Question

There is 40 % C, 67% H2, find the empirical formula

Hint:

For empirical formula calculations, always convert mass percentages to moles and find the simplest whole-number ratio.

Answer 1

Step 1: Understand the given percentages.
The given composition is 40% carbon and 67% hydrogen. These percentages represent the mass of each element in the compound.
Step 2: Convert percentages to moles.
To find the empirical formula, we first convert the percentages to moles. The molar masses of carbon and hydrogen are approximately 12 g/mol and 1 g/mol, respectively. \[ \text{Moles of C} = \frac{40}{12} = 3.33 \, \text{mol} \] \[ \text{Moles of H} = \frac{67}{1} = 67 \, \text{mol} \]
Step 3: Find the mole ratio.
Now, divide each mole value by the smaller value to find the ratio of elements: \[ \frac{3.33}{3.33} = 1 \quad \text{and} \quad \frac{67}{3.33} \approx 20 \] The mole ratio is 1:20 for C:H.
Step 4: Write the empirical formula.
The empirical formula for this compound is CH\(_{20}\).