Homework Help: Chemistry

Posted by Julia on Wednesday, November 30, 2011 at 12:44pm.

a coffee cup calorimeter normally consists of two nested styrofoam cups with a lid. a coffee cup calorimeter of this type contains 125.0 g of water at 20.00 degrees C. A 120.0 g sample of copper metal is heated to 98.0 degrees C by putting it into a beaker of hot water. The copper is then put into the calorimeter and the final temperature of the water and copper is 25.80 degree C

calculate the energy change of the copper metal?

Chemistry - DrBob222, Wednesday, November 30, 2011 at 12:55pm
heat lost by Cu = heat gained by H2O.
q = heat gained by water = mass H2O x specific heat H2O x (Tfinal-Tinitial).

OR, heat lost by Cu is
mass Cu x specific heat Cu x (Tfinal-Tinitial)
Chemistry - Julia, Wednesday, November 30, 2011 at 7:42pm
still dont get it
Chemistry - Julia, Wednesday, November 30, 2011 at 7:49pm
q= 20.00 C =125.0g x 98.0 C x 25.80 C -20.00??
Chemistry - DrBob222, Wednesday, November 30, 2011 at 8:54pm
Well, it's a funny question, at least in the wording. Questions of this type USUALLY ask for the final T or give the final T and ask for the initial T. Still others give both final T and initial T and ask for specific heat or the mass of the metal or the mass of water. In this case, however, the problem give mass, I assume they intend you to look up the specific heats (of Cu or H2O) and it gives final T and initial T. It asks for energy (which I translate as heat)
"Still don't get it" isn't very helpful. you need to tell us what you problem is. My first response gives you my rationale and I see no point in repeating what I wrote above. The numbers are not what you have placed in what appears to be a random order.
q = heat lost by copper = energy lost by copper = mass copper x specific heat copper x (Tfinal-Tinitial).

mass copper = 120.0 g
specific heat copper--That isn't given in the problem. I assume you are look it up in tables in your text and/or notes.
Tfinal = 25.80 C
Tinitial = 98.0
Solve for q.

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