Why is pentanol more soluble in water than pentane?
Select one:
a. Pentane is more flexible, allowing it to better fit in between water molecules
b. Pentanol is a nonpolar molecule, while pentane is a polar molecule. Since pentanol and water have different molecular properties, pentanol dissolves in water
e. Pentanol is nonpolar like water and therefore will dissolve in water.
d. Pentanol and pentane have the same solubility in water.
e. Pentanol is a polar molecule while pentane is non polar. Pentanol and water then have similar properties meaning pentanol will dissolve in water.
The Correct Answer and Explanation is :
The correct answer is:
e. Pentanol is a polar molecule while pentane is nonpolar. Pentanol and water then have similar properties meaning pentanol will dissolve in water.
Explanation:
Solubility is influenced by the principle “like dissolves like,” which means that polar substances tend to dissolve well in other polar substances, while nonpolar substances tend to dissolve well in other nonpolar substances. This principle can help explain why pentanol is more soluble in water than pentane.
Pentanol vs. Pentane:
- Pentanol (C₅H₁₁OH) is an alcohol that contains a hydroxyl group (-OH). This functional group is polar due to the electronegativity difference between oxygen and hydrogen, which creates a partial negative charge on the oxygen and a partial positive charge on the hydrogen. This polarity allows pentanol to form hydrogen bonds with water molecules, making it more soluble in water.
- Pentane (C₅H₁₂), on the other hand, is a nonpolar molecule. It is a hydrocarbon, meaning it only contains carbon and hydrogen atoms. The electronegativity difference between carbon and hydrogen is very small, so pentane does not have significant polarity and cannot form hydrogen bonds with water molecules. As a result, pentane does not dissolve well in water.
Why Pentanol is More Soluble:
Water is a highly polar solvent, and its molecules can form hydrogen bonds with polar molecules like pentanol. This interaction makes pentanol more likely to dissolve in water. In contrast, because pentane is nonpolar, there is little to no interaction between pentane molecules and water molecules, preventing it from dissolving in water.
Thus, the main reason for pentanol’s greater solubility in water is its polarity, which aligns it with water’s properties, enabling better interaction and dissolution.