A compound contains 40% carbon, 6.67% hydrogen and 53.33% oxygen. Calculate its empirical formula.

📘 Step-by-Step Solution

Step 1: Assume 100 g of the Compound

Since percentages are given, assume that the total mass of the compound is 100 g.

Carbon = 40 g

Hydrogen = 6.67 g

Oxygen = 53.33 g

Step 2: Calculate the Number of Moles

Use the formula:

Number of moles = Given mass ÷ Atomic mass

Element	Mass	Atomic Mass	Moles
C	40 g	12	40 ÷ 12 = 3.33
H	6.67 g	1	6.67 ÷ 1 = 6.67
O	53.33 g	16	53.33 ÷ 16 = 3.33

Step 3: Find the Simplest Ratio

Divide all the mole values by the smallest value, which is approximately 3.33.

C = 3.33 ÷ 3.33 = 1

H = 6.67 ÷ 3.33 ≈ 2

O = 3.33 ÷ 3.33 = 1

C : H : O

1 : 2 : 1

🎬 Empirical Formula Animation

C H H O

C : H : O = 1 : 2 : 1 → CH₂O

The simplest whole-number ratio gives the empirical formula.

Step 4: Write the Empirical Formula

The simplest ratio of C, H and O is:

C : H : O = 1 : 2 : 1

Therefore, the empirical formula is:

CH₂O

✅ Final Answer

Empirical Formula = CH₂O

Thus, the empirical formula of the compound is CH₂O.

🎯 Quick Revision

% → Assume 100 g
Mass → Moles
Moles → Divide by Smallest
Simplest Ratio → Empirical Formula

40% C, 6.67% H, 53.33% O → CH₂O