Chapter 9 - Enthalpy Flashcards
1
Q
Enthalpy
A
➜ a measure of heat energy in a chemical system at constant pressure
2
Q
law of conservation of energy
A
➜ energy cannot be created or destroyed
3
Q
Exothermic
A
➜ energy is released into the surroundings
➜ △H is NEGATIVE
4
Q
Endothermic
A
➜ energy is taken in from surroundings
➜ △H is POSITIVE
5
Q
Standard conditions
A
➜ standard pressure = 101kPa
➜ standard temp = 25°C (298K)
➜ standard conc = 1 mol dm⁻³
6
Q
q = mc△t
A
q = energy (J) m = mass (g) C = specific heat capacity ( 4.18) △t = change in temp
7
Q
Average bond enthalpy
A
➜ the energy required to break one mole of specified type of bond in a gaseous molecule
8
Q
Hess’ Law
A
➜ states that if a reaction can take place by 2 routes and the starting and finishing conditions are the same, the total enthalpy change is the same for each route
