A3 Energy Changes In Industry

Question 1

Enthalpy change definition

Answer 1

The change in heat energy at constant pressure

Question 2

What are the set of standard conditions for enthalpy measurement

Answer 2

• 100kpa
• 1 atmosphere (1atm) pressure
• temp of 298k (25c)

Further conditions:
- reactants and products must be in the physical states (solid, liquid, gas)
- any solutions have a conc of 1 mol dm -3

Question 3

Calculating an enthalpy change

Answer 3

^H = ^U + P^V

^H = enthalpy change (Kjmol-1)
^U= change in internal energy (kj)
P= pressure (Kpa)
^v= change in vol (m3)