Essential Concepts and Calculations in Solution Chemistry

1) Solution

A homogeneous mixture of two or more substances formed by a solute dispersed in a solvent.

2) Tyndall Effect

Visual of a light beam passing through a homogeneous mixture.

3) Concentration

The relationship between the amount of solute and solvent.

4) Dissolution

The process of scattering solute particles within the solvent.

5) Solubility

Expresses the maximum amount of solute that can dissolve in a given solvent.

6) Polar Molecule

A molecule with an uneven distribution of electronic charge along its structure.

7) Non-Polar Molecule

A molecule with a uniform distribution of electronic charges.

8) Types of Concentrations

• Dilute: A solution containing a small amount of solute.
• Saturated Solution: Contains the maximum amount of solute at a given temperature.
• Supersaturated Solution: Contains more solute than it can theoretically hold under stable conditions.

9) Concentration Units

Reflects the amount of solute in relation to the amount of solution or solvent, using units of mass, volume, or moles. They allow for precise determination of solute presence.

10) Percentage Concentration

Expresses the amount of solute in relation to the total amount, calculated per hundred units.

Formulas used:

• % m/m = (mass of solute / mass of solution) x 100%
• % m/v = (mass of solute / volume of solution) x 100%
• % v/v = (volume of solute / volume of solution) x 100%

11) Mole Fraction

Relates the number of moles of solute to the total number of moles in a solution.

X_solute = N_solute / N_total

X_solvent = N_solvent / N_total

X_solute + X_solvent = 1

Where:

• X = Mole fraction
• N_solute = number of moles of solute
• N_solvent = number of moles of solvent
• N_total = total number of moles (N_solute + N_solvent)

To determine the number of moles, the mass and molecular weight are needed: Number of Moles = mass / molecular weight

12) Molarity (M)

Refers to the moles of solute dissolved per liter of solution.

Molarity (M) = N° moles of solute / Volume of solution (L)

Alternatively: M = (millimoles of solute) / (volume of solution (mL))

13) Molality (m)

Refers to the number of moles of solute dissolved per kilogram of solvent.

Molality (m) = (number of moles of solute) / (mass of solvent (kg))

Alternatively: m = (millimoles of solute) / (mass of solvent (g))

14) Normality (N)

Expresses the number of equivalents of solute dissolved per liter of solution.

15) Dilution

The process of preparing a less concentrated solution from a more concentrated one by adding solvent.

16) Indicator

A substance that changes color depending on whether it is in an acidic or basic medium, due to the presence of H+ or OH- ions, respectively.

17) Volumetric Methods

Analytical chemical studies used to determine the concentration of a sample solution by adding a known concentration of another solution.

18) Titration

Involves determining the concentration of an acid or a base using a solution of a base or acid of known concentration, respectively.

19) Categories of Volumetric Methods

a) Precipitation Reactions

Reactions that result in the formation of an insoluble solid.

b) Complex Formation Reactions

Reactions involving the formation of molecules from a large number of atoms during the test.

c) Oxidation-Reduction Reactions

Reactions involving changes in the oxidation states of elements through the gain or loss of electrons.

d) Neutralization Reactions

Reactions that achieve a balance between the amount of acid and base by equalizing equivalents.