chemical analysis Flashcards
What does a pure substance contain?
only one type of element or one type of compound
What happens to pure substances
- They melt and solidify at one temperature
- They boil and condense at one temperature
What is a substance?
It is a substance which has nothing added to it
What are impure substances?
They are mixtures. Which do not melt and boil at one temperature
What are Formulations?
They are mixtures that have been carefully designed to have a specific property
Give examples of formulations.
E.g. fuels, cleaning agents, paints, medicines
What does chromatography involve?
- a stationary phase which does not move
- a mobile phase which does move
What happens in paper chromatography
- The stationary phase is the absorbent
- The mobile phase is the solvent (e.g. water)
What is the role of chromatography?
It is used to identify artificial colours by comparing them to the results obtained from known substances
What is the Rf value equal to?
Distance moved by substance/ distance moved by solvent
What is the test for hydrogen?
When mixed with air, it burns with a squeaky pop
What are the properties for hydrogen?
A colourless gas
Combines violently with oxygen when ignited
What is the test for chlorine gas?
Turns damp indicator paper white
What are the properties of chlorine?
A green poisonous gas that bleaches dyes
What is the test for oxygen
Relights a glowing splint
