Review Questions

1
Review Questions

• Molasses is warmed it becomes less viscous
• P no new substance created, still molasses.
• Chair is painted it has a new colour
• P no new substance, chair is colour of paint.
• Sugar is stirred into hot water it dissovles
• P no new substance, sugar and water still
  present in a solution.

2

• Wood is sawed some of it changes to sawdust.
• P change in form, still wood.
• Wood is burned, ashes remain.
• C change in colour (brown to black), heat and
  light produced in fire.
• Vinegar added to baking soda, bubbles seen.
• C formation of new gas.

3

• When a sample of blue crystals is heated, a
  vapour is given off and a white powder remains.
• P or C?
• Chemical Change new gas created (vapour),
  colour change from blue to white.

4

• 12. Physical change the substance returned to
  the original substance as it cooled. Therefore
  it went through a change of state which is a
  physical change.
• Density would allow you to distinguish iron
  pyrite from real gold. You would have to measure
  the mass of the rock using a scale. You would
  then measure the volume of the rock using
  displacement or an appropriate formula. Once
  completed, use the formula d m/v and solve for
  density. If the density is 19.3 g/mL the rock is
  gold. If it is not, it is not real gold.

5

• All density problems should be solved using the
  formula
• dm/v vm/d mdxv
• Show all work, answer in a therefore statement,
  make sure units are correct.

6

• p. 205
• 11. Pots and pans must be good conductors of
  heat. Heat must pass easily through the pan to
  cook the food.
• They must be malleable so that they can be
  hammered into a particular shape without
  breaking.

7

• p. 204 13
• Temperature is not a characteristic physical
  property because it is not unique to the
  substance. Temperature of the substance will
  depend on its surroundings or what is happening
  to the substance. It cannot be used to identify
  a substance. A characteristic physical property
  is unique to a substance. For example, melting
  point, boiling point and density are unique and
  can be used to identify a substance.
  

8

• Solid mixture Pizza (mechanical)
• Steel (Alloy/solution)
• Liquid mixture
• Pop (Mechanical mixture)
• Saltwater (Solution)
• Gaseous mixture
• Air

9

• Copper would float in liquid mercury because its
  density is less than Mercurys density.
• Carbon fibres density is much less than
  aluminum, therefore when used in bicycles it
  makes the bike lighter allowing the cyclist to
  move faster.

10

• A dented table tennis ball can be repaired by
  placing it in a cup of hot water. Use the p. t.
  to explain how this is possible.
• Particles of air in tennis ball.
• Hot water causes particles to move faster.
• Particles collide more often and with more force,
  pushing each other away further.
• The increase in pressure on the dent forces the
  dent outwards and repairs the ball.

11

• 28. bbq fuel physical property
• Vapourizes from liquid to gas, moves easily into
  barbeque.
• Chemical property
• combustible (reacts with oxygen to form heat and
  light) in order to cook food.