General Chemistry

Unsaturated solution

Has less than the maximum amount of solute dissolved in a solvent.

Saturated solution

Has the maximum amount of solute dissolved in a solvent. Adding more solute leads to it remaining undissolved.

Supersaturated

Happens when heated, the solution contains more dissolved solute than they can normally hold at a given temperature and pressure.

Crystallization

This occurs when a dissolved solute comes out of the solution. These crystals are generally formed by manipulating temperature or pressure.

What are the soluble salts?

Group 1 metal cations, NO₃- CLO₄- C₂H₃O₂- and NH₄- Note soluble component trumps the insoluble component.

What are the insoluble salts?

Ag+ Pb²⁺ Hg²⁺ OH^- S^2- CO₃^2- PO₄^3-

Electrolytes

Substances that have a natural positive or negative electrical charge when dissolved in water.

Strong Electrolytes

Fully dissociate in water

• Soluble ionic compounds

• Strong acids

• Strong Bases

Weak electrolytes

Incompletely dissociate in water

• Weak acids

• Weak bases

Non-electrolyes

Do not dissociate in water

• Molecular compounds that are not acidic or basic eg. C₆H₁₂O₆, CH₃OH, etc.

Strong Acids

HCl, HBr, HI, HClO₄, HClO₃, H₂SO₄, HNO₃.

Strong Bases

Group I Metal Hydroxides (metal + OH), Ca(OH)₂, Sr(OH)₂, Ba(OH)₂.

Weak acids

HF, HCN, CH3COOH, etc.

Weak bases

NH3, CH3NH2, etc.

Phases solubility Rules

• Solids are more soluble at higher temperatures

• Gases are more soluble at lower temperatures

• Gases are more soluble at higher temperatures

Spectrophotometry

A method that measures how much a chemical substance absorbs light by measuring the intensity of light as a beam of light passes through a sample solution. A spectrophotomer measures how much light is sent into the solution and how much light comes out.

Beer’s law

States that light absorption is directly proportional to path length and concentration of solution.

A = Elc

A= absorbance

E= molar absorptivity

l = path length

c = concentration of solution

Like dissolves like

• Polar solvents dissolve polar solutes

• Non-polar solvents dissolve non-polar solutes

• Polar and non-polar do NOT dissolve in each other.

Heterogenous mixtures

Have particles distributed non-uniformly. They can be physicallly seperated and have visually distinguishable components.

Homogenus mixtures

Have their particles distributed uniformly. These mixtures cannot be physically seperated and the individual components cannot be identified.

Molarity

M= moles of solute / liters of solution

Molality

m = moles of solute / kilograms of solvent

Dilution formula

M1 V1 = M2 V2

M is molarity

V is volume

Normality

N = n x M

n = number of equivalents (how many H+ it takes/dissociates)

M = molarity

Colligative properties

Depend on the concentration of solute molecules or ions, but not on the identity of the solute itself.

• Vapor-pressure depression

• Boiling point elevation

• Freezing point depression

• Osmotic pressure

Non-colligative properties

Depend on the identity of the dissolved species and solvent.

• Surface tension

• Viscosity (measure of the fluid’s resistance to flow)

• Solubilty

• Voltality (how easily a substance evaporates)

• Color and density

Boiling point

Point where the vapor pressure equals the atmospheric pressure. When elevation increases, vapor pressure decreases and boiling point decreases. As elevation descreases, atmoshperic pressure increases and boiling point increases.

Vapor pressure depression

The vapor pressure of a pure solvent is greater than the vapor pressure of a solution containing non-volatile solutes. As vapor pressure increases, boiling pressure decreases. If a solution has a dissolved solute, it lowers the vapor pressure.

Raoult’s law

Use to calculate the new vapor pressure after a solute has been added.

P_A= X_AP_A^∘

P_A= vapor pressure of the solution after the solute has been added

X_{A =} mole fraction of the solvent

P_A^∘ = pure vapor pressure of solvent

Boiling point elevation

When a non-volatile solute is added to a solution, it increases the solution’s boiling point.

ΔT_b = k_bim