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

📘 Empirical Formula Calculation

Step 1: Assume 100 g of the compound

Since the percentages are given, assume that the compound has a mass of 100 g.

Carbon = 40 g
Hydrogen = 6.67 g
Oxygen = 53.33 g

Step 2: Convert masses into moles

Use:

Moles = Given Mass ÷ Atomic Mass

Step 3: Calculate moles of each element

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

🎬 Mole Conversion Animation

C H O → Moles

Mass of each element is converted into moles using its atomic mass.

Step 4: Divide all mole values by the smallest value

The smallest number of moles is approximately:

3.33

Now divide each mole value by 3.33.

C = 3.33 ÷ 3.33 = 1

H = 6.67 ÷ 3.33 ≈ 2

O = 3.33 ÷ 3.33 = 1

Step 5: Obtain the simplest whole-number ratio

C : H : O = 1 : 2 : 1

Therefore, the simplest ratio of the atoms is:

1 : 2 : 1

🎬 Empirical Formula Formation

C H₂ O → CH₂O

The simplest whole-number ratio gives the empirical formula.

✅ Final Answer

C : H : O = 1 : 2 : 1

Empirical Formula = CH₂O

🎯 Quick Method

1. Assume 100 g compound.

2. Convert percentage into grams.

3. Divide each mass by atomic mass.

4. Divide all mole values by the smallest value.

5. Convert into the simplest whole-number ratio.

Percentage → Mass → Moles → Ratio → Empirical Formula