# Chemical Forums

## Chemistry Forums for Students => High School Chemistry Forum => Topic started by: albert611 on September 08, 2004, 01:10:07 AM

Title: Finding Heat of Formation
Post by: albert611 on September 08, 2004, 01:10:07 AM
How can you find heat of formation if you're given a balanced chamical equation, but none of the heats of formation can be found on a table with common values. can it be found using hess's law?
for example:
CuSO4+2KOH -> Cu(OH)2 + K2SO4
And the problem verbatim:
A 50.0 mL sample of a 1M solution of CuSO4 is mixed with 50.0 mL of 2M KOH in a calorimeter. THe temperature of both solution was 20.2C before mixing and 26.3C after mixing. The heat capacity of the calorimeter is 12.1 j/k. from these data, calculate delta H for the process (chemical eq given above). Assume the sp. heat and density of the solution after mixing are the same as those of pure water.

thank you very much for your help.
Title: Re:Finding Heat of Formation
Post by: Mitch on September 08, 2004, 01:17:10 AM
I'm not sure you need the heats of formation. But they can be found in a book called "CRC Handbook of Chemistry and Physics"
Title: Re:Finding Heat of Formation
Post by: albert611 on September 08, 2004, 08:07:29 AM
How would you find delta H w/o the actual value though?
Title: Re:Finding Heat of Formation
Post by: Demotivator on September 08, 2004, 09:50:31 AM
Heats of formation is a term used for the formation of a compound from its elements. The problem is not about heat of formation but heat of the chemical reaction.
delta H = (delta T)(grams water)(Cw) + (delta T)(Ccal)
Cw is heat capacity of water
Ccal is heat capacity of calorimeter.