Topic 8: Chemical Analysis

• What is a chromatogram?

  A graph showing separation results
• What is chromatography used for?

  To separate mixtures based on distribution
• What does flame emission spectroscopy analyze?

  Metal ions in solutions
• How is a flame test conducted?

  By inserting a wire loop into a flame
• What is a formulation?

  A designed mixture for a useful product
• What defines an impure substance?

  Made of two or more unbonded elements
• What are instrumental methods used for?

  To detect and identify elements and compounds
• What does litmus paper indicate?

  Acidity or alkalinity of a substance
• What is the mobile phase in chromatography?

  The phase where molecules can move
• What is precipitation in chemistry?

  The creation of a solid from a solution
• What is a pure substance in chemistry?

  A single element or compound only
• What does the Rf value represent?

  The ratio of distances moved by compounds
• What is the stationary phase in chromatography?

  The phase where molecules are stationary
• What is a pure substance?

  A single element or compound
• How do pure substances behave when heated?

  They melt and boil at specific temperatures
• How can melting and boiling points be used?

  To distinguish pure substances from mixtures
• What does 'pure substance' mean in everyday language?

  A substance that is unadulterated and natural
• Give an example of a pure substance.

  Pure milk
• What is a formulation?

  A mixture designed as a useful product
• Why are formulations considered complex mixtures?

  Each chemical has a particular purpose
• How are formulations created?

  By mixing components in measured quantities
• Name some examples of formulations.

  Fuels, cleaning agents, paints, medicines
• What is chromatography used for?

  To separate mixtures and identify substances
• What are the two phases involved in chromatography?

  The stationary phase and the mobile phase
• What does separation in chromatography depend on?

  The distribution of substances between phases
• What is the formula for Rf value?

  Rf value = distance moved by substance ÷ distance moved by solvent
• How do different compounds behave in chromatography?

  They have different Rf values in different solvents
• What happens to a pure compound in chromatography?

  It produces a single spot in all solvents
• What is paper chromatography?

  A technique separating compounds by speed in solvent
• How does solubility affect movement in paper chromatography?

  The more soluble, the further it travels up
• What does chromatography separate in colored substances?

  Different pigments
• What is a pigment?

  A solid, colored substance
• What sound does hydrogen make when tested?

  'Squeaky pop'
• How is hydrogen tested in a laboratory?

  By using a burning splint in the gas
• What happens to a glowing splint in oxygen?

  It relights
• How is oxygen tested in a laboratory?

  By inserting a glowing splint into the gas
• What is the test for carbon dioxide?

  Bubble gas through limewater
• What indicates the presence of carbon dioxide in limewater?

  It turns milky
• What is the test for chlorine gas?

  Use damp litmus paper
• What happens to damp litmus paper in chlorine gas?

  It bleaches and turns white