Question

Play a game for writing formula.

Example 2: A low-cost model for writing formulae: Take empty blister packs of medicines. Cut them in groups according to the valency of the element, as shown in the figure. Now, you can make formulae by fixing one type of ion into other.

For example:

The formula for sodium sulphate:

2 sodium ions can be fixed on one sulphate ion.

Hence, the formula will be Na₂SO₄.

Do it yourself:

Now, write the formula of sodium phosphate.

Answer 1

Objective: Create the correct chemical formula for sodium phosphate using a low-cost model.

Instructions:

1. Step 1: Prepare blister packs
   • Take empty blister packs from medicines and cut them into groups. Each group should represent the valency of an element.
   • For example, cut one group of blister packs to represent sodium ions (Na⁺) and another group to represent phosphate ions (PO₄³⁻).
2. Step 2: Identify the valencies
   • Sodium (Na): Valency = +1
   • Phosphate (PO₄): Valency = -3
3. Step 3: Fix the ions together
   • To balance the charges, you will need 3 sodium ions (Na⁺) to balance the -3 charge of one phosphate ion (PO₄³⁻).
   • Therefore, 3 blister packs representing sodium ions will be fixed to 1 blister pack representing a phosphate ion.
4. Step 4: Write the chemical formula
   • Since 3 sodium ions (Na⁺) are needed to balance the 1 phosphate ion (PO₄³⁻), the formula for sodium phosphate will be:

Na₃PO₄

Explanation:

In this low-cost model, the blister packs represent ions, and you align them according to their valencies. By using 3 sodium ions (blister packs) to match with 1 phosphate ion, the correct formula is formed. This method makes the concept of balancing chemical equations more interactive and engaging.