Gen Chem Quicksheets Flashcards
System
Matter being observed
Surroundings
Everything outside of system
Isolated system
System can’t exchange energy (heat and work) or matter with surroundings
Closed system
System can exchange energy (heat and work) but not matter with surroundings
Open system
System can exchange energy and matter with surroundings
First law of thermodynamics
/\U=Q-W
Constant temp implies what about the energy of the system?
Constant internal energy
Adiabatic process
No heat exchanged b/w system and environment /\U=-W (work done on the system). Hyperbolic graph on P vs V graph
Isothermal process
Constant temp /\U=0 so Q=W. Hyperbolic curve on P vs V graph
Isobaric process
Same pressure. Flat line on p vs v graph
Isovolumetric process
Isochoric, constant volume, no work is performed /\U=Q. Vertical line on p vs V graph
State functions (mnemonic)
When I’m under Pressure and feeling dense, all I want to do is watch TV and get HUGS
Pressure, density, temperature, volume, enthalpy, internal energy, Gibbs free energy, entropy
Standard conditions
25 Celsius (298 K), 1 atm, 1 M
STP
Standard temperature and pressure - 0 celsius (273 K), 1 atm
Is evaporation endo or exothermic?
Endothermic
Sublimation
solid - gas phase
Temperature
Average kinetic energy of particles of a substance
Heat
Transfer of energy from 1 substance to another
Zeroth law of thermodynamics
Objects are in thermal equilibrium only when their temperatures are equal
Equation for heat transfer
Q=MCAT
Specific heat of water
1 cal/gK
Calorimetry
Process of measuring transferred heat
Equation for heat during phase changes
Q=mL (latent heat: enthalpy of an isothermal process cal/g)
Enthalpy
Heat changes at constant temperature
Change in enthalpy of a reaction equation
/\Hrxn = /\Hproducts - /\Hreactants
Bond dissociation energy
Average energy required to break a particular type of bond b/w atoms in the gas phase
Bond beak is endo/exothermic? Bond forming is endo/exothermic?
Endo, exothermic
How to find the change in enthalpy of a reaction with bond breaking/forming?
/\Hrxn =/\H bonds broken - /\H bonds formed
Second law of thermodynamics
Energy will spread out from 1 point
Entropy
Spontaneous dispersal of energy at a specific temperature: how much or how widely energy is spread out
Equation for change in entropy
/\S = Qreversible/temp
How to calculate entropy of a reaction
/\Srxn = /\Sproducts - /\Sreactants
Equation for Gibbs free energy (mnemonic)
Get Higher Test Scores
/\G = /\H -T/\S
Standard Gibbs free energy from equilibrium constant
-RTlnKeq
Gibbs free energy from reaction quotient
/\Grxn + RTlnQ = RTln (K/Q)
precipitation reaction
formation of a solid from an aqueous solution
displacement reaction
displacement of shuffling of an atom or group from 1 molecule to another
redox reaction
changing the oxidation states of the elements
planck’s quantum theory
energy emitted as electromagnetic radiation from matter exists in discrete bundles called quanta
balmer series
group of hydrogen emission lines corresponding to transitions from upper levels n>2 to n=2
lyman series
group of hydrogen emission lines corresponding to transitions b/w upper levels n>1 to n=1
heisenberg uncertainty principle
impossible to determine which perfect accuracy the momentum and position of an electron simultaneously
4 quantum numbers
n - shell
l - subshell (from 0 to n-1 or 0=s, 1=p, 2=d,3=f)
ml - orbital between -l and l
ms - +1/2 or -1/2
max # electrons in an energy level
2n^2
max # elections in a subshell
4L+2
what is the only periodic trend that goes opposite of all the others? describe
atomic radius! decreases from L to R and B to T while everything else increases
hund’s rule
fill up orbitals halfway with parallel spins first
octet rule
an atom will bond until it has a full outermost shell, an atom wants to have a configuration like a noble gas
steps to draw lewis structure
- write skeletal structure
- count all valence e-
- draw single bonds
- complete octets of all atoms
- extra e- on the central atom
formal charge
charge an atom would have if all the electrons in bonds were shared equally
polar covalent bond
bonding electron pair NOT shared equally and pulled more to an electronegative atom
angle between e- pairs of:
linear
trig planar
tetrahedral
180
120
109.5
chelation
central cation can bond to same ligand multiple times
dispersion forces
bonding electrons in covalent bonds not actually shared equally tho they appear that way, “DISPERSED” randomly and causes really short polarization, form dipoles
basic rate law equation
rate = k[A]^x[B]^y
x and y and k determined experimentally
combustion rxn
fuel + oxidant makes oxide and water (CO2 and water)
combination rxn
2 or more rxns form 1 product
decomposition rxn
compound breaks down into 2 or more substances as a result of heat or electrolysis
single-displacement rxn
atom (ion) replaced by an atom or another element
Double-displacement rxn
metathesis - switch 2!
spectator ion
ion doesn’t take part in the net rxn but remains in solution
neutralization rxn
specific double-displacement occurs when an acid reacts with a base to produce salt and water
what factors affect the rxn rate
reactant conc, temp, medium, catalysts
catalyst
not consumed, lower activation energy barrier
Kc
equilibrium constant - conc of products/reactants
what does not appear in equilibrium constant expressions?
solids or liquids
le chatelier’s principle
direction of rxn at equilibrium when subjected to stress will change to relieve the applied stress
law of conservation of energy
energy neither created or destroyed, types of energy are interconvertible
hess’s law
enthalpies of rxn’s are additive, a reversed rxn has the same magnitude of enthalpy with the opposite sign
Ideal gas law
PV=nRT
deviations on ideal gas law due to pressure
as pressure of a gas increases -> particles pushed close together, gases volume less than predicted, by ideal gas law cuz intermolecular attractions!
deviations on ideal gas law due to temperature
as temp decreases -> velocity of gas decreases, intermolecular forces increase! so smaller volume than predicted by ideal gas law
as temp extremely low -> larger volume of gas particles than expected
1 mol gas at STP = ? L
22.4
molality
moles solute/kg solvent
raoult’s law
partial vapor pressure of each liquid component in a mixture is based on its mol fraction
diffusion
gas molecules distribute thru a volume by random motion
effusion
flow of gas particles under pressure from 1 compartment to another thru small opening
normality
gram equivalents solute/L of solution
arrhenius acid or base
acid - produce excess H+
base - produce excess OH-
bronsted-Lowry acid or base
acid - donates H+
base - accepts H+
Lewis acid or base
acid - e-pair acceptor
base - e-pair donor
pH =
-log[H+] = log(1/[H+])
pOH =
-log[OH-] = log(1/[OH-])
Kw =
[H+][OH-]=10^-14
pOH +pH =
14
hydrolysis
reverse reaction of a neutralization - salt and water react to give acid and base
amphoteric
act as acid or base
oxidizing agent
reduced, causes another atom to be oxidized
reducing agent
oxidized, causes another atom to be reduced
reduction potential
tendency to acquire electrons and be reduced
emf
standard reduction potentials used to calculate electromotive force = Ered, cathode - Ered, anode
galvanic cell
spontaneous, supplies energy for work, energy harnessed by redox half-rxns
electrolytic cell
nonspontaneous, needs electrical energy to react
