Topic 8: Energetics Flashcards
1
Q
What are standard conditions ?
2
A
- 100kpa
- 298k
2
Q
What’s the standard enthalpy change of reaction ?
3
A
Is enthalpy change when the reaction occurs in the molar quantities shown in chemical formula
- standard states and conditions
3
Q
What’s the standard enthalpy change of formation ?
3
A
- enthalpy change when 1 mole of substance
- is formed from it constituent element
- with all reactants and products in standard states and conditions
4
Q
What’s enthalpy change of combustion ?
3
A
- enthalpy change when 1mole of substance
- is COMPLETELY BURNT in oxygen
- all reactant and products in standard states and conditions
5
Q
What’s standard enthalpy change of neutralisation ?
3
A
- enthalpy change when 1 mole of water is formed in a reaction
- between acid and alkali
- standard conditions
6
Q
How do you find amount of energy taken in or out ?
2
A
Q=mc🔼t
Measured in Joules
7
Q
How do you calculate 🔼H ?
2
A
-Q/n ( limiting reagent )
In KJ/mol
8
Q
Which way do arrows point in Hess cycle - formation ?
2
A
- from constituent elements upwards
9
Q
Which way to arrows point on Hess cycle -combustion ?
2
A
- downwards - substance to oxides
10
Q
What is bond enthalpy ?
2
A
- enthalpy change to break one mole of covalent bonds in gas phase ?
11
Q
What’s enthalpy of formation of elements ? (1)
A
0
12
Q
Main sources of error in calorimeter experiments ?
3
A
- heat loss
- sensitivity of equipment
- human error
13
Q
Limitation of calorimeter ?
4
A
- SHC OF CAlorimeter ignored
-incomplete combustion
-heat loss to surroundings
-evaporation if methanol /water from
CAlorimeter
