Solutions and Solutes Flashcards

A solution is a homogeneous mixture consisting of a solute and a solvent.
Solute: The substance that gets dissolved. A solution can contain more than one solute.
Solvent: The substance that does the dissolving, typically present in a greater amount.

Immiscible: Substances that do not mix together.
Suspension: A heterogeneous mixture where layers form (e.g., oil and vinegar, sand and water).
Heterogeneous: Different throughout.
Colloid: Appears homogeneous but is heterogeneous upon closer inspection (e.g., milk).
Soluble/Miscible: Substances that mix together to become homogeneous (e.g., salt and water, sugar and water).
"Like dissolves like": Molecules with similar intermolecular forces tend to dissolve in each other.

Molecular Properties:
- Many, but not all, ionic substances will dissolve in water due to attraction to water molecules.
- Many nonpolar and covalent compounds do not dissolve in water.
- Nonpolar substances are more attracted to each other than to water. Water is more attracted to itself than to nonpolar substances.
Temperature:
- As temperature increases, solubility generally increases.
- Higher temperatures cause solvent molecules to move faster, speeding up the dissolving of the solute (e.g., hot water vs. cold water).
Particle Size:
- As particle size decreases, solubility increases.
- Larger particles require more collisions from the solvent to dissolve (e.g., fine salt vs. chunky salt).
Mixing/Shaking:
- Increased shaking/mixing increases solubility.
- Increased movement leads to more collisions between solute and solvent (e.g., protein shakes).

Solution concentration refers to the amount of solute dissolved in a specific amount of solution.
It depends on the quantity of solute and the quantity of solvent.

One way to measure concentration.
ppm or mg/L.
Measurement of the mass of a chemical or contaminant per unit.
Formula: $PPM = \frac{\text{grams of solute}}{\text{grams of solution}} \times 1,000,000$

Another way to measure concentration; defined as moles per liter.
Units: mol/L or M.
Higher concentration: add more solute.
Lower concentration: add more solvent.
Formula: $\text{Molarity} = \frac{\text{moles of solute}}{\text{liters of solution}}$

As the solute increases, the solution volume doesn't change, but the molarity increases.
As the solute decreases, the solution volume doesn't change, but the molarity decreases.
If the solute doesn't change, and the solution volume decreases, the molarity increases.
The solute and molarity have a direct relationship, while the solution volume and molarity have an inverse relationship.