05 Chemical Bonds
06 Acids, Bases and Salts
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6.4.3 Writing Ionic Equation of The Reaction of Acids and Alkalies

Writing Ionic Equation of the Reactions of Acids

Steps in writing the ionic equation of the reactions of acids:

  1. Write the chemical equation of the reaction.
  2. List down all the ion presence below the equation.
  3. Cancel the ions that do not change in the reaction.
  4. Rewrite the equation with only the ions that have changed in the reaction.
 
Example

Write the ionic equations for the following reactions:
a. Acids + Zinc
b. Acids + Metal Carbonate
c. Acids + Base Oxide
d. Acids + Alkali

Answer:
a. Acids + Zinc
We can use any acid for the reaction, as it will not affect the ionic equation at the end.
In this case, let’s use hydrochloric acid for the chemical equation.

Step 1: Writing the Chemical Equation
   2HCl + Zn → ZnCl2 + H2
Step 2: List down the ions
   2H+ + 2C l + Zn → Zn2+ + 2C l + H2
Step 3: Cancel the ions that do not change
   2H+ + 2C l + Zn → Zn2+ + 2C l + H2
Step 4: Rewrithe the equation
   2H+ + Zn → Zn2+ + H2

b. Acids + Metal Carbonate

Let’s use hydrochloric acid and calcium carbonate
Step 1:
   2HCl + CaCO3 → CaCl2 + CO2 + H2 O
Step 2:
   2H+ + 2C l + Ca2+ +CO32− → Ca2+ + 2C l + CO2 + H2O
Step 3:
   2H+ + 2C l + Ca2+ +CO32− → Ca2+ + 2C l + CO2 + H2O
Step 4:
   2H+ +CO32− →CO2 + H2O

c. Acids + Base Oxide
Let’s use Hydrochloric acid and Zinc Oxide
Step 1:
   2HCl + ZnO → ZnCl2 + H2O 
Step 2:
   2H+ +2C l − + Zn2+ + O2− → Zn2+ + 2C l− + H2O 
Step 3:
   2H+ + 2C l + Zn2+ + O2− → Zn2+ + 2C l + H2
Step 4:
   2H+ + O2− → H2


d. Acids + Alkali
Step 1:
   HCl + NaOH → NaCl + H2
Step 2:
   H+ + C l +Na+ + OH → Na+ + C l + H2
Step 3:
   H+ + C l + N a+ + OH− → Na + + C l + H2
Step 4:
   H+ + OH → H2O