Question

hi ............ mates

please argent


Chapter 1 chemical reaction and equations

explain all reactions

Answer 1

4 Fe(s) + 3O2 ?2Fe2O3 (rust). Iron Oxygen Ferric oxide

Combustion :  

AB + O2 ? Oxide of A & B.

Combination :  

A + B ? C

Decomposition :  

AB ? A + B

Displacement :  

A + BC (aq) ? AC (aq) + B

Double Displacement :  

AB (aq) + CD (aq) ? AD (aq) + CB

�   Precipitation reaction: An insoluble solid known as precipitate is formed during a double displacement reaction. Such reactions are also known as precipitation reactions.

�   Redox reaction: A reaction in which oxidation and reduction take place simultaneously in a reaction, is known as a redox reaction.

�   Oxidation is a chemical process in which a substance gains oxygen or loses hydrogen.

�   Reduction is a chemical process in which a substance gains hydrogen or loses oxygen.

�   If a substance gains oxygen or loses hydrogen during a reaction, it is said to be oxidised.

�   If a substance gains hydrogen or loses oxygen during a reaction, it is said to be reduced.

�   A substance that loses oxygen or gains hydrogen is known as an oxidising agent.

�   A substance that loses hydrogen or gains oxygen is known as a reducing agent.

�   An oxidising agent gets reduced whereas a reducing agent gets oxidised.

�   In terms of electronic concept, Oxidation is defined as a loss of electrons while reduction is defined as a gain of electrons.

�   Corrosion is the slow eating up of metals by the action of air and moisture on their surfaces. Corrosion in case of Iron is known as Rusting.

�   Chemically, rust is hydrated ferric oxide (Fe2O3.xH2O)

�   Advantages of corrosion: Though corrosion is undesirable, it can be advantageous in case of aluminium which on exposure to air, gets coated with a protective layer of aluminium oxide. This protects the metal nderneath from further corrosion and damage.

�   Rancidity: When oils and fats or foods containing oils and fats are exposed to air, they get oxidised due to which the food becomes stale and gives a bad aste or smell. This is called Rancidity.

�   Rancidity can be prevented by: a Adding antioxidants i.e. the substances which prevent oxidation b Refrigeration c Storing the food in air-tight containers

Answer 2

combination reaction means when a single product is formed from two or more reactants
decomposition reaction means when a single reactant breaks down to form simpler products
Precipitate reaction means any reaction that produces a precipitate
Double Displacement reaction means when a reactions in which there is an exchange of ions between the reactions