Simulation · Chemistry · Class 11
Bomb or open cup: ΔU or ΔH?
From the lesson Calorimetry in Thermodynamics. Change the values and watch what happens.
Bomb or open cup: ΔU or ΔH?Chemistry · Class 11
The idea behind it
NCERT § "Measurement of ΔU and ΔH: Calorimetry"
- Energy changes are measured by calorimetry: the reaction is run in a vessel immersed in a known amount of liquid, and the heat released or absorbed is found from the temperature change and the calorimeter's heat capacity.
- A bomb calorimeter is a sealed steel vessel of constant volume, so no pressure-volume work is done and it measures ΔU.
- In a bomb calorimeter the sample is burnt in pure oxygen, and the heat given out is found from the rise in temperature of the surrounding water.
- Reactions carried out at constant (atmospheric) pressure in a simple calorimeter give q_p, which is ΔH.
- To convert a bomb calorimeter ΔU into ΔH, use ΔH = ΔU + Δn_gRT with gaseous species only.