list chemical bonds from strongest to weakest
ionic, covalent, hydrogen bonds, london dispersion, and van der waal
When you take something away from a system at equilibrium, the system...
shifts in such a way as to replace what you've taken away.
When you add something to a system at equilibrium, the system...
shifts in such a way as to use up what you've added.
A closed container of ice and water at equilibrium. The temperature is raised.
Ice + Energy -> Water
The equilibrium of the system shifts to the right to use up the added energy.
LeChatelier's Principle
When a system at equilibrium is placed under stress, the system will undergo a change in such a way as to relieve that stress
Q = (?Hv or ?Hf)(n)
Q is the total heat in or out, n is the number of moles, and ?Hv or ?Hf are the molar enthalpies of vaporization and fusion
Increase in pressure leads to...
an increase ?Hv and an increase in boiling point
Decrease in pressure leads to...
a decrease in ?Hv and a decrease in boiling point
Equilibrium
the dynamic condition in which BOTH processes occur at EQUAL rates
Boiling Point
the temperature at which the vapor pressure equals the atmospheric pressure.
water molar enthalpy of vaporization
40.79 kJ/mol
water molar enthalpy of fusion
6.009 kJ/mol
specific heat of water
4.18 J/g
Phase Change Diagram
Types of Crystals:
ionic, covalent networks, covalent molecular, and metallic
ionic
group 1 or 2 metals combined with group 16 or 17 non-metals
properties: hard & brittle, poor electricity conduction, high melting point, poor heat conduction, strong bonds
covalent network
unit cells are bonded covalently with neighboring unit cells
properties: hard & brittle, high melting point, poor electricity/heat conduction, and STRONG BONDS between stoms
Covalent molecular
held together by dipole and dispersion forces (weak bonds)
properties: soft, low melting point, poor electricity conduction, and poor heat conduction
metallic
metal cations surrounded by a "free-flowing" set of valence electrons
properties: variable hardness & melting point, good conductor of electricity and of heat
Network Solids
Composed of strong directional covalent bonds that are best viewed as a "giant molecule". They are brittle (non-flexible), they do not conduct heat or electricity, and are carbon, silicon-based
amorphous solids
glasses and plastics (not arranged in a regular pattern)
absolute vs gauge pressure
Gauge pressure is the pressure measured relative to atmospheric pressure. Gauge pressure is positive for pressures above atmospheric pressure, zero at atmospheric pressure, and negative for pressures below atmospheric pressure. The total pressure is commo
Solubility Trends
What is special about gas solubility?
When the pressure is increased and the temperature is decreased the gas solubility is increased.
What are the three types of mixtures?
solutions, colloids, suspensions
solution
a homogeneous mixture of two or more substances in a single phase
suspension
If the particles in a solvent are so large that they settle out unless the mixture is constantly stirred or agitated, the mixture is called this
colloids
Particles that are intermediate in size between those in solutions and suspensions form mixtures known as colloidal dispersions, or simply colloids
Miscible
Liquids that dissolve freely in one another in any proportion (liquids that can dissolve in each other)
Immisicible
Liquids that are not soluble in each other
Molarity
- M = moles(n) of solute/liters(volume) of solution
- mol/L
Molality
- m = moles(n) of solute/kg(mass) of solvent
- mol/kg
What is osmosis?
the diffusion of water through a semipermeable membrane and the water goes from a low concentration to a high concentration
Colligative Properties of Solutions
vapor pressure lowering, boiling point elevation, freezing point depression
Arrhenius acid
a chemical compound that increases the concentration of hydrogen ions, H+, in aqueous solution
Arrhenius base
a substance that increases the concentration of hydroxide ions, OH?, in aqueous solution
Bronsted-Lowry acid
is a molecule or ion that is a proton donor
Bronsted-Lowry base
a molecule or ion that is a proton acceptor
Lewis acid
an atom, ion, or molecule that accepts an electron pair to form a covalent bond
Lewis Base
an atom, ion, or molecule that donates an electron pair to form a covalent bond
conjugate acid
The species that is formed when a Br�nsted-Lowry base gains a proton is the conjugate acid of that base
conjugate base
the species that remains after a Br�nsted-Lowry acid has given up a proton is the conjugate base of that acid
Weak Acids
An acid that releases few hydrogen ions in aqueous solution
Strong Acids
one that ionizes completely in aqueous solution
Weak vs Strong Acids:
When copper is dissolved in acid, what gas is released?
nitrogen dioxide gas
What two things mix together to make a buffer?
Acid & a salt of that acid (one has to be weak) and a base & a salt of that base (one has to be weak)
pH equation
pH = -log[H+]
What do you do to get the concentration when given the pH?
10^-pH
kw=?
[H3O+ ][OH- ] = 1.0 x 10^-14 M
Calculating [H3O+] and [OH-]
pH
the negative of the common logarithm of the hydronium ion concentration, [H3O+]
pOH
the negative of the common logarithm of the hydroxide ion concentration, [OH?]
Hydrolysis
A reaction between water molecules and ions of a dissolved salt
Finding k (aA + bB -> cC + dD)
k = [C]^c [D]^d / [A]^a [B]^b
What is included when writing the chemical equilibrium expression?
gases, not solids or liquids
What happens when ka is higher?
The acid is more soluble
What happens when a substance gives off a lot of energy when it is forming?
It is stable
What are enthalpies?
They are in molar (per mole of formation or per mole of reactant)
enthalpy of reaction
the quantity of energy transferred as heat during a chemical reaction
entropy
S, can be defined in a simple qualitative way as a measure of the degree of randomness of the particles, such as molecules, in a system
What happens when more articles are around or there are more spaces for them to go?
There is more entropy
Qualitative predictions - entropy will be positive IF there is...
melting, vaporization, sublimation, temperature increase, and an increase in the number of gas molecules
Energy Diagram
The rate of reaction is influenced by the following factors:
nature of reactants, surface area, temperature, concentration of reactants, and the presence of catalysts
How does the rate determining step help determine the rate law?
It will be based upon its coefficients
order
The power to which a reactant concentration is raised
order of reaction
the sum of the reactant orders
Identify the oxidation and reduction half reactions in the following redox reaction
Zn + Cu^2+ -> Zn^2+ + Cu
Oxidation
Processes in which the atoms or ions of an element experience an increase in oxidation state are oxidation processes
reduction
Processes in which the oxidation state of an element decreases are reduction processes
What makes a redox reaction a redox reaction?
The change in oxidation states, so if there is no change in the oxidation states in the reaction then it is not a redox