REPORT Summary: Water Cyclohexane KMnO4 Soluble Insoluble Insoluble Soluble Sucrose Soluble Insoluble Vegetable oil Insoluble Soluble Electrolytes Lightbulb observation for 0.1 M NaCl Lightbulb observation for Sucrose Lightbulb observation for 0.1 M HCl Lightbulb observation for 0.1 acetic acid (HC2H3O2) Lightbulb observation for 0.1 NaOH Lightbulb observation for 0.1 M NH4OH Lightbulb observation for 0.1 ethanol (C2H5OH) Bright glow No light Bright glow Dim glow Bright glow Dim glow No light Concentration: Mass empty evaporating dish (g) Volume NaCl solution (mL) Mass evaporating dish and NaCl solution (g) Mass evaporating dish and dry NaCl (g) 27.503 38.571 29.292 (6 pts) Polarity of Solutes and Solvents Based on the solubility observations, determine if the substance is polar or nonpolar. Table view List view
The Correct Answer and Explanation is:
Correct Answer:
| Substance | Solubility in Water | Solubility in Cyclohexane | Polarity |
|---|---|---|---|
| KMnO₄ | Soluble | Insoluble | Polar |
| Sucrose | Soluble | Insoluble | Polar |
| Vegetable oil | Insoluble | Soluble | Nonpolar |
300-word Explanation (without using the word “we”):
Solubility behavior provides insight into the polarity of a substance. Polar substances tend to dissolve in polar solvents due to similar intermolecular forces, while nonpolar substances dissolve in nonpolar solvents. Water, a polar solvent, supports the dissolution of polar solutes through hydrogen bonding and dipole-dipole interactions. Cyclohexane, a nonpolar solvent, lacks such interactions and instead dissolves nonpolar substances through London dispersion forces.
Potassium permanganate (KMnO₄) dissolves in water but not in cyclohexane. This behavior indicates a polar nature, aligning with its ionic structure, which interacts favorably with water’s polarity. Sucrose, a carbohydrate composed of multiple hydroxyl groups, also dissolves readily in water. These hydroxyl groups form hydrogen bonds with water molecules, further confirming sucrose’s polar nature. Its insolubility in cyclohexane confirms the incompatibility between polar sucrose and nonpolar cyclohexane.
In contrast, vegetable oil dissolves in cyclohexane but remains insoluble in water. This solubility pattern demonstrates a nonpolar character. Vegetable oils consist primarily of long hydrocarbon chains with minimal polar functional groups, allowing effective dispersion in nonpolar environments but little to no interaction with water.
The correlation between solubility and polarity is a key principle in chemistry. “Like dissolves like” serves as a predictive guide: polar substances dissolve in polar solvents, and nonpolar substances dissolve in nonpolar solvents. Observing solubility patterns allows for classification of unknown compounds based on their polarity.
Understanding the polarity of substances helps in predicting reactions, separation techniques, and biological interactions. The solubility results of KMnO₄, sucrose, and vegetable oil in both water and cyclohexane clearly demonstrate the link between solubility and molecular polarity, supporting broader chemical principles involving intermolecular forces and solution behavior.
