Purity, Formulations and Chromatography

• what is a pure substance


  A single element or compound, not mixed with any other substance
• how can melting and boiling points be used to test if a substance is pure


  Pure substances have a specific melting and boiling point.

  If a substance is not pure, it will melt over a range of temperatures.
• what are formulations


  mixtures designed for a specific purpose
• examples of formulations


  paints, medicines, cleaning agents
• how are formulations made


  by mixing specific amounts of different chemicals to get certain properties
• What is chromotography used for?


  To separate mixtures and help identify substances
• what is the stationary phase in chromotography


  chromotography paper
• what is the mobile phase in chromotography


  solvent
• what does the distance the chemical moves up each paper dependent on


  how soluble the chemical is in the solvent

  
  

  more soluble = further
• how do you calculate rf value


  Distance travelled by substance / distance travelled by solvent
• how do you test for hydrogen


  Squeaky pop test
• how do you test for oxygen


  Relights a glowing splint
• how do you test for carbon dioxide


  Limewater goes cloudy
• how do you test for chlorine

  Bleaches damp litmus paper