II. Matter and Energy

II-I. Identify which of the following as a pure substance or a mixture.

• (a) salt, NaCl
  
  pure substance mixture

• (b) air
  
  pure substance mixture

• (c) brass.
  
  pure substance mixture

• (d) H₂O
  
  pure substance mixture

• (e) beer
  
  pure substance mixture

II-2. Identify which of the following pure substances are elements, and which are compounds

• (a) mercury
  
  element compound

• (b) rust, iron oxide
  
  element compound

• (c) aluminum
  
  element compound

• (d) tungsten
  
  element compound

• (e) diamond
  
  element compound

II-3. Identify which of the following mixtures are homogeneous or heterogeneous.

• (a) beef vegetable soup
  
  
  homogeneous mixture heterogeneous mixture

• (b) fog
  
  
  homogeneous mixture heterogeneous mixture

• (c) water and gasoline
  
  
  homogeneous mixture heterogeneous mixture

• (d) sugar dissolved in water
  
  
  homogeneous mixture heterogeneous mixture

• (e) 14 carat gold
  
  
  homogeneous mixture heterogeneous mixture

II-4. Determine whether each of the following properties is physical or chemical.

• (a) A block of styrofoam floats on water.
  
  physical property chemical property

• (b) Sugar becomes caramel when heated above its melting point.
  
  physical property chemical property

• (c) Iron dissolves in hydrochloric acid and hydrogen gas evolves.
  
  physical property chemical property

• (d) Lithium metal has a shiny surface. After exposure to air, it becomes dull.
  
  physical property chemical property

• (e) An iron nail is attracted to a magnet.
  
  physical property chemical property

II-5. Determine whether each of the following is either a chemical change or a physical change.

• (a) pure water from seawater
  
  physical change chemical change

• (b)Electricity is passed through water to produce hydrogen and oxygen gases.
  
  physical change chemical change

• (c) A white T-shirt is dyed red.
  
  physical change chemical change

• (d) A wet mop dries in the sun.
  
  physical change chemical change

• (e) Making ice cube in the freezer.
  
  physical change chemical change

Rosamaría Fong, Instructor of Chemistry,
British Columbia Institute of Technology, Burnaby, B.C. Canada.

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Rosamaría Fong, Instructor of Chemistry
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: Last updated on May 25, 1996