ch6-chemical analysis Flashcards
whatre mixtures
2 or more elements that ARENT chemically combined
whatre the 4 physical ways of seperating mixtures
1-filtration
2-crystalisation
3-distilation
4-chromotography
whatre the 2 types of distilation
fractional and simple
whatre the differences between fractional and simple distilation
they both use a condenser (surrounded by cool water) but simple is used to seperate solid from liquid while fractional is used to seperate 2 liquids with different boiling points
when is filtration used
to seperate insoluble solids from a liquid
when is crystalisation used
to seperate a soluble solid from a liquid by heating the liquid which evaportaes away from the solid thats colleted at the beaker
why is paper chromotography used
to identify pure substances from mixtures and analyse unkknown substances in solutions
descrube the method of paper chromotography
1- draw a starting line in pencil (cause it wont dissolve) on the bottom of the paper
2-place 2 dots woth different colors
3-place paper in solvent
4-pure substances will produce 1 dot while mixtures will produce more than 1
5-calculate rf value
what happens in paper chromotography if a substance is more soluble
itll move farther up the paper and be in mobile phase for longer
what is in stationary phase and whats in mobile phase
mobile- solvent since its continuesly moving
stationary-paper since it doesnt move
how do we calculate rf values from chromorography
distance traveled by substance/distance traveled by solvent
why do we use rf values
to identify different substances thatre matched against databases
what are the characteristics of ammonia
sharp chocking smell
whats the positive test for ammonia
damp red litimus paper turns blue and white smoke of ammonium chloride when near hydrogen chloride gas (from hcl)
whats type of white smoke is released when ammonia is held near hyrodgen chlorine gas (from hcl)
ammonium chlride smoke
whats the test for hydrogen
lighted splint pops
whats the test for oxygen
glowing splint relights
whats the test fir chlorine
damp red litimus paper turns blue then white
whats the test for carbon dixode
lime water(calcium hydroxide)turns cloudy
what 3 metals form white precipitates when reacted with sodium hydroxide
calcium aluminium and magnesium
whatre the 2 ways to test for metal positive ions
flame tests and sodium hydroxide precipitate test
what colour precipitate is formed when iron (3) ions react with sodium hydroxide
brown
what colour precipitate is formed when copper ions react with sodium hydroxide
blue
what colour precipitate is formed when iron (2) ions react with sodium hydroxide
green
what metal white precipitate dissolves in sodium hydroxide
aluminium
what 5 metal ions can be tested using flames
lithium
sodium
potassium
calcium
barium
what flame colour is a positive lithium ion
crimson
what flame colour is a positive sodium ion
yellow
what flame colour is a positive potassium ion
lilac
what flame colour is a positive calcium ion
red
what flame colour is a positive barium ion
green
how do we test for carbonates
1- add dilue acid
2-acid will react w carbonate to produce co2 and it will fizz
3-carbon dioxide gas should turn limewater cloudy
what are the 3 halide ions we can test for
bromide chloride and iodide
how do we idenitfy halide ions
first add nitric acid then silver nitrate solution then diff halide will form diff coloured precipitates
whats color is the silver nitrate precipitate of chloride
white
whats color is the silver nitrate precipitate of bromide
cream
whats color is the silver nitrate precipitate of iodide
yellow
what 2 substances do you add to identify sulfates
add hydrochloric acid then barium chloride
what precipitate di sulfates form
white barium sulfate precipitate
