Properties of Solutions

Flashcards covering key vocabulary and concepts from a lecture on the properties of solutions.

Solution

A homogeneous mixture where components are uniformly intermingled.

Solvent

The substance in which a solute dissolves.

Solute

The substance that dissolves in a solvent.

Dilute

Qualitative term for a solution with relatively little solute.

Concentrated

Qualitative term for a solution with a relatively large amount of solute.

Mass percent

Percent solute by mass in the solution.

Mole fraction

Ratio of the number of moles of a given component to the total number of moles of solution.

Molality (m)

Number of moles of solute per kilogram of solvent.

Molarity (M)

Moles of specific solute per liters of solution.

Molarity

The concentration of a particular chemical species.

Formality

The concentration of the entire substance without regard to its specific chemical form.

Normality

Based on the number of moles of the active part of the solute, called a chemical equivalent.

Step 1 of Solution Formation

Breaking up the solute into individual components.

Step 2 of Solution Formation

Overcoming intermolecular forces in the solvent to make room for the solute.

Step 3 of Solution Formation

Allowing the solute and solvent to interact to form the solution.

Enthalpy (heat) of solution (Hsoln)

Overall enthalpy change associated with the formation of the solution.

Enthalpy (heat) of hydration (Hhyd)

Combines the terms ΔH2 (for expanding the solvent) and ΔH3 (for solvent-solute interactions).

Hydrophobic

Nonpolar materials like vitamin A

Hydrophilic

Polar substances like vitamin C

Henry’s Law

The amount of gas dissolved in a solution is directly proportional to the pressure of the gas above the solution.

Temperature Effects for Aqueous Solutions

The effect of temperature on the solubility in water of several common solids

Nonvolatile Solute

Lowers the vapor pressure of a solvent.

Ideal Solution

Any solution that obeys Raoult’s law.

Tendency of the solvent molecules to escape will be lowered more than expected

A negative deviation from Raoult’s law.

Positive deviations from Raoult’ s law

The molecules in the solution have a higher tendency to escape than expected.

Colligative Properties

Freezing-point depression, boiling-point elevation, and osmotic pressure.

Colligative Property

Depends only on the ratio of the number of particles of solute and solvent in the solution, not the identity of the solute.

Boiling-Point Elevation

A nonvolatile solute elevates the boiling point of the solvent.

Molal Boiling-Point Elevation Constant

The constant is characteristic of the solvent

Freezing-Point Depression

The resulting solution does not freeze at 0℃ because the water in the solution has a lower vapor pressure than that of pure ice.

Osmosis

The flow of solvent into the solution through the semipermeable membrane.

Osmotic Pressure

The excess pressure.

Isotonic Solutions

Solutions that have identical osmotic pressures.

Reverse Osmosis

If a solution in contact with pure solvent across a semipermeable membrane is subjected to an external pressure larger than its osmotic pressure.

Van’t Hoff Factor

Relationship between the moles of solute dissolved and the moles of particles in solution

Ion Pairing

The best explanation is that ion pairing occurs in solution

Tyndall effect

The scattering of light by particles

Colloidal dispersion, or Colloid

A suspension of tiny particles in some medium

Coagulation

The destruction of a colloid suspension into a precipitate