Which equation should be used for a bomb calorimeter?
Constant-Pressure Calorimetry In contrast, a bomb calorimeter ‘s volume is constant, so there is no pressure-volume work and the heat measured relates to the change in internal energy (ΔU=qV Δ U = q V ).
Does a bomb calorimeter measure delta H directly?
The combustible gas is metered into the calorimeter. Temperatures of all reactants must be controlled. Since the reaction occurs at constant pressure, DcombH is measured directly. Reactants are initially separated.
How do you calculate delta h in a bomb calorimeter?
ΔHC=ΔEC+Δ(nRT) . The temperature of the surroundings (water + room) is typically constant in a bomb calorimetry experiment, as it is done in a huge, probably 2-L water reservoir.
Why is benzoic acid used in bomb calorimeter?
Benzoic acid (C6H5CO2H) is often used for this purpose because it is a crystalline solid that can be obtained in high purity. The combustion of benzoic acid in a bomb calorimeter releases 26.38 kJ of heat per gram (i.e., its ΔHcomb = −26.38 kJ/g).
Why do you need to purge the nitrogen out of the bomb calorimeter?
The purging of nitrogen from the bomb interior eliminates corrections due to the heat of combustion of N2. Close the outlet valve and refill the bomb with 25 atm of oxygen.
What is the most abundant component of dry air at sea level?
nitrogen
What is the heat capacity of benzoic acid?
Constant pressure heat capacity of solid
| Cp,solid (J/mol*K) | 155.2 |
| Temperature (K) | 298. |
| Reference | Andrews, Lynn, et al., 1926 |
| Comment | |
|---|---|
| T = 22 to 200 C.; DH | |
What is benzoic acid?
As a preservative, you will find benzoic acid in beer, chewing gums, sweets, ice cream, jams, jellies, maraschino cherries and margarine. You will also find benzoic acid used in processed foods such as cheeses and meats.
What is the properties of benzoic acid?
Chemical Data
| Benzoic Acid Formula | C7H6O2 or C6H5COOH |
|---|---|
| Molecular Weight/ Molar Mass | 122.12 g/mol |
| Density | 1.27 g/cm3 at 15oC |
| Boiling Point | 523K |
| Melting Point | 395 K |