i just don't get how to do problems with them... for example:
When 1.535 g of methanol (CH3OH) was burned in a constant-volume bomb calorimeter, the water temperature rose from 20.27 oC to 26.87 oC. If the mass of water surrounding the calorimeter was exactly 1000 g and the heat capacity of the bomb calorimeter was 1.75 kJ/oC, calculate the molar heat of combustion of CH3OH. The specific heat of water is 4.184 J/g·oC.
A) -8.17 x 105 kJ/mol
B) -817 kJ/mol
C) 1.88 kJ/mol
D) 817 kJ/mol
E) None of the above.
A 1.300 g sample of benzoic acid (C7H6O2) was burned in a bomb calorimeter. The heat capacity of the entire apparatus, including the bomb, pail, thermometer, and water, was found to be 11,145 J/K. As a result of the reaction, the temperature of the calorimeter and water increased 4.627 K. What is the molar heat of combustion of benzoic acid?
A) 4.84 x 106 kJ/mol
B) -2.96 kJ/mol
C) -4844 kJ/mol
D) 549.1 kJ/mol
E) 51.57 kJ/mol
I know the answers are B and C but I don't know how to get there. does anyone else understand these?
to start with, you find the temperature that the water increased by. this is how much heat energy the burning of the ch3oh produces.
i don't quite remember where to go from there but i will get back to you, i promise.
it has something to do with finding how much heat energy goes into the various parts and some converting between various units, i think.
all in all, it's just another brick in the wall...
I took: AP US Hist, AP Stats, AP Chem
I am taking: AP Calc, AP English, AP Phsics
[SIGPIC][/SIGPIC]
i finally figured it out, but thanks ferris!