C12 - Chemical Analysis Flashcards
What is a pure substance
A pure substance is one that is made up of only one substance. It can either be an element or a compound
Examples of pure substances
- Distilled water
- Helium
- Pure ethanol
What is special about a pure substances melting and boiling points?
They are fixed and exact
What do impurities do to a substance?
They generally lower the melting point and raise the boiling
How can you identify an impure substance?
They don’t have a set melting/ boiling point; they melt/boil over a range
What is a formulation
A formulation is a mixture that has been designed to give a useful product
Examples of formulations
- Medicinal drugs
- Paint
- Washing up liquid
- Cosmetics
- Fertilisers
What are the two different phases in chromatography
- The mobile phase (solvent)
- The stationary phase (usually paper )
What does a high affinity to the mobile phase do
The substance moves further up
What does a high affinity to the stationary phase do
The substance doesn’t move up as far
How to calculate the Rf (retention factor)
Distance moved by substance / distance moved by solvent
Test for hydrogen
Lightened splint will make a squeaky pop with hydrogen
Test for oxygen
- Use hydrogen peroxide to make oxygen
- Glowing splint will be relit
Test for carbon dioxide
Limewater does cloudy due to carbonate precipitate forming
Test for chlorine
Damp blue litmus paper will turn white (get bleached)