qualitative analysis Flashcards
flame test lithium
red
flame test sodium
yellow
flame test potassium
lilac
flame test calcium
orange-red
flame test copper
blue-green
test for carbon dioxide
bubbling through limewater (turns cloudy)
why must the test for any ion be unique?
so you can determine which ion is present without confusion, if the test is not specific, another test would be required to determine the ion
carbonate ion test
two centimetres of the solution being tested
add a few drops of dilute hydrochloric acid
testing for sulphate ions
two centimetres of the solution being tested
add a few drops of dilute hydrochloric acid and shake
add a few drops of barium chloride
halide ion test
two centimetres of the solution being tested
add a few drops of dilute nitric acid and shake
add a few drops of silver nitrate
carbonate ion positive test
bubbling occurs
sulphate ion positive test
white precipitate forms
chloride ion halide test positive result
white precipitate forms
bromide ion halide test positive result
cream precipitate forms
iodide ion halide test positive result
yellow precipitate forms
cation precipitate test
two centimetres of the solution being tested
add a few drops of sodium hydroxide and shake
observe precipitate formed (if white complete next step)
fill the tube about halfway with sodium hydroxide
copper precipitate test
blue
iron (II) precipitate test
green
iron (III) precipitate test
brown
calcium precipitate test
white (stays the same/remains cloudy when excess sodium hydroxide is added)
aluminium precipitate test
white (turns colourless when excess sodium hydroxide is added)
ammonium ion test
two centimetres of the solution being tested
add a few drops of dilute sodium hydroxide
warm the mixture
hold damp red litmus paper over the test tube
ammonium ion positive result
litmus paper turns blue
chlorine gas test
hold damp blue litmus paper over the mouth of the test tube which is filled with the gas being tested
chlorine gas positive result
litmus paper turns red
ammonia gas test
hold damp red litmus paper over the mouth of the test tube which is filled with the gas being tested
ammonia gas positive result
red litmus paper turns blue
oxygen gas test
test tube filled with the gas being tested
get a glowing split and hold it inside the test tube
oxygen gas positive result
the glowing splint combusts and relights
hydrogen gas test
test tube filled with the gas being tested
hold a lit splint over the mouth of the test tube
hydrogen gas positive test
squeaky pop noise
test for water
using anhydrous copper (II) sulphate which is originally white solid
add the substance being tested for water
water positive test result
turns blue
test for water purity
pure water should boil at 100 degrees
water impurity positive result
water boils at a temperature higher or lower than 100 degrees
what do instrumental methods of analysis improve?
sensitivity, accuracy and speed of tests
which methods improve speed, accuracy and sensitivity of tests?
instrumental methods
carbonate ionic equation
CO3^2- (aq) + 2H^+ (aq) –> CO2 (g) + H2O (l)
sulphate ionic equation
Ba^2+ (aq) + SO4^2- (aq) –> BaSO4 (s)
halide ionic equation
Ag+ (aq) + X- (aq) –> AgX (s)
where X = Cl^-, Br^- or I^-
uses of a flame photometer
measures light intensity so you can find the concentration of ions using a calibration curve) in a dilute solution and make an emission spectra
also identify metal ions by comparing the data with reference data
