.:Bomb-Calorimeter:.

A bomb calorimeter is a type of constant-volume calorimeter used in measuring the heat of combustion of a particular reaction. bomb calorimeters have to withstand the large pressure within the calorimeter as the reaction is being measured. Electrical energy is used to ignite the fuel; as the fuel is burning, it will heat up the surrounding air, which expands and escapes through a tube that leads the air out of the calorimeter. When the air is escaping through the copper tube it will also heat up the water outside the tube. The temperature of the allows for calculating calorie content of the fuel.

In more recent calorimeter designs, the whole bomb,pressurized wiyh excess pure oxygen(typically at 30atm)and containing a known mass of sample(typically 1-1.5g) and a small fixed amount of water(to absorb produced acid gases),is submerged under a known volume of water(ca. 2000ml) before the charge is (again electrically) ignited.The bomb,with sample and oxygen,form a closed system-no air escapes during reaction.The energy released by combustion raises the temperature of the steel bomb,its contents, and the surrounding water jacket. The temperature change in water is then accurately measured. This temperature rise, along with a bomb factor( which is dependent on the heat capacity of the metal bombs parts) is used to calculate the energy given out by the sample burn. A small correction is made to account for electrical energy input, the burning fuse, and acid production ( by titration of he residual liquid). After the temperature rise has been measured, the excess pressure in the bomb is released.

Basically, a bomb calorimeter consist of small cup contain the sample, oxygen, a stainless steel bomb), water, a stirrer, a thermometer, dewar (to prevent heat flow from the calorimeter to the surrounding) and ignition circuit connected to the bomb.

The equation involve to find in bomb-calorimeter:

qsys = qwater + qcal +qrxn

where,

qsys= 0 as there's no heat enter or leaves environment

qwater= mcΔT

qcalorimeter= CcalΔT

Therefore;

qrxn = -(qwater + qcal)