first q Flashcards
Kinetic Molecular Theory
tiny particles always in motion
Five Assumptions of KMT
- large number tiny spherical particles far apart
- constant rapid motion random directions
- elastic (conserved KE)
- no force of attraction or repulsion
- avg KE is dependent on temperature
State of substance depends on
the balance between KE and Inteparticle energies (IMF)
attractive forces between molecules
Intermolecular forces
Types of Intermolecular forces
Nonpolar (dispersion)
Polar (dipole-dipole) → Hydrogen bond (H to NOF)
Ion-dipole (ion + dipole)
Ionic (Ionic bond)
Vander Waals forces
dispersion, dipole-dipole
↑ no of electrons = _ molar mass = _ melting/boiling point
↑, ↑
The ease with which an atom or molecule can be
distorted
polarizability
Factors affecting dispersion
no of electrons
size shape
Properties of liquids
Surface Tension
Viscosity
Vapor Pressure
Boiling Point
Molar Heat of Vaporization
amount of energy to stretch or increase the
surface of a liquid by unit area
Surface Tension
Viscosity and Molecular Shape
long, flexible molecules tend to have a higher viscosity than those composed of more spherical or shorter-chain molecules. The longer the molecules, the easier it is for them to become “tangled” with one another
Adhesion
unlike molecules
Cohesion
within like molecules
Concave meniscus
U
adhesion > cohesion
convex
∩
cohesion > adhesion
What is boiling point
vapor pressure of the liquid =air pressure above the liquid
Altitude, Atmospheric Pressure, and Boiling Point
Lower altitude = Higher Atmospheric pressure = higher boiling point
Enthalpy of Vaporization; the heat required to induce phase change
Molar Heat of vaporization
Properties of water
Universal Solvent
High Specific Heat - breaks hydrogen bonds, thermal buffer to keep temperatures stable
High Heat of Vaporization - sweating
High Surface Tension -
Less dense as a solid - crystal lattice
Hydrogen bonds form between slightly _ hydrogen atoms and slightly _ atoms
positive, negative
Why does oil not mix with water
like dissolves like, water is polar while oil is not
Crystalline vs Amorphous
Crystalline - long rigid; predictable positions; precise melting points
Amorphous - lack of a well-defined arrangement, unpredictable
Types of crystals
Covalent - atoms - covalent - hard, high - poor c
Molecular - molecules - IMF - soft, low - poor c
Metallic - metal ions - metallic bonds - soft to hard low to high - good c
Ionic - cations/anions - electrostatic force - hard, brittle, high - poor c
examples of covalent crystals
diamond, graphite, silicon carbide, Si, SiO2, Ge
examples of molecular crystals
dry ice, PH3, H2, F2, C6H12O6
molarity
mol/L (solution)
molality
mol/kg (solvent)
mole fraction
mol/mol total
percent concentration
w/w v/v w/v (g/ml)
adding a non volatile solute
lowers vapor pressure
elevates boiling point
depresses freezing point
increase osmotic pressure
pressure to prevent osmosis from occurring
osmotic pressure
weak electrolytes produce __ while nonelectrolytes __
few ions, do not produce ions
