Study guides › C/P › General Chemistry
Solutions & Colligative Properties
Solutions run through the whole MCAT, from IV fluids to precipitation. You will convert between concentration units, apply solubility rules and Ksp, and predict how dissolved particles change vapor pressure, boiling point, freezing point, and osmotic pressure.
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What this chapter covers
- Concentration Units. Picking the right unit, and knowing which ones change with temperature, is the first step in nearly every solution problem.
- Dissolution & Solubility Rules. Predicting whether something dissolves, and how temperature and pressure change that, appears in both discrete questions and passages.
- Ksp & Precipitation. Ksp turns solubility into an equilibrium calculation, and Q versus Ksp tells you whether a precipitate forms.
- Colligative Properties & the van't Hoff Factor. Colligative properties depend on how many solute particles are present, not what they are. Expect ranking and calculation questions.
Key points to know
- Molarity = mol/L solution; molality = mol/kg solvent
- Molality and mole fraction do not change with temperature; molarity does
- Like dissolves like: polar with polar, nonpolar with nonpolar
- Gas solubility rises with pressure (Henry's law) and falls with temperature
- Ksp = product of ion concentrations raised to their coefficients; solids are omitted
- Q > Ksp means a precipitate forms; Q < Ksp means everything stays dissolved
- Colligative properties depend on particle count, not identity
- Solute lowers vapor pressure and freezing point, raises boiling point
Try a practice question
Molality is defined as moles of solute per
- kilogram of solvent
- liter of solution
- kilogram of solution
- liter of solvent
Show the answer
A. Molality is moles of solute divided by the mass of the solvent in kilograms. Liters of solution is the definition of molarity, and that is the choice students most often confuse it with.
Common questions
What does this chapter cover?
Solutions & Colligative Properties covers Concentration Units, Dissolution & Solubility Rules, Ksp & Precipitation, Colligative Properties & the van't Hoff Factor.
What should I know first?
Molarity = mol/L solution; molality = mol/kg solvent Molality and mole fraction do not change with temperature; molarity does Like dissolves like: polar with polar, nonpolar with nonpolar
21 original practice questions accompany this chapter in the app. Spaced review brings missed ideas back at the right time; it helps memory but cannot promise you will not miss an idea again.