State symbols in Chemical Equations

Learning how to use state symbols in chemical equations is an important step for students looking to succeed in their IB diploma exams. With the right approach, you can easily master the state symbols and make sure your answers clearly represent the reactants, products, and conditions of a chemical reaction. State symbols in Chemical Equations are very key to get marks in IB diploma exams. It is not difficult to use state symbols in chemical equations.

What is state symbols? 

State symbols are symbols used to represent the physical state of reactants and products in a chemical equation.


White solid magnesium Oxide is formed when Magnesium metal ribbon is burned in air( oxygen gas).

2Mg(s) + O2(g)  –> 2 MgO(S) 

Try to write the state symbols of the following equations:

Ag+   + X−   → AgX(s)

Na2O + H2O → 2NaOH

 MgO + H2O → Mg(OH)2

Li2O(s) + 2HCl → 2LiCl  + H2O

MgO + 2HCl  → MgCl2 + H2O

P4O10+ 6 H2O→ 4H3PO4

Hint: Use following points for deciding state symbols.

For acids and ionic compounds you can use aqueous solutions with out much thinking. For most diatomic molecules you can use gas as state symbol if you do not have any idea. In the chemical reactions between halogens and halogen compounds, the halogen molecules like chlorine molecule(Cl2) etc, you should use aqueous as state symbol. for all metals except mercury , use solid as state symbol.

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