1.4 energetics Flashcards
(7 cards)
1
Q
ΔHf - enthalpy of formation
A
enthalpy change when 1 mole of compound is formed from its element in their standard states + conditions
2
Q
ΔHc - enthalpy of combustion
A
enthalpy change when 1 mole of substance burn completely in O2, all substance in their standard states
3
Q
ΔH - enthalpy change
A
heat change in a constant pressure
4
Q
hess law
A
total ΔH independent on route taken
5
Q
whats data book value? why diff?
A
average of diff compound
-heat loss
-incomplete combustion
-evaporation
6
Q
determine ΔH
A
- polystyrene cup + lid to prevent heat lot
- measure initial temp for 3 mis
- measure temp at regular interval for 15 mins
- plot temp against time graph
- extrapolate to point of addition
- find ΔT
7
Q
ΔH equation
A
q=mc ΔT
