how to change the state of the substance during chemical reaction
Answers
Explanation:
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. Although we call them physical "reactions," no reaction is actually occurring. In order for a reaction to take place, there must be a change in the elemental composition of the substance in question.
The change of state is likewise a physical change. In this scenario, one can observe a number of physical properties changing, such as viscosity and shape. As ice turns into water, it does not retain a solid shape and now becomes a viscous fluid. The physical "reaction" for the change of ice into liquid water is:
H2O(s)→H2O(l)
The following are the changes of state:
Solid → Liquid (Melting)
Liquid → Gas (Vaporization)
Liquid → Solid (Freezing )
Gas → Liquid (Condensation)
Solid → Gas (Sublimation)
If heat is added to a substance, such as in melting, vaporization, and sublimation, the process is endothermic. In this instance, heat is increasing the speed of the molecules causing them move faster.
If heat is removed from a substance, such as in freezing and condensation, then process is exothermic. In this instance, heat is decreasing the speed of the molecules causing them move slower.