Chapter 19, Problem 51A

Interpretation Introduction

Interpretation:

The balancing of redox reactions in acidic and basic medium are to be compared

Concept introduction:

Acidic medium involve presence of hydrogen ion and basic medium involves presence of hydroxyl ions. Thus in both medium, charges are balanced using hydrogen ion and hydroxyl ions.

Answer to Problem 51A

In acidic medium, after balancing the number of atoms, hydrogen ions are added on one side to balance the charges on both sides.

In basic medium, after balancing the number of atoms, hydroxy ions are added on one side to balance the charges on both sides.

Explanation of Solution

Half reaction method to balance ionic equation in acidic solution involve:-

• Assign the oxidation number to each element.
• Check which element is oxidized and which element is reduced. Write oxidation and reduction half reactions.
• Check the change in oxidation number for the elements which are oxidized and reduced.
• Then add enough hydrogen ions and water molecules to the equation to balance hydrogen atoms on both sides.
• Adjust the coefficients so that number of electrons lost in oxidation is equal to electrons gained in reduction.
• Add the balanced half reactions.

Half reaction method to balance ionic equation in basic solution involve:-

• Assign the oxidation number to each element.
• Check which element is oxidized and which element is reduced. Write oxidation and reduction half reactions.
• Check the change in oxidation number for the elements which are oxidized and reduced.
• Then add enough hydroxl ions and water molecules to the equation to balance hydrogen atoms on both sides.
• Adjust the coefficients so that number of electrons lost in oxidation is equal to electrons gained in reduction.
• Add the balanced half reactions.

Conclusion

Thus medium changes the method to balance the equations.