Energetics Flashcards
1
Q
Chemical reactions in which heat energy is given out are…
A
Exothermic
2
Q
Chemical reactions in which heat energy is take in are…
A
Endothermic
3
Q
Q
A
mcΔT
4
Q
ΔH
A
Q/mol
5
Q
Bond-breaking is an…
A
Endothermic process
6
Q
Bond-making is an…
A
Exothermic process
7
Q
Total energy change
A
Bonds broken - bonds made
8
Q
Measuring enthalpy changes in combustion reactions
A
- Measure 100cm3 of water using a measuring cylinder and transfer the water to a copper can
- Take the initial temperature of the water
- Weigh a spirit burner containing fuel with its lid on (the lid should be kept on when the wick is not lit to prevent fuel from evaporating)
- Arrange the apparatus as shown
- Light the wick to heat the water. Extinguish the flame by putting the lid back on once you have a reasonable rise of water temperature (40degrees)
- Measure the maximum temperature of the water
- Weigh the spirit burner again
- Repeat and average
- Change fuel and repeat
9
Q
Measuring enthalpy change in neutralisation, displacement and dissolving reaction
A
- A fixed volume of one reactant is added to the polystyrene cup and the initial temperature is recorded
- An excess amount of the second reactant is added and the solution is stirred continuously
- Measure the maximum temperature of the water
10
Q
c(water)
A
4.18 kJ/mol
