analysis Flashcards
1
Q
aluminium, calcium and magnesium ions
A
- form white precipitates
- with sodium hydroxide solution
- aluminium hydroxide precipitate dissolves in excess sodium hydroxide solution
2
Q
copper(2) , iron (2) , iron (3)
A
- form blue, green and brown respectively with sodium hydroxide solution
3
Q
carbonates
A
- react with dilute acids to form CO2
- co2 produces a white precipitate with limewater which turns cloudy
4
Q
flame tests
A
lithium - crimson sodium- yellow potasssium - lilac calcium- red barium - green
5
Q
halide ions
A
- in solution produce precipitates with solver nitrate solution in the presence of dilute nitric acid
- sliver chloride is white, silver bromide is cream and silver iodide is yellow
6
Q
sulfate ions
A
- in solution produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid
7
Q
paper chromatography
A
- used to find whether a dye is made up of a single coloured substance or mixture
- soluble dyes spread along the paper faster and so the dyes separate
- base line should be drawn with pencil so that it does not dissolve in the solvent
- the solvent should be below base line to begin with
- a lid should be used to prevemt the solvent from evaporating
- different solvents can be used to maximise separation
8
Q
gas chromatography
A
- allows the separation of a mixture of compounds
- the time taken for a substance to travel through the column can be used to help identify the substance
- the output can be linked to a mass spectrometer, which can be used to identify the substances leaving the end of the column
- the mass spectrometer can also give the molecular mass of each of the substances separated in the column
9
Q
titration
A
- the volumes of acid and alkali solutions that react with eachother can be measured by titration using a suitable indicator
1- wash biurette with water then the solution to be put in it
2- fill the biurette
3- clean a pipette with water and then with the solution that is going to be measured in it
4- transfer 25cm(3) with the pipette into a clean connical flask
5) add a few drops of suitable indicator
6- place a white tile underneath to compare the colour change
7- rough titration
8- repeat - if the concentration of one of the reactants is known the results of the titration can be used to find the concentration of the other reactant
10
Q
titration calculations
A
- calculate number of moles of acid using : n= cv
- work ou the number of moles of alkali using the chemical equation
- calculate the concentration of the alkali using n= cv
c= n/v