Physical change


Physical change
A physical change is a change in which no new substances are formed and most physical changes are reversible. Examples: changes of shape, changes of states, passing electricity through a copper wire. Special details which do not change in a substance without new substances being formed are called physical properties. e.g. change of water into ice or water vapor, change of density.
"Compare:" Chemical change - A chemical change (chemical reaction) is a change in which one or more new substances are formed and the change can not be reversed. Burning of wood is a chemical change as new substances (e.g. carbon dioxide, water vapour) are formed and you cannot change them back. Other examples: burning of a candle, rusting of iron. Special details that describe how a chemical change takes place are called chemical properties.
Chemical change can be exposure of light (photosynthesis), passing electric current through (electrolysis) including to burn material (combustion). Furthermore, chemical change can be oxidation (oxygen combine with material) or mixing (material mixing together)(e.g. react with acid, react with alkalis (base))


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