Chemical Reactions and Equations

Comprehensive vocabulary flashcards covering key terms, concepts, reaction classifications, chemical tests, and everyday oxidation effects from Class 10 Chemistry Chapter 1.

Chemical Reaction

A process in which one or more substances undergo a transformation to produce new substances with different chemical properties through the making and breaking of bonds between atoms.

Reactants

The starting substances that undergo a chemical transformation during a reaction, conventionally written on the left-hand side ($\text{LHS}$) of a chemical equation.

Products

The new substances formed as a result of a chemical reaction, written on the right-hand side ($\text{RHS}$) of a chemical equation.

Chemical Equation

A concise representation of a chemical reaction using chemical formulas, symbols, and physical state notations of the substances involved.

Skeletal Chemical Equation

An unbalanced chemical equation in which the total number of atoms of each element on the reactant side is not equal to that on the product side, such as $\text{Mg} + \text{O}_2 \rightarrow \text{MgO}$.

Balanced Chemical Equation

A chemical equation in which the total number of atoms of each element is equal on both the reactant and product sides, satisfying the law of conservation of mass.

Law of Conservation of Mass

The fundamental scientific principle stating that mass can neither be created nor destroyed in a chemical reaction; the total mass of the reactants must equal the total mass of the products.

Hit-and-Trial Method

A procedure for balancing chemical equations by trying the smallest whole-number coefficients before chemical formulas without altering compound subscripts.

Aqueous Solution ($(aq)$)

A state notation denoting that a reactant or product is dissolved in water as a solvent in a chemical reaction.

Combination Reaction

A chemical reaction in which two or more substances (elements or compounds) combine to form a single product, generalized as $A + B \rightarrow AB$.

Quick Lime

The common name for calcium oxide ($\text{CaO}$), an oxide of a group $2$ element used in the manufacture of cement and in whitewashing.

Slaked Lime

The common name for calcium hydroxide ($\text{Ca(OH)}_2$), formed when calcium oxide reacts vigorously with water; its dilute aqueous solution is termed lime water.

Slaking of Lime

The vigorous, highly exothermic reaction between solid calcium oxide ($\text{CaO}$) and water to produce calcium hydroxide ($\text{Ca(OH)}_2$) and release large quantities of heat.

Exothermic Reaction

A chemical reaction that releases heat energy to the surroundings along with the formation of products, such as natural gas combustion and respiration.

Endothermic Reaction

A chemical reaction in which energy is absorbed from the surroundings in the form of heat, light, or electricity, such as photosynthesis and thermal decomposition.

Decomposition Reaction

A chemical reaction in which a single reactant breaks down into two or more simpler products when supplied with energy.

Thermal Decomposition

A decomposition reaction initiated and driven by the absorption of heat energy, such as heating limestone ($\text{CaCO}_3$) to produce quick lime ($\text{CaO}$) and carbon dioxide ($\text{CO}_2$).

Electrolytic Decomposition

A decomposition reaction carried out by passing an electric current through an electrolyte, such as the electrolysis of water producing hydrogen and oxygen in a $2:1$ volume ratio.

Photolytic Decomposition

A decomposition reaction initiated by the absorption of light energy, such as the decomposition of white silver chloride ($\text{AgCl}$) or silver bromide ($\text{AgBr}$) into silver and halogen gas.

Displacement Reaction

A chemical reaction in which a more reactive element displaces a less reactive element from its compound in aqueous solution, represented as $A + BC \rightarrow AC + B$.

Reactivity Series

A series of metals arranged in order of decreasing chemical reactivity: $\text{K} > \text{Na} > \text{Ca} > \text{Mg} > \text{Al} > \text{Zn} > \text{Fe} > \text{Pb} > [\text{H}] > \text{Cu} > \text{Hg} > \text{Ag} > \text{Au}$.

Double Displacement Reaction

A chemical reaction in which there is an exchange of ions (cations and anions) between two reacting compounds to form two new compounds, represented as $AB + CD \rightarrow AD + CB$.

Precipitate

An insoluble solid substance that separates and settles out of a liquid solution during or after the completion of a chemical reaction.

Precipitation Reaction

Any chemical reaction between two soluble solutions that produces an insoluble salt (precipitate).

Oxidation

A chemical process involving the gain of oxygen, the loss of hydrogen, or the loss of electrons by a substance.

Reduction

A chemical process involving the loss of oxygen, the gain of hydrogen, or the gain of electrons by a substance.

Redox Reaction

A chemical reaction in which oxidation and reduction take place simultaneously, with one substance being oxidized while another is reduced.

Oxidising Agent

A substance that causes oxidation in another substance by accepting electrons or supplying oxygen, and is itself reduced during the reaction.

Reducing Agent

A substance that causes reduction in another substance by donating electrons or supplying hydrogen, and is itself oxidized during the reaction.

Corrosion

The gradual destruction and deterioration of metals caused by chemical reactions with atmospheric substances such as moisture, oxygen, and acids.

Rusting

The specific oxidation process occurring when iron reacts with oxygen and water to form a reddish-brown flaky substance consisting of hydrated iron(III) oxide.

Rancidity

The condition produced by the aerial oxidation of fats and oils in foods, characterized by an unpleasant taste and odor.

Antioxidants

Chemical substances added to foods containing fats and oils to inhibit oxidation and prevent rancidity.

Catalyst

A substance that increases the rate of a chemical reaction or lowers the temperature and pressure required to initiate it, without being consumed in the process.

Thermite Reaction

A highly exothermic single-displacement reaction between iron(III) oxide ($\text{Fe}_2\text{O}_3$) and aluminium ($\text{Al}$) producing molten iron and aluminium oxide ($\text{Al}_2\text{O}_3$).

Hydrogen Pop Test

A characteristic test for hydrogen gas ($\text{H}_2$) in which bringing a burning candle or splint to the mouth of the test tube produces an explosive popping sound.

Lime Water Test

A diagnostic test for carbon dioxide gas ($\text{CO}_2$) in which the gas is bubbled through aqueous calcium hydroxide, turning the solution milky due to insoluble calcium carbonate formation.