Kinetic molecular model- explains the properties of solids and liquids in term of
the intermolecular forces of attraction and the kinetic energy of the individual
particles.
Intermolecular forces- attractive forces between neighboring particles of one or
more substances.
Intermolecular Forces of Attraction
Van der Waals- the intermolecular forces of attraction in a pure substance
Dipole-dipole forces- exist between polar molecules.
Polar molecules- difference in electro negativities of their component atoms are
arranged in space.
Hydrogen bonds- is a special type of dipole-dipole interaction that exists only in
molecules that contain a hydrogen atom bonded to a small, electronegative atom.
Five to ten times stronger than other dipole-dipole attraction.
Is not a real chemical bond participated in by electrons
Is intermolecular in nature.
Ion-Dipole Forces- acts between an ion and a polar molecule.
Becomes stronger either as the charge of the ion increase, or as the magnitude of
the dipole moment of the polar molecule increases.
London Dispersion Forces- or simply dispersion forces, are intermolecular forces of
attraction that exist between all atoms and molecules.
Nonpolar molecules- electron density is uniform and symmetrical.
Temporary dipole- also called instantaneous dipole, molecule momentarily acquires a
non-uniform electron density.
Intermolecular Forces and Properties of Liquids
Surface tension- property of liquid to resist an external force and thus assume a
lesser surface area.
Viscosity- is the resistance of a liquid to flow.
Vapour Pressure- pressure exerted by its vapour when in equilibrium with its liquid
or solid.
Boiling Point- is the temperature at which its vapour pressure is equal to the
external of atmospheric pressure.
Heat of Vaporization (Molar heat of vaporization ΔΗᵥₐₚ) – is the amount of heat
required to vaporize one mole of a substance at its boiling point.
Pure water- is a colorless, odourless, and tasteless liquid.
Water molecule- has a bent shape, with two partially positive hydrogen atoms and a
partially negative oxygen atom.
Types and Properties of Solids
Amorphous Solids- have considerable disorder in their structure.
Are formed rather rapidly that its constituent particles do not have time to align
or organize into a more definite crystalline lattice.
Crystallography- is a specialization that studies the properties of a substance
based on the three-dimensional arrangement of atoms that comprises it.
Crystallographers, the one who studies crystallography.
Crystalline Solids- have a highly regular arrangement of particles.
Has a well-defined crystal lattice.
Lattice- is a three-dimensional system of points designating the positions of the
components that makeup a crystal.
Unit cell- is the smallest repeating unit of lattice.
Ionic Solids- have ions at different points of the lattice.
Molecular Solids- has a discrete covalently bonded molecules at each of its lattice
points.
Metallic Solids- are composed of metal atoms bonded together by metallic bonds.
Network Solids- are covalently bonded atoms that form continuous network.
Group 8A Solids- consist of atoms of noble gases held together by London dispersion
forces.
Phase Changes and Phase Diagrams
Sublimation- go directly from being solid to vapour.
Phase Diagram- is a graphical representation of the pressure-temperature
relationships that apply to the equilibria between the phases of a substance.
Triple point- where all the three phases coexist in equilibrium.
Critical point- the temperature-pressure condition at and above which the vapour of
the substance cannot be liquefied no matter how much pressure is applied.
Supercritical- distinct liquid and vapour phases is no longer evident.
Supercritical fluid- is a substance that’s has a temperature above its critical
temperature and a density near its liquid density.
Type of Solutions
Solution- are mixtures of two or more substances evenly distributed throughout a
single phase.
Solute- is the substance dissolved in a solution
Solvent- is the dissolving medium.
Unsaturated solution- contains less solute than the solvent’s capacity to dissolve.
Saturated solution- contains the maximum amount of solute that the solvent can
dissolve at a certain temperature.
Energy of Solution Formation
Endothermic- require energy to overcome the forces in expanding the solvent and
solute.
Exothermic- the formation of new solute-solvent interaction, which usually releases
energy.
Enthalpy change (ΔH) - involves a heat change
Enthalpy of solution (ΔHₛₒₗₙ) - is the enthalpy change associated with the
formation of the solution. It is equal to the sum of the ΔH values for the three
steps.
ΔHₛₒₗₙ = ΔH₁ + ΔH₂ + ΔH₃
Positive ΔHₛₒₗₙ- signifies an endothermic process
Negative ΔHₛₒₗₙ- indicates an exothermic process
Concentration of Solution
Percent by Mass, Volume, and by Mass-Volume
Formulas:
%w/w=
Soln=
%v/v=
%w/v=
Mole Fraction
ᴀ= =
mole=
MM= no. elementsatomic mass
Molality and Molarity
Molality- is the number of moles of solute per kilogram of solvent.
=
Molarity- is the number of moles of solute per liter of solution.
Parts Per Million
Parts per million (ppm) - express the number of parts of solute per one million
parts of the solution.
Ppm=
Example;
Solution Stoichiometry
Example:
Calculate the mass (in grams) of Ca(NO₃)₂ that can be produced by reacting 1.36mL
of 4.00 M HNO₃ with excess Ca(OH)₂. (MM of Ca(NO₃)₂ = 164.1 g/mol)
Solution:
Write first the balanced equation for the reaction.
2HNO₃ + Ca(OH)₂ → 2H₂O + Ca(NO₃)₂
Three general steps in solving the problem:
Step 1: use the molarity and volume of the solution to get the number of moles of
HNO₃.
Mole HNO₃ = (molarity)(volume of sol’n in L)
= (4.00 M)(0.136 L)
= 0.544 mol
Step 2: find the number of moles of Ca(NO₃)₂ using the stoichiometric factor.
Mole + Ca(NO₃)₂ = (0.544 mol HNO₃)
= 0.272 mol
Step 3: find the mass of Ca(NO₃)₂ using its molar mass.
Mass Ca(NO₃)₂ = (0.272 mol)(164.1 g/mol)
= 44.6 g
Factors Affecting Solubility
Solubility- is the maximum amount of a solute that can dissolve in a given amount
of solvent at a specific temperature.
Different factors that affect solubility:
Nature of Solute and Solvent
Temperature
Pressure
Colligative Properties of Solution
Colligative properties- quantity-dependent properties, which include vapour
pressure lowering, freezing point depression, boiling point elevation, and osmic
pressure.
Electrolytes- are particles that ionize in a solution; as a result, they conduct
electricity.
Nonelectrolytes- are those that do not ionize at all in solution and thus do not
conduct electricity.
Strong electrolytes- electrolytes that can completely ionize in water such as ionic
compounds, strong acids, and strong bases.
Weak electrolytes- partially ionize in water such as weak acids and weak bases.
Francois-Marie Raoult- French chemist who formulated Raoult’s law.
Vapour Pressure Lowering
Raoult’s law- states that the vapour pressure of a solvent over a solution
(Pₛₒₗᵥₑₙₜ) is equal to the product of the vapour pressure of the pure solvent
(P°ₛₒₗᵥₑₙₜ) and the mole fraction of the solvent in the solution (xₛₒₗᵥₑₙₜ). In
expression.
Pₛₒₗᵥₑₙₜ = xₛₒₗᵥₑₙₜP°ₛₒₗᵥₑₙₜ
For a solution containing only one solute,
xₛₒₗᵥₑₙₜ = 1xₛₒₗᵤₜₑ
where xₛₒₗᵤₜₑ is the mole fraction of the solute. Manipulating the equation gives
Pₛₒₗᵥₑₙₜ = (1xₛₒₗᵤₜₑ) P°ₛₒₗᵥₑₙₜ
= P°ₛₒₗᵥₑₙₜ xₛₒₗᵤₜₑ P°ₛₒₗᵥₑₙₜ
P°ₛₒₗᵥₑₙₜ Pₛₒₗᵥₑₙₜ = = xₛₒₗᵤₜₑ P°ₛₒₗᵥₑₙₜ
The resulting equation suggests that the decrease in vapour pressure () is directly
proportional to the solute concentration.
Freezing Point Depression and Boiling Point Elevation
Freezing point depression constant (Kf) - also termed cryoscopic constant, one mole
of any nonelectrolyte will lower the freezing point of a given amount of solvent by
a constant amount.
The freezing point depression ( is related to the molal concentration of a
nonelectrolyte solute by the following equation:
(=tₛₒₗᵤₜᵢₒₙ tₛₒₗᵥₑₙₜ = (molality)(Kf)
Molal boiling point elevation constant (Kf)- also termed ebullioscopic constant,
one mole of any non-volatile, nonelectrolyte solute will elevate the boiling point
of a given amount of solvent by a constant factor depen
