A common name for galactose is cerebrose,or brain sugar.What is the molecular formula of galactose if the empirical formula is CH₂O,and the approximate molar mass is 180 g/mol?

Question

Quizplus · Accepted Answer

The empirical formula of CH₂O indicates that galactose contains one carbon atom, two hydrogen atoms, and one oxygen atom. Since the approximate molar mass is 180 g/mol, we can assume that the molecular formula is a multiple of CH₂O. 
To find the molecular formula, we need to calculate the molecular mass of CH₂O:
- Carbon: 1 × 12.01 g/mol = 12.01 g/mol
- Hydrogen: 2 × 1.01 g/mol = 2.02 g/mol
- Oxygen: 1 × 15.99 g/mol = 15.99 g/mol
Total: 30.02 g/mol
Dividing the approximate molar mass by the molecular mass of CH₂O gives us the number of CH₂O units in the molecule:
180 g/mol ÷ 30.02 g/mol ≈ 6
Therefore, the molecular formula is C6H12O6, which corresponds to choice D.

A Common Name for Galactose Is Cerebrose,or Brain Sugar