Chemical Reactions and Equations Lecture Notes

Practice flashcards covering types of chemical reactions, oxidation-reduction, corrosion, rancidity, and chemical vs. physical changes based on the lecture notes.

Exothermic Reaction

A reaction in which heat is evolved, such as the reaction of $CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq)$ or the decomposition of vegetable matter into compost.

Endothermic Reaction

A reaction in which heat is absorbed, including thermal, electrolytic, and photochemical decomposition.

Thermal decomposition

A type of decomposition reaction triggered by heat, exemplified by $CaCO_3(s) \xrightarrow{\Delta} CaO(s) + CO_2(g)$.

Electrolytic decomposition

A type of decomposition reaction involving electricity, such as $2H_2O(l) \xrightarrow{Electricity} 2H_2(g) + O_2(g)$.

Photochemical decomposition

A type of decomposition reaction occurring in the presence of light, such as $2AgCl(s) \xrightarrow{Sunlight} 2Ag(s) + Cl_2(g)$.

Oxidation

A chemical process defined by the addition of oxygen, the removal of hydrogen, or the loss of electron(s).

Reduction

A chemical process defined by the removal of oxygen, the addition of hydrogen, or the gain of electron(s).

Corrosion

A natural slow process in which metal reacts with surroundings like $O_2$ and $H_2O$ and gets wasted.

Silver sulphide

The black coating formed on silver as a result of corrosion.

Basic copper carbonate

The green coating formed on copper as a result of corrosion.

Rust

The reddish brown coating formed on iron, represented by the formula $Fe_2O_3 \cdot H_2O$.

Rancidity

The spoilage of food caused by factors such as oxygen, light, high temperature, metal, and bacteria.

BHA

An antioxidant used to prevent rancidity, known as Butylated hydro anisole.

BHT

An antioxidant used to prevent rancidity, known as Butylated hydro toulene.

Physical Change

A change where no new substances are formed, such as melting, boiling, sublimation, or cutting of paper/wood.

Chemical Change

A change where new substances are formed, generally accompanied by changes in colour, pH, evolution of gas, temperature changes, or formation of a precipitate.

Quick lime

The common name for the chemical compound $CaO$.

Slaked lime

The common name for the chemical compound $Ca(OH)_2$.

Limestone

The common name for the chemical compound $CaCO_3$.

Lead iodide ($PbI_2$)

A yellow precipitate formed when lead nitrate reacts with potassium iodide.

Nitrogen dioxide ($NO_2$)

A gas produced during the decomposition of lead nitrate that is characterized by brown fumes.

Combination Reaction

A type of reaction where two or more reactants combine to form a single product, such as $C(s) + O_2(g) \rightarrow CO_2(g)$.

Displacement Reaction

A reaction where a more reactive element displaces a less reactive element from its compound, such as $Fe(s) + CuSO_4(aq) \rightarrow FeSO_4(aq) + Cu(s)$.

Double Displacement Reaction

A reaction where there is an exchange of ions between the reactants, such as $Na_2SO_4(aq) + BaCl_2(aq) \rightarrow Ba(SO)_4(s) + 2NaCl(aq)$, which is also a precipitation reaction.

Inert gas (e.g., $N_2$)

A substance used in packaging to prevent rancidity by displacing oxygen.