Chemical Reactions and Equations

Vocabulary and key concepts from the lecture on chemical equations, balancing, and conservation of mass.

Chemical equation

A representation of a chemical reaction that uses chemical formulae instead of words to be more concise and useful.

Word-equation

A description of a chemical reaction using the names of the substances involved, such as $Magnesium + Oxygen \rightarrow Magnesium\,oxide$.

Reactants

The substances that undergo chemical change in a reaction, written on the left-hand side ($LHS$) of a chemical equation.

Products

The new substances formed during a reaction, written on the right-hand side ($RHS$) of a chemical equation.

Skeletal chemical equation

A chemical equation that is unbalanced because the mass is not the same on both sides, meaning the number of atoms of each element is not equal on the $LHS$ and $RHS$.

Law of conservation of mass

A principle from Class IX stating that mass can neither be created nor destroyed in a chemical reaction; the total mass of the elements in the products must equal the total mass of the elements in the reactants.

Balanced chemical equation

A chemical equation in which the number of atoms of each element remains the same before and after a chemical reaction, appearing equally on both sides of the arrow.

Zinc and Sulphuric acid reaction

A reaction represented by the balanced equation $Zn + H_2SO_4 \rightarrow ZnSO_4 + H_2$, where the number of atoms for $Zn$, $H$, $S$, and $O$ are identical on both sides.

Burning of magnesium in air

A reaction represented by the skeletal equation $Mg + O_2 \rightarrow MgO$.

Iron and water reaction (Eq. 1.4)

A skeletal chemical equation represented as $Fe + H_2O \rightarrow Fe_3O_4 + H_2$.