Chemistry problem on finding heat capacity of calorimeter.

Question

At constant volume, the heat of combustion of a particular compound is –3200.0 kJ/mol. When 1.789 g of this compound (molar mass = 159.54 g/mol) was burned in a bomb calorimeter, the temperature of the calorimeter (including its contents) rose by 8.701 °C. What is the heat capacity (calorimeter constant) of the calorimeter?

 

 

Last question on my chemistry homework, have been trying for ages and just can't seem to get the right answer. I appreciate anyone who offers their assistance. :)

Answer 1

First you need to know the amount of heat given off by the substance based upon the mass given to you.

 

1.789 g X (159.54 g/mol) X (-3200 KJ/mol) = -35.88 KJ given off by the combustion of this substance.

 

Knowing that thte heat of reaction is equal to the negative heat of the calorimeter (heat absorbed by the water), the negative sign for (-35.88 KJ) turns to positive.

 

Then, manipulating the equation Q=CΔT to the equation C= Q/ΔT we can now solve for the heat capacity.

 

C= 35.88 KJ/ 8.701°C = 4.124 KJ/°C

 

That should be it, good luck!