# Homework Help: Thermochemistry: Heat of a Solution

1. Jun 29, 2010

### Viralrush

1. The problem statement, all variables and given/known data

The heat of solution of potassium acetate (KC2H3O2) in water is -15.3 kJ/mol.
If 12.7 g of KC2H3O2(s) is dissolved in 525 mL of water that is initially at 22.2 °C, what will be the final temperature (in degrees Celcius) of the resulting aqueous solution?

2. Relevant equations

Unsure. I used:

deltaE = C * deltaT

3. The attempt at a solution

First calculating moles: 12.7g / 98.1417g/mol = 0.1294047281 mol

Secondly, calculating kJ per mole: 0.1294047281 mol * -15.3kJ/mol = -1.97989234kJ -> -1979.89234 J

Third, sub into equation: -1979.89234J / (4.18 J/g * 537.7g) = deltaT

deltaT = -0.880897256
22.2 degrees - 0.880897256 = 21.31910274

The answer is incorrect. I use an online homework system and the following answers are incorrect:

21.3
21.2

2. Jun 30, 2010

### Staff: Mentor

If heat of solution is negative, does it mean heat is produced, or absorbed? And should the final temp be higher or lower than initial?

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methods

3. Jun 30, 2010

### Viralrush

Oh jeeze... thanks. Haha.