There are two types of changes :-

  • Chemical changes – Chemical changes occur by chemical reactions . These changes produce heat and some of them need heat for the reaction to take place. During chemical reactions, atoms of the substance get rearranged and a change in energy is experienced as new products are made. 
  • Physical changes – These are the changes which do not affect the chemical composition of a substance but the form of a substance. These changes are usually used for separating two components of a mixture but it does not separate a compound chemically bonded together. It mainly affects the size, shape etc. 

Examples of both changes 

Chemical change

Hydrogen and sodium hydroxide is produced as a result of a chemical reaction between sodium and water. Due to the high amounts of energy produced by the reaction the hydrogen gas produced as a product burns away in the air. 

Physical change

A mixture of salt and water completely dissolves the salt with water but it can be separated by getting the water evaporated. This is mainly possible because physical changes only make the substances undergo a change in their form. In the physical change chemical composition states completely intact. 

Types of chemical changes 

The types of chemical changes are as follows :-

  • Inorganic changes – Inorganic chemistry is the branch of chemistry which deals with those reactions which don’t include carbon. Inorganic changes are mainly performed in laboratories and in some industries. Neutralization is the chemical change which mixes an acid with a base which results in the formation of water and salt. Other examples of chemical changes are oxidation, combustion, redox etc. 
  • Organic changes – Organic chemistry is the branch of chemistry which deals with carbon and all the elements which tend to react with it. The output of these changes are mainly mineral oils and products manufactured in pharmaceuticals, paints, cosmetics etc. Gasoline is created by cracking hydrocarbons in an oil refinery. This is obtained from crude oil and is done because of the high demand of fuel than heavy hydrocarbons. Examples of chemical changes are methylation, condensation reactions, polymerisation etc. 
  • Biochemical changes – Biochemistry is a subject which looks into different chemical changes taking place in living organisms. It involves moderation of enzymes and hormones or bodily processes. Photosynthesis is the process of carbon dioxide and water getting changed in oxygen and sugars. This occurs in living plants and it occurs in the presence of sunlight. Protein synthesis and Krebs cycle are some other examples of chemical changes. 

The conditions of a chemical change 

The conditions of a chemical change which serve as an evidence of the reaction are :- 

  • Odour – Due to the chemical reactions occurring during the chemical changes some of the cases show some change in the smell /odour of the outputs than the original substances. 
  •  Colour – The outputs of the reactions may vary in colour from the initial elements of the reaction. 
  • Temperature – Due to the chemical changes being of two types, exothermic and endothermic different levels of temperature and energy production are seen. 
  • Composition – Chemical changes result in the products which are different than the initial substances chemically. 
  • Heat – Some chemical changes take place along with giving away light and heat at times. 
  • Gases – As a by product of the chemical changes many types of gases can be released during or after the reaction. They might even occur as bubbles on top of a liquid during reaction. 
  • Precipitate – Precipitate is the leftover solid formation which is formed after the process of precipitation. 
  • Decomposition – Chemical changes sometimes result into the decomposition of organic matter . Rotting of food is one such example. 
  • Type of change – These changes are always irreversible and can only be changed by other chemical reactions. 

Conclusion 

Chemical and physical changes both occur side by side in nature and some are done by humans to achieve the desired results they want. All the reactions have some limitations that need to be followed for these changes to actually occur.