Questions: Question 18 of 20 The empirical formula of a compound is CH2O. It has a molar mass of 180 g/mol. Which of the following represents its molecular formula? A C3H6O3 B C2H4O2 C C6H12O6 D C5H10OO5 E CHO

Solution Steps

The empirical formula given is \(\mathrm{CH}_{2}\mathrm{O}\). To find its molar mass, we calculate the sum of the atomic masses of each element in the formula:

• Carbon (C): \(12.01 \, \text{g/mol}\)
• Hydrogen (H): \(1.008 \, \text{g/mol} \times 2 = 2.016 \, \text{g/mol}\)
• Oxygen (O): \(16.00 \, \text{g/mol}\)

Adding these together gives the molar mass of the empirical formula:

\[ 12.01 + 2.016 + 16.00 = 30.026 \, \text{g/mol} \]

The molar mass of the compound is given as \(180 \, \text{g/mol}\). We need to find how many times the empirical formula fits into the molecular formula by dividing the molar mass of the compound by the molar mass of the empirical formula:

\[ \frac{180 \, \text{g/mol}}{30.026 \, \text{g/mol}} \approx 6 \]

Since the ratio is approximately 6, the molecular formula is 6 times the empirical formula. Therefore, we multiply each subscript in \(\mathrm{CH}_{2}\mathrm{O}\) by 6:

• Carbon: \(1 \times 6 = 6\)
• Hydrogen: \(2 \times 6 = 12\)
• Oxygen: \(1 \times 6 = 6\)

Thus, the molecular formula is \(\mathrm{C}_{6}\mathrm{H}_{12}\mathrm{O}_{6}\).

Final Answer