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Changes in matter


[ Changes in matter ] Importance of chemical reactions ] Chemical Reactions ] On-line practice ]

Two types of changes :

(a)  physical change

  • no new substances formed
  • easily reversed
  • also known as temporary change
  • usually no or little heat taken in or given out
  • example ??

(b)  chemical change

  • new substances formed.  The process that takes place is called chemical reaction.

                         Reactants --> Products

  • difficult to be reversed
  • also known as permanent change
  • heat and /or light energy may be taken in or given out
  • example ??

Most changes in matter occur when an external force acts on it.

Example :

  • heating
  • exposure to light
  • mixing
  • passing an electric current


Changes caused by heating ] Changes caused by light ] Changes caused by mixing ] Changes caused by electricity ]