Topic 8 Flashcards
Define…
Pigment
Solvent
Binder
Additives
Gives colour
Used to dissolve other components and alter viscosity
Forms a film that holds the pigment in place
Added to further change the physical and chemical properties
How do you test for…
Chlorine?
Oxygen?
Carbon dioxide?
Hydrogen?
Bleaches damp litmus paper
Relights a glowing splint
Bubbles
Turns limewater cloudy
A burning splint pops with a squeak
What is a carbonate?
How do you test for carbonates?
Contains CO3 2- ions
Use a dropping pipette to add a few drops of dilute acid
Connect test tube to one containing limewater
If carbonate ions are present the limewater will bubble and go cloudy
What is a sulphate ion?
How do you test for sulphates?
SO4 2- ions
Use a dropping pipette to add dilute hydrochloric acid followed by barium chloride solution
If sulphate ions are present a white precipitate of barium sulphate will form
How do you test for halides?
What colour precipitates do they form?
Add a couple drops of dilute nitric acid followed by a couple of drops of silver nitrate solution
Fluoride = colourless Chloride = white Bromide = cream Iodide = yellow
How do you do a flame test?
What colour flame do these have? Lithium Calcium Sodium Copper Potassium
Clean a nichrome wire loop by holding it in a blue flame
Dip the loop into dilute acid
Hold it under a flame
Dip loop in sample you want to test and put it back in the flame
Record the colour
Crimson Orange red Yellow Green blue Lilac
How do you identify insoluble metal hydroxides?
What colours are.. Calcium Copper (II) Iron (II) Iron (III) Aluminium Magnesium
Add a few drops of sodium hydroxide solution into your unknown solution
White Blue Green Brown White at first but redissolves in excess NaOH to form a colourless solution White
How does flame emission spectroscopy work?
Sample is placed in a flame
As ions heat up the electrons gain energy and move to higher shells
When electrons drop down again they release energy as light
Light passes through a spectroscope which detects different wavelengths to produce a line spectrum
As no two ions have the same charge and electron arrangement different ions emit different wavelengths and have different line spectrum
The intensity of the spectrum indicates the concentration of the ion in solution
What are the advantages to using instruments in spectroscopy?
Very sensitive so can detect tiny amounts of substances
Very fast
Very accurate
