something that only contains one compound or element throughout
boiling point
a chemically pure substance will melt or boil at a specific temperature - you can test for a substances purity by comparing it with the boiling point of that pure substance
Formulations
useful mixtures with a precise purpose - each component is measured exactly and contributes to the properties of the formulation
formulation of paint
pigment, solvent, binder, additives
Paper chromatography
mobile phase = where the molecules can move, this is always a liquid or a gas
stationary phase = where the molecules can't move - a solid or thick liquid
mobile phase
the chemical that spends more time in the mobile phase will move further through the stationary phase
high solubility molecules
will spend more time in the mobile phase
Rf Value
distance travelled by substance/distance travelled by solvent
test for chlorine
chlorine turns damp litmus paper white
test for oxygen
relight a glowing splint
test for carbon dioxide
when bubbled through lime water it will turn it cloudy
test for carbonates
adding dilute acid, then bubble the gas that is given off through lime water - if it is a carbonate the gas will be carbon dioxide
test for sulphates
using a pipette add a few drops of dilute hydrochloric acid then some barium chloride solution
if a sulphate is present, a white precipitate will form= bariumsulfate
test for halides
to identify a halide ion, add dilute nitric acid then silver nitrate solution
a chloride = white precipitate = silver chloride
a bromide - cream precipitate = silver bromide
a iodide = yellow precipitate = silver iodide
lithium
crimson flame
sodium
yellow flame
potassium
lilac flame
calcium
orange red flame
copper
green flame
Metals with sodium hydroxide
calcium = white
Copper = blue
Iron II = Green
Iron III = Brown
Aluminium = white (dissolves in excess - colourless)