C 12 Chemical analysis Flashcards
pure substance in chemistry def
made up of only one substance, element or compound
wht are fixed points
melting+boiling points of elements/compounds
characteristics of pure substances boiling points
specific temperatures
mixture
different particles
element
only 1 type of atom
compound
different types of atoms, but all particles are the same
formulation
mixture that has been desgigneted as useful product
examples of formulations
medicines, alloys, fertilisers, food, fuels
(gold alloys for jewellerly)
how is a formulation made
mixing componets in carefully measured quantitiies
purpose of chromatography.
seperate mixtuers and give info that hel to identify substances
how are different dyes separated by paper chromatograhy
solvent moves through paper
different dyes have different solubilities in solvent
and different attractions for the paper
and so are carried different distances
experiment of chromatograhy
draw (pencil) start line on (chromatography) paper
* place spot of food colouring on start line
* use of suitable solvent
* place solvent in beaker / container
* place (chromatography) paper in beaker / container
* so (chromatography) paper is in solvent
* but solvent is below start line
* use a lid
* wait for solvent to travel up the (chromatography) paper (until
near top)
* dry the (chromatography) paper
Measurements
* measure distance between start line and centre of spot
* measure distance between start line and solvent front
* use of measurements to determine Rf value
2 phases of chromatography and examples
stationary phase =paper
mobile phase= solvent
what will a pure sbstance always produce
single spot
Rf formula
distance moved by substance : distance moved by solvent
test for H
burning splint held at end of test tube.
lighted splint ‘pop’
test for O
glowing splint into test tube of gas.
splint relights
test for CO2
limewater turn milky
test for chlorine
damp litumus paper into gas.
paper is bleached + turns white
flame tests
lithium
sodium
potassium
calcium
copper
crimson
yellow
lilac
orange-red
green
reaction with metal hydroxides
al
Mg
Ca
Cu
Fe2
Fe3
precipate colour
white (dissolves in excess)
white
white
blue
green brown
ionic equation for metal hydroxides
Al3+ + 3OH- <– A(OH)3 (s)
Fe2+ +2OH- <–Fe(OH)2 (s)
carbonate test
dilute acid and bubble thrugh limewater
result in fizzing+ limewater milky
carbonate test equation
-
CO2-(inalto)3 + 2H+ <– CO2 +H2O
sulfate test
add dilute hydrochloric acid .
and the barium chloride solution
result white precipitate
sulfate equation
Ba2- + SO2-(alto)4 <– BaSO4
test Halides
Cl
Br
I
add dilute nitric acid, then silver nitrate solution
white precipitate
cream
yellow
equation for halides (x- is the halide)
Ag+ + x- <–Agx (s)
flame emission spectroscopy
used to analyse metal ions in solutions
flame emission spectroscopy process
sample is put into flame and the light given out is passed through a spectroscope.
outout is a line spectrum that will tell us metal ions present and measure concnetrations
