# Homework Help: Law of thermodynamics

1. Apr 10, 2006

### rcs

I am confused on how to find out the heat of combustion of solid citric acid to water and carbondioxide that is deltaH 296 -1986 kJ/mol. I need to figure out the heat liberated when 10g of citric acid is totally combusted at 298k? *a) At constant pressure?? at constant volume?? and why is it not necessary to specify the pressure in part a?

2. Apr 10, 2006

### rcs

hello can one give me some input

3. Apr 11, 2006

### Hootenanny

Staff Emeritus
HINT: Think about converting your mass into moles. (what units is $\Delta H$ given as)?