Question: 143: A dehydration reaction links two glucose molecules to product maltose. If the formula for glucose is \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6} then what is the formula of maltose?
(1) \mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}
(2) \mathrm{C}_{12} \mathrm{H}_{24} \mathrm{O}_{11}
(3) \mathrm{C}_{12} \mathrm{H}_{20} \mathrm{O}_{10}
(4) \mathrm{C}_{12} \mathrm{H}_{24} \mathrm{O}_{12}
Answer: Option (1)
Explanation:
Maltose is a disaccharide formed by the condensation of two glucose molecules.
Each glucose molecule has the formula \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}.
When two glucose molecules combine, their total formula becomes
\mathrm{C}_{12} \mathrm{H}_{24} \mathrm{O}_{12}.
During a dehydration reaction, one molecule of water is removed.
The formula of water removed is \mathrm{H}_{2} \mathrm{O}.
After removing water, the final formula becomes
\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}.
Therefore, the molecular formula of maltose is
\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}.