of Physical States Writing Symbols of Physical States Carefully examine the above balanced Eq. ( . ). Does this equation tell us anything about the physical state of each reactant and product?
No information has been given in this equation about their physical states. To make a chemical equation more informative, the physical states of the reactants and products are mentioned along with their chemical formulae. The gaseous, liquid, aqueous and solid states of reactants and products are represented by the notations (g), (l), (aq) and (s), respectively. The word aqueous (aq) is written if the reactant or product is present as a solution in water.
The balanced Eq. ( . ) becomes 3Fe(s) + 4H O(g) → Fe O (s) + 4H (g) ( . ) Note that the symbol (g) is used with H O to indicate that in this reaction water is used in the form of steam.
Usually physical states are not included in a chemical equation unless it is necessary to specify them. Sometimes the reaction conditions, such as temperature, pressure, catalyst, etc., for the reaction are indicated above and/or below the arrow in the equation. For example – CO(g) + 2H (g) 340atm CH OH(l) ( . ) 6CO (aq) 12H O(l) C H O (aq) 6O Sunlight Chlorophyll (aq) 6H O(l) ( .
) (Glucose) Using these steps, can you balance Eq. ( . ) given in the text earlier? Step V: Examine the above equation and pick up the third element which is not balanced.
You find that only one element is left to be balanced, that is, iron. Atoms of In reactants In products iron Initial (in Fe) (in Fe O ) To balance × ( . ) (balanced equation)