Chemical Equations- Balancing Of Chemical Equations

A chemical equation is a shorthand method of using chemical formulae to present a chemical or physical change. Substances combining or disappearing are called reactants, while those that are newly formed or appearing are called products. In a chemical reaction, the reactants are written first on the left followed by an arrow pointing to the products written on the right-hand side of the arrow.

REACTANTS  → PRODUCTS

Balanced Chemical Equations

Some of the basic requirements needed for a balanced chemical equation include the following:

• The chemical equation must be a statement of experimental fact and not a guess
• The chemical formulae of reactants and products must be written as they occur naturally, e.g diatomic gases, such as hydrogen, nitrogen, oxygen, chlorine, and iodine.
• The physical state of all chemical substances must be indicated for example, a solid is denoted by (s), a pure liquid is denoted by (l), an aqueous solution is denoted by (aq) and a gas is denoted by (g).

The following steps must be followed to obtain a balanced equation:

• State the experimental facts
• Write the reactants and products in words to conform to experimental facts
  • The plus sign(+) between the reactants may be reacts with, combines with, or mixes with.
  • The plus sign between the products may mean and together with
• Write the formula of the reactants and products from the word equation as they occur in nature. Once a formula is written correctly, the coefficients, written as subscripts should not be altered.
• The equation is balanced by making the number of atoms of each element on the left to be equal to the number of atoms of each element on the right. Once a chemical reaction is balanced, the law of conservation of matter is obeyed.

Example

Hydrogen gas burns in oxygen gas to produce water. This is a statement of experimental fact.

Word Equation

Hydrogen + Oxygen → Water

Formula Equation

H_2(g) +O_(2)(g) → H₂O_l (Not balanced)

By inspection, there are two hydrogen atoms on the left of the arrow and two on the right; the equation is balanced with respect to hydrogen however, there are two oxygen atoms on the left and one on the right. To balance it on the right, 2 is written before H₂O to give:

H₂ +O₍₂₎ → 2H₂O(Not balanced)

Four hydrogen atoms are now on the right, while two are on the left. To balance it on the left, 2 is written before H₂:

2H_2(g) +O_(2)(g) → 2H₂O_l

If you try to balance the equation using the mole concept also, you would get the same result.

Use Of Fractions To Balance Chemical Equations

Another way one can balance Chemical equations is via the use of fractions and not that the use of fractions is usually not advised especially when balancing chemical equations.

Lithium Metal burns in Chloringe gas to give Lithium Chloride i.e

Li_(s) + Cl_2(g) → LiCl_(s)

The equation is balanced with respect to Lithium and to balance Cl atom, write 1/2 before Cl₂ to obtain:

Li + 1/2Cl₂₎ → LiCl (Balanced)

It is not possible to obtain one-half molecule of Chlorine hence, we multiply through by 2 to clear the fraction

2Li + Cl₂ → 2LiCl (Balanced)