[demonat0r]

CaCl2 ~~> Ca(2+) + 2Cl(1-)     change in enthalpy = -81.5kJ

An 11.0g sample of CaCl2 is dissolved in 125g of water with both substances at 25.0 degree C. Calculate the final temperature of the solution assuming no heat lost to the surroundings and assuming the solution has a specific heat capacity of 4.18 J/dgreeC g.

i used the formula heat = (specific heat)(mass of solution)(change in temperature)

So what i did was (4.18 J/dgreC g) (136 g) (Final temp - 25) = 81500 J
i divided both sides by 4.18 and 136 and i got
Final temp - 25 = 143.36
then i added 25 to both sides and i got
Final temp = 168.36 dgre C

but the answer in the book says 39.2 dgre C

did i do something wrong? or is the book wrong?

[enahs]

Your reaction gives the enthalpy per mol. Do you have a mol?

[demonat0r]

Your reaction gives the enthalpy per mol. Do you have a mol?

oh ok i see what went wrong now. thank you very much!