Question

How to write chemical reaction

Answer 1

Step by step guide to writing a chemical equation for a chemical reaction

• Write down a word equation for the chemical reaction
• Write down the unbalanced equation using correct chemical symbols for all the reactants and products
• Balance the equation by inspection. (Ensure that the same number of each type of atom appears on both sides of the equation)
• Write the state symbol after each chemical symbol

Tips for balancing the equation


​​​​​​● Typically, you balance H (hydrogen) atoms first, followed by O (oxygen) atoms, then any other atoms. OR you can start by balancing the most complicated molecule.

• Never change the chemical symbol of a substance. (Do not change the coefficient in the chemical symbols of reactants or products)
• A number in front of a formula multiplies every symbol that follows it.

Example:

Formation of iron(III) chloride from the reacting iron with chlorine gas

• Iron + chlorine
  →
  →
  iron(III) chloride
• Before balancing:
  Fe+
  Cl
  2
  →
  FeCl
  3
  Fe+Cl2→FeCl3
• Balance number of Cl atoms: There are 2 Cl atoms on the left and 3 Cl atoms on the right. The simplest way to balance Cl atoms is to multiply 3 on the left and 2 on the right to make a total of 6 Cl atoms.
• We obtain:
  Fe+3
  Cl
  2
  →2
  FeCl
  3
  Fe+3Cl2→2FeCl3
  .
• Notice that the number of Fe atoms are not the same for both side: 1 on the left and 2 on the right. Hence, we will just have to multiply 2 on the left.
• We have:
  2Fe+3
  Cl
  2
  →2
  FeCl
  3
  2Fe+3Cl2→2FeCl3
• Not forgetting to include the state symbols:
  2Fe(s)+3
  Cl
  2
  (g)→2
  FeCl
  3
  (s)
  2Fe(s)+3Cl2(g)→2FeCl3(s)