Practice predicting whether substances will dissolve based on the rule that polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes.
Read each problem carefully. Use polarity, intermolecular forces, and the idea of like dissolves like to support your answers. Show your work in the space provided.
Using molecular polarity to predict solubility
Chemistry - Grade 9-12
- 1
Water is a polar solvent. Predict whether table salt, sodium chloride, will dissolve well in water. Explain your reasoning.
- 2
Hexane is a nonpolar solvent. Predict whether vegetable oil, which is mostly nonpolar, will dissolve well in hexane. Explain your answer.
- 3
A student mixes iodine, I2, with water and sees very little dissolving. Iodine is nonpolar. Explain why iodine does not dissolve well in water.
- 4
Ethanol has a polar O-H group and a short nonpolar carbon chain. It mixes completely with water. Explain why ethanol is soluble in water.
- 5
Carbon tetrachloride, CCl4, is a nonpolar solvent. Would potassium nitrate, KNO3, dissolve well in carbon tetrachloride? Explain your prediction.
- 6
Rank these solutes from most likely to least likely to dissolve in water: methane, CH4; glucose, C6H12O6; sodium chloride, NaCl. Explain your ranking.
- 7
A nonpolar solvent is used to remove grease from a metal part. Grease is mostly made of long nonpolar hydrocarbon molecules. Explain why the nonpolar solvent is effective.
- 8
A student wants to dissolve sugar in two liquids: water and mineral oil. Sugar molecules contain many O-H groups and are polar. In which liquid should sugar dissolve better? Explain.
- 9
Benzene, C6H6, is nonpolar. Predict whether benzene will dissolve better in water or in hexane. Explain your answer.
- 10
A compound has a polar end and a long nonpolar hydrocarbon tail. Predict whether it might act like soap. Explain how this structure helps it interact with both water and oil.
- 11
Two liquids are mixed. Liquid A is polar, and liquid B is nonpolar. They form two separate layers instead of mixing. Explain why this happens.
- 12
A laboratory technician must choose a solvent to dissolve a polar unknown solid. The choices are water, hexane, and mineral oil. Which solvent is the best first choice, and why?