Equations, Mixtures and Chromatography

• What does a chemical formula show in a compound?

  The proportion of elements in a compound
• What does a chemical equation represent?

  The overall change in a reaction
• What are the reactants in a chemical reaction?

  The starting substances in a reaction
• What are the products in a chemical reaction?

  The substances formed in a reaction
• What is the word equation for the combustion of methane?

  Methane + Oxygen → Carbon Dioxide + Water
• What is the symbol equation for the combustion of methane?

  $CH_4 +$$2O_2 → CO_2 +$$2H_2O$
• Why must a chemical equation be balanced?

  To have the same number of each atom
• What do the large numbers in front of formulas indicate?

  How many units of that substance there are
• What is a mixture?

  • Substances made of different elements or compounds
  • Not chemically bonded to each other
  • Example: Air is a mixture
• How do mixtures affect the chemical properties of substances?

  The properties remain unchanged in mixtures
• How can mixtures be separated?

  By physical methods without chemical reactions
• What is the process of paper chromatography?

  1. Spot of mixture placed on filter paper
  2. Pencil line drawn for solvent level
  3. Paper removed when solvent nears top
  4. Components separate as they move up
  5. Insoluble components stay on baseline
• What is the purpose of the pencil line in paper chromatography?

  To indicate the starting level of solvent
• What happens to soluble components in paper chromatography?

  They move up the paper with the solvent
• What is a chromatogram?

  The result of a chromatography experiment
• What is the role of the solvent in paper chromatography?

  To carry the components up the paper