chemistry chapter 1 experimental chemistry

variables

to improve

• accuracy

• reliability

• precision

physical quantities

physical quantities

1cm = 10 mm

Volume

-volumetric flask and measuring cylinder cannot be used for mixing liquids → use beaker

-don’t use volumetric flask for transferring liquids also, it is used for dilation

**always remember to add dps eg 23.00, very important, even if it is a zero, must add the zero dp

** accurate/exactly → always use pipette and burette

prevent parallax error

how are gases collected?

separating solid-solid mixtures

suspension (insoluble solid + liquid)

Filtration

evaporation to dryness

** only if dissolved solid is heat stable

crystalisation

simple distillation

condenser → to cool and condense water vapour into liquid

paper chromotography

travel further= more soluble in the solvent

only have 1 spot —> pure

on start line —> insoluble in solvent

** use vocab like ‘spots’ and ‘moved the same distance’

fractional distillation

• water has not reach boiling state yet to reach high enough to go to condenser (evaporate but not boil yet)

• so go back to flask to continue to boil

purity of substances