NCERT Class 10 Science Chapter 1: Chemical Reactions and Equations

Vocabulary flashcards covering key chemical reaction types, definitions, and specific chemical phenomena from NCERT Class 10 Science Chapter 1.

Magnesium Oxide ($MgO$) layer

A very stable compound formed when magnesium metal reacts with atmospheric oxygen; it must be removed by cleaning the magnesium ribbon before burning to allow the reaction with oxygen to proceed.

Balanced Chemical Equation

A chemical equation in which the number of different atoms on both the reactant and product sides are equal, ensuring the reaction obeys the Law of Conservation of energy.

Quick Lime

Also known as Calcium Oxide ($CaO$), this substance is used for whitewashing and reacts with water according to the equation: $CaO + H_2O \rightarrow Ca(OH)_2$.

Electrolysis of Water

The process where water ($H_2O$) is hydrolyzed to release $H_2$ and $O_2$ gas; the volume of Hydrogen collected is double that of Oxygen because two molecules of Hydrogen are released for every one molecule of Oxygen.

Displacement Reaction

A chemical reaction in which a more reactive metal displaces a less reactive metal from its oxide or salt solution.

Double Displacement Reaction

A reaction characterized by a mutual exchange of ions between two compounds, such as the reaction between Silver nitrate ($AgNO_3$) and Sodium chloride ($NaCl$) to form Silver chloride and Sodium nitrate.

Oxidation (in terms of Oxygen)

A chemical process where oxygen is added to an element or substance, such as the reaction $4Na(s) + O_2(g) \rightarrow 2Na_2O(s)$.

Reduction (in terms of Oxygen)

A chemical process where oxygen is removed from a compound, such as the reaction $CuO(s) + H_2(g) \rightarrow Cu(s) + H_2O(l)$.

Combination Reaction

A reaction where two or more molecules react together to form a single larger molecule.

Decomposition Reaction

The process of splitting a larger molecule into two or more smaller molecules; it is considered the opposite of a combination reaction and is typically endothermic.

Exothermic Reaction

A reaction in which energy is released from the system into the surroundings, such as explosions, concrete setting, or nuclear fission.

Endothermic Reaction

A reaction where energy is absorbed from the surroundings in the form of heat, such as photosynthesis or the melting of ice.

Respiration

An exothermic process where food molecules like glucose are broken down in the presence of oxygen to form carbon dioxide, water, and energy ($C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{Energy}$).

Thermal Decomposition (Thermolysis)

A decomposition reaction where energy is supplied specifically in the form of heat, such as the decomposition of potassium chlorate into potassium chloride and oxygen.

Electrolytic Decomposition (Electrolysis)

A decomposition reaction where energy is supplied in the form of electricity, such as passing electricity through molten sodium chloride.

Photodecomposition Reaction (Photolysis)

A decomposition reaction where energy is supplied in the form of light, such as the decomposition of hydrogen peroxide into water and oxygen.

Precipitation Reaction

A double displacement reaction occurring in aqueous solutions where one of the formed compounds is an insoluble solid (precipitate) that settles at the bottom.

Copper Oxide ($CuO$)

A black-colored compound formed when the shiny brown element Copper ($Cu$) is heated in air and reacts with atmospheric oxygen.

Rusting

A form of corrosion where iron reacts with atmospheric oxygen and moisture to form Iron(III) oxide; it can be prevented by applying paint to isolate the metal surface.

Rancidity

An unpleasant change in the taste and smell of food containing oils and fats caused by aerial oxidation; it is prevented by flushing food packets with unreactive Nitrogen gas.

Corrosion

A process where a refined metal is gradually degraded as it is oxidized by atmospheric oxygen to form more stable compounds like oxides.