# Types Of Chemical Reactions **URL:** \ **Category:** Science\ **Created:** [June 7, 2020, 3:48pm UTC](https://howtodiscuss.com/t/types-of-chemical-reactions/488 "2020-06-07T15:48:34Z")\ **Posts on this page:** 1\ **Showing post:** 2
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**Types of chemical reactions** The most important types of chemical reactions are: 1. Combination or Synthetic reaction 2. Decomposition reaction 3. Single replacement reactions 4. Double replacement reactions 5. Neutralisation 6. Hydrolysis 7. Exothermic Reactions 8. Endothermic Reaction **Definition of chemical reaction** “Change in the nature and composition of a substance as a result of combination or separation of atoms or molecules is known as chemical reaction.” Or “Changes occur in the nature of a substances with the composition or decomposition of the substances is called a chemical reaction.” **Chemical changes** Some of the changes around us are purely physical. When water boils, for example, the liquid water turns into gaseous steam. In winter water freezes to form ice. These are physical changes in which chemical composition of water (H2O) does not change. On the other hand, if we pass an electric current through water, a mixture of gases are produced. We cannot turn these gases back into liquids. The molecules that make up these gases are no longer molecules. They are mixture of hydrogen (H2) and oxygen (O2). If a small flash of fire is applied to the mixture, it explodes as the gases recombine to produce water. Both of these are chemical changes. **Types of chemical reactions** The most important types of chemical reactions: **1. Synthetic Reaction** In this type of reaction, two or more elements generally unite to form a single compound. Elements may combine with elements or they may combine with compounds. Compounds may also unites with other compounds. **2. Decomposition Reaction** In this type of reaction, a compound is broken down into simpler compounds or into it’s elements. **3. Single Replacement Reactions** In this type of reaction, a chemically more active elements reacts with a compound to replace a less active element in that compound. As a result of this reaction, a new element or a new compound is formed. **4. Double Replacement Reactions** Sometimes two compounds react chemically to form new compounds. This reaction occurs when elements in these compounds exchange places with each other. **5. Neutralisation** Neutralisation is an example of double replacement reactions in which two reactants are acid and base which form salt and water. During this reaction, hydrogen ion or proton from the acid is neutralised by the hydroxide ion from the base to form water molecule (H2O). **6. Hydrolysis** Hydrolysis is also an example of double decomposition reaction in which one of the reactant is water. When the hydrogen ion and hydroxide ion of water molecule combine with the ions of weak acids or weak bases to give basic or acidic solution, then hydrolyzation of salts take place and the process is known as hydrolysis. **7. Exothermic Reactions** An exothermic reaction is that in which heat is evolved. Or simply the reaction which release heat or other forms of energy. When hydrochloric acid (HCl) and sodium hydroxide are mixed they react to form water and sodium chloride with release of heat energy. **9. Endothermic Reaction** An endothermic reaction is that which requires continuous source of energy, usually heat to keep it going. Decomposition of water into oxygen and hydrogen is an endothermic reaction. Formation of ‘red oxide’ of ‘lead’ after heating of ‘lead’ is also an endothermic reaction. --- _[View the full topic](https://howtodiscuss.com/t/types-of-chemical-reactions/488)._