What are Physical Changes ??

By Oscar C

The definition and Some examples

Physical changes are changes affecting the form of a chemical substance, but not its chemical composition


Here are some examples



  • Ice melting involves a change from a solid to a liquid and the substances maintain the properties of water because the molecules never change.
  • Water boiling is a physical change as water molecules vibrate faster, they enter the gas phase and become water vapor.
  • Hot molten iron is a liquid and when left to cool will from solid steel and can take many forms.
  • Dissolving sugar in water is a physical change. The solid sugar never loses its properties, the molecules become separated by water and the sugar can easily be recovered by evaporating the water
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People Also Ask These Questions


  1. What is the difference between a physical change and a chemical change?
  2. Is evaporation of water a physical or chemical change?
  3. Is ice melting a physical or chemical change?
  4. What are the changes in matter?

Answers

  1. The difference between a physical reaction and a chemical reaction is composition. In a chemical reaction, there is a change in the composition of the substances in question; in a physical change there is a difference in the appearance, smell, or simple display of a sample of matter without a change in composition.
  2. Physical Change in Water. Water as steam or water vapor. It is formed when water is heated to the boiling point or it evaporates. Water as a liquid is formed then water vapor is cooled or ice is heated
  3. When you melt an ice cube (H2O), you have a physical change because you add energy. In this example, you added enough energy to create a phase change from solid to liquid. Physical actions, such as changing temperature or pressure, can cause physical changes. No chemical changes took place when you melted the ice.
  4. Changes of state are physical changes in matter. They are reversible changes that do not involve changes in matter's chemical makeup or chemical properties. Common changes of state include melting, freezing, sublimation, deposition, condensation, and vaporization.
Chemical and Physical Changes