C8- chemical analysis

what is a pure substance

something that only contains one compound or element

how can you tell the purity of a substance

measuring its melting and boiling point and comparing it with a pure substance - the closer it is the more pure

what is a formulation

formulations are useful mixtures with a precise purpose that are made by following a ‘formula’. each component is measured in quantity so that it meets its required function

where can formulations be found in everyday life

cleaning products,cosmetics, fertilisers, food and drink

2 phases of paper chromatography

• mobile phase

• stationary phase

what is the R_f value and how is it calculated

the ratio between the distance travelled by the dissolved substance and the solvent

R_f = distance travelled by substance / distance travelled by solvent (water line)

chlorine test

it bleaches damp litmus paper, turning it from purple to white.

oxygen test

put a glowing splint inside a test tube containing oxygen, the oxygen will relight the glowing splint

carbon dioxide test

bubbling carbon dioxide through limewater causes the solution to turn cloudy

test for hydrogen

if you hold a lit splint at the open end of a test tube containing hydrogen you get a squeaky pop