Chemical analysis Flashcards
What is a pure substance?
> A substance that is not mixed with any other substance, which melts at a specific fixed temperature and a fixed boiling point.
What is a formulation?
> A complex mixture that has been designed as a useful product.
What is a chromatography experiment?
> A physical process, which doesn’t involve chemical reactions and no new substances are made
What is the purpose of the chromatography experiment?
> Find out which pens contain 1 colour and which contains a mixture.
Explain the basics of he experiment?
1) We take a special paper called chromatography paper
2)We draw a line with a pencil
3)We put dots of our colour along the line.
4)We place the bottom of the paper into a solvent.
The solvent dissolves the ink in two coloured dots
The paper is the stationary phase
The solvent is the mobile phase.
Explain how to carry out the experiment?
1)Use a ruler to draw horizontal pencil line.
>The line should be around 2cm from the bottom of the paper.
2)Mark 5 pencil spots at equal spaces
3)We use a capillary tube to put the food colours.
4)We pour water into a beaker to a depth of 1cm
5)Attach the paper to a glass rod and put a lid to reduce evaporation
6)Remove the paper when the water has travelled 3/4 up.
How do you workout Rf values?
1)Measure distance from the pencil line to the centre of each spot
2)Then measure the distance moved by the water
What is the formula for Rf value?
Distance moved by solvent.
How do you to test for Hydrogen?
> Remove the Bunge and insert a burning splint
Hydrogen burns rapidly and produces a pop sound
How do you to test for Oxygen?
> We insert a glowing splint
If the splint bursts into flames, its oxygen
How do you to test for Carbon Dioxide?
> We use limewater in an aqueous solution of calcium hydroxide
Draw some of the gas into a pipette
Bubble the gas through the limewater
.If the limewater turns cloudy then Co2 is present
How do you to test for Chlorine?
> We insert damp litmus paper
Chlorine turns the litmus paper into white.
