Chemical Reactions and Equations PDF

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 (i) Initial 1 (in Fe)...

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 (i) Initial 1 (in Fe) 3 (in Fe3O4) (ii) To balance 1×3 3 To equalise Fe, we take three atoms of Fe on the LHS. 3 Fe + 4 H2O → Fe3O4 + 4 H2 (1.8) Step VI: Finally, to check the correctness of the balanced equation, we count atoms of each element on both sides of the equation. (1.9) 3Fe + 4H2O → Fe3O4 + 4H2 (balanced equation) The numbers of atoms of elements on both sides of Eq. (1.9) are equal. This equation is now balanced. This method of balancing chemical equations is called hit-and-trial method as we make trials to balance the equation by using the smallest whole number coefficient. Step VII: Writing Symbols of Physical States Carefully examine the above balanced Eq. (1.9). 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. (1.9) becomes 3Fe(s) + 4H2O(g) → Fe3O4(s) + 4H2(g) (1.10) Note that the symbol (g) is used with H2O 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 – 340 atm (1.11) CO(g) + 2H2 (g)  → CH3 OH(l) Sunlight 6CO2 (aq) + 12H2O(l)  Chlorophyll → C6 H12O 6 (aq) + 6O2 (aq) + 6H2 O(l) (1.12) (Glucose) Using these steps, can you balance Eq. (1.2) given in the text earlier? Chemical Reactions and Equations 5 2024-25