Physical & Chemical Changes

  Physical Change Chemical Change
  • No new substance is produced
  • Substance remains the same even with a change of state
  • May require addition of energy
  •  Release of energy may occur
  • Final substance is substantially different than initial substance
  • New substance is always produced
  • Energy is usually released but may be required to get the change going
  • Outside may look different
  • Inside remains the same
  • Particles may be rearranged
  • Forces of attraction between particles may be weaker or stronger
  • A new substance is produced
  • The particles of the new substance do not resemble those of the old substance
  • Internally, the substance produced is different than the old substances
  • Mixing sugar and water
  • Ice melts into water
  • Solid wax  ==>    Liquid wax
  • Vinegar and baking soda mix to form carbon dioxide
  • Hydrochloric acid reacts with magnesium metal to form hydrogen gas


Chemical Properties:                

Properties of a substance observed when and how it interacts with other substances

Examples of Chemical Properties

  • iron rusts in moist air (with the oxygen in the air), but gold does not

  • hydrogen burns in oxygen, but nitrogen does not (they are both gases that make-up air)

  •  zinc reacts with acid, but glass does not

Activity: Give three reasons why fireworks are examples of chemical changes

A.    Physical Properties:

Properties that can be observed without changing the substance into another substance

Intrinsic Physical Properties: Properties that do no change with amount of substance

  1. State at room temperature   
  2. Density
  3. Colour             
  4. Luster
  5. Electrical Conductivity  
  6. Melting Point
  7. Odour  
  8. Boiling Point
  9. Solubility in water   
  10. Attraction to/by magnets
Extrinsic Physical Properties: Properties that change without the amount of substance     
  1. Mass
  2. Shape              
  3. Texture
B.    Chemical Properties:

Illustrate how a substance reacts or fails to react with other substances to produce new substances

Example:    Sodium fizzes vigorously in water, silver tarnishes and dynamite explodes.

  1. Flammability (does it burn easy?)
  2. Ease of oxidations (does it rust or corrode rapidly?)
  3. Reaction with acid or base
  4. Heat of combustion
  5. Does the substance support combustion
  6. Does the substance decompose on heating

C.    Physical Reaction:

  1. Alters only the form or state of a substance
  2. Does not change the chemical composition
Look at the following images and list all the Physical Properties and Chemial Properties you can think of.
  1.  ice at room temperature
  2.  rock crushing
  3.  liquid water
  4.  clouds