Chemical analysis Flashcards
What is a pure substance?
It is 1 type of element or compound.
Melt and boil at one temp
What is a formulation and give an example?
mixtures that have been carefully designed to have specific properties
EG cleaning agents, paints ,medicine
Many formulations have complex mixtures in which each chemical has its own purpose
What is chromatography?
separates mixtures into their constituent component
The solvent dissolves and carries them up the paper
can be used to identify artificial colours
What is the gas test for hydrogen and oxygen?
HYDROGEN-mixed with air burns with a squeaky pop
OXYGEN-relights a glowing splint
What is the procedure for the instrumental method?
1) A sample of metal solution is placed in a flame and the light emitted is passed through a spectroscope
2) Producing a line through spectrum which can be used to identify metal ions in the solution and measure the conc of the metal ions in the solutions
What is an impure substance?
It is a mixture.
They do not boil and melt at one temp they change state over a range of temp
What is the Rf equation?
Rf= distance moved by substance/distance by solvent
What is the difference between station phase and mobile phase?
Stationary phase is when it does not move mobile phase is when it moves
What colour does indicator paper turn in the chlorine test/What solution is produced in the carbon dioxide gas test?
CHLORINE-turns damp indicator paper white
CARBON DIOXIDE-when bubbled through lime water a solution of calcium hydroxide turns the lime water cloudy
What is the instrumental method?
Flame emission spectroscopy is used to analyse solutions that contain metal ions
What alloy do you but in the Bunsen burner flame/what acid is used in this experiment?
Piece of nichrome wire in a Bunsen flame and then dip it in concentrated hydrochloric acid to clean it
What do you do after dipping it in the hydrochloric acid?
Dip the wire in a compound and put it in the flame to see what colour it produces
What colour shows copper & calcium ion is present/If the colour crimson red is shown which ion is present
GREEN-CU
BRICK RED-CA
lithium-crimson red
If the colour lilac and yellow is shown what ions are present?
lilac-potassium
yellow-sodium
What do carbonates react with/what do they produce give example?
React with dilute acid to form carbon dioxide
Calcium carbonate + hydrochloric acid— calcium chloride + carbon dioxide + water
What does carbon dioxide to do lime water/Are most metal carbonates soluble or insoluble?
Turn lime water cloudy (milky)
insoluble
What three metals forms a white precipitate when mixed with sodium hydroxide solution?
Aluminium-dissolves if more sodium hydroxide solution is added
CA,MG does not dissolve in excess sodium hydroxide
calcium
magnesium
When copper reacts with sodium hydroxide what precipitate is formed?
dark Blue
What is the difference between iron (11) and iron (111) when mixed with sodium hydroxide solution?
iron 11 forms green precipitate
iron 111 forms brown precipitate
What do you need for a white precipitate of barium sulfate to be produced?
dilute hydrochloric acid + barium chloride solution and a solution that contains sulfate ions
What do halide ions react with?
silver nitrate solution and dilute nitric acid to form silver halide precipitate
What colour precipitation does silver chloride, bromide and iodide produce?
chloride-white
bromide-cream
iodide-yellow
