experimental techniques Flashcards
1
Q
time
A
stopwatch/stopclock
2
Q
temperature
A
thermometer
3
Q
mass
A
electronic balance
4
Q
volume
A
- fixed volume of liquid: pipette
- variable volume of liquid between 0-50 cm3: burette
- approximate values: measuring cylinder
5
Q
how does chromatography work
A
different substances have different solubilities so will travel at different rates
6
Q
formula for rf
A
distance moved by compound/distance moved by solvent
7
Q
how to find invisible chromatograph substances
A
chemicals called locating agents can be sprayed on the chromatogram to make these samples visible to the naked eye
8
Q
purification methods
A
- seperating funnel
- filtration
- crystallisation
- fractional distillation
- simple distillation
9
Q
seperating funnel
A
- can be used to seperate unmixable liquids
- allow the 1st liquid to collect. THen dispose off the middle layer which contains a mixture of both liquids. Then collect the second liquid
10
Q
filtration
A
-seperate an insoluble solid from a liquid
11
Q
crystallisation
A
seperate soluble solid from liquid
12
Q
fractional distillation
A
- used to seperate two mixable liquids
- principle is the difference in boilingn points ot different liquids
- the liquid with the lower boiling point gets collected first upon heating
- the prescence of a fractionating column ensures that the only vapours witht he liquid of the lower boiling point pass into the condenser while the other vapours condense due to the glass beads and fall back into the beaker
- while one liquid is getting collected, the temperatures shown by the thermometer will not change and thus when the temperature changes we know the first liquid has been collected
13
Q
simple distillation
A
- seerate soluble solid froma solvent which can also be obtained unlike in crystallization
- misture is heated, liquid evaporates and travels through condenser, condenses and collects on other side of condenser
