experimental techniques

Question 1

time

Answer 1

stopwatch/stopclock

Question 2

temperature

Answer 2

thermometer

Question 3

mass

Answer 3

electronic balance

Question 4

volume

Answer 4

• fixed volume of liquid: pipette
• variable volume of liquid between 0-50 cm3: burette
• approximate values: measuring cylinder

Question 5

how does chromatography work

Answer 5

different substances have different solubilities so will travel at different rates

Question 6

formula for rf

Answer 6

distance moved by compound/distance moved by solvent

Question 7

how to find invisible chromatograph substances

Answer 7

chemicals called locating agents can be sprayed on the chromatogram to make these samples visible to the naked eye

Question 8

purification methods

Answer 8

• seperating funnel
• filtration
• crystallisation
• fractional distillation
• simple distillation

Question 9

seperating funnel

Answer 9

• 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

Question 10

filtration

Answer 10

-seperate an insoluble solid from a liquid

Question 11

crystallisation

Answer 11

seperate soluble solid from liquid

Question 12

fractional distillation

Answer 12

• 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

Question 13

simple distillation

Answer 13

• 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