degree C

Answer 2

The Conservation of Energy applies here. All of the heat given up by the copper is gained by the water.

First calculate the heat gained by the water and then secondly go back to the copper.

For the water the mass = 75.00 grams, Cp 4.184J and delta T is 35.5-22.0 = 13.5 oC. Use this to solve for Q.

Now for the Copper, the heat lost is -Q from above (giving up heat is negative Q). The mass is 15.0g, The Cp is the Cp of copper (you need that number) and the delta T is (35.5 - Ti) (Ti is the Initial temperature). Now you can solve for Ti and have the correct answer.

Answer 3

You are right!