An excess of aluminum metal is added to 200.0 mL of 0.025 M solution of CuCl2, reducing the Cu+2 ions to metallic Cu. If the temperature of the solution increases from 25.0 to 27.5 degrees celsius, what is the enthalpy of this reaction per mole of Cu formed? (Specific heat of solution = 4.18 J/gK)

Question

An excess of aluminum metal is added to 200.0 mL of 0.025 M solution of CuCl2, reducing the Cu+2 ions to metallic Cu. If the temperature of the solution increases from 25.0 to 27.5 degrees celsius, what is the enthalpy of this reaction per  mole of Cu formed? (Specific heat of solution = 4.18 J/gK)

a) 2.09 kJ
B) 23.0 kJ
C) 83.6 kJ
D) 418 kJ

I wrote out the equation:
3 CuCl2 + 2Al = 2AlCl3 + 3Cu

There are 0.005 moles of CuCl2 present, so that will result in 0.005 moles of Cu. I found the mass and plugged it into the q=mc(change in T) equation, but got an answer different from those above. Help? Thansk!

bobpursley · Answer

your heat: 200*4.18*2.5 J heat per mole=your heat/(.005) = about 2000/.005J=about 400kJ work it accurately and see if D is correct.

nisse · Answer

23.5