c8 - chemical analysis

• chromatography is used to separate mixtures of soluble substances
• Why is the line drawn 2cm from the bottom of the chromatography paper drawn in pencil?

  it is insoluble so will not be drawn up the paper with the solvent
• an impure mixture or substance will produce at least two spots
• rf value = distance travelled by spot / distance travelled by solvent
• a substance is likely to be the same if it produces the same number of spots , and these match in colour
• what phase is the paper?

  stationary
• solvent - the substance in which others are dissolved
• what is the mobile phase?

  the solvent
• chromatography is used to separate different coloured substances in a mixture
• what is a formulation?


  a mixture that has been designed for a specific purpose
• what are some examples of formulations?


  cleaning products, fertilisers, cosmetics, food products , metal alloys
• what is the test for oxygen?

  put a glowing splint into the mouth of the test tube, it will relight if oxygen is present
• what is the test for hydrogen ?


  hold a lit splint in the mouth of the test tube, a 'squeaky pop' will be produced if hydrogen is present
• what is the test for carbon dioxide?

  bible it through limewater, it will turn cloudy if carbon dioxide is present
• what is the test for chlorine?


  hold against damp blue litmus paper, it will bleach if chlorine is present
• in chromatography, a substance will move more if it's attracted to the mobile phase. it won't move if it's attracted to the stationary phase
• a substance will move further up paper if it is more soluble (attracted to mobile phase)
• a pure substance is a single element or compound
• you can find out if a substance is put by finding out its boiling point. it will be 100 ℃ if it is pure