Mini Test 3 Flashcards
types of motion
translational
rotational
vibrational
Laws of thermodynamics
1st: energy is conserved
2nd: The total entropy of the universe increases in any spontaneous process
3rd: A perfect crystal has an entropy of 0
enthalpy
the total amount of energy in a system
endo (pos)
exo (neg)
entropy
the dispersion of energy in a system
increases (pos) decreases (neg)
Gibbs free energy
the energy available to do work
G>0 non spontaneous
G<0 spontaneous
deltaG=deltaH-TdeltaS
this is the driving force of equilibrium, any amount of Gibbs free energy will be used to establish equilibrium. It is when G=0 when equilibrium has been established
equilibrium
- simultaneous forward and reverse reactions
- @ equilibrium concentrations are constant
- forward and reverse reactions have equal rates
rate laws are equal
k[A][B]=k2[C][D]
**Concentrations aren’t the same at equilibrium but rates are
K (the equilibrium rate constant)
products^order/reactants^order
can be concentrations or pressure-based
shows which side of the equation is being favored, or making the most
Q (reaction quotient)
the numerical value of mass action expression for any values of the concentration of reactants and products @ initial conditions
K>Q form products
K<Q form reactants
K=Q equilibrium
homogeneous equilibrium
products and reactants are in the same phase
heterogeneous equilibrium
products and reactants are in different phases
anything that isn’t a gase (liquid (water) and solid can be canceled out as one)
le chateliers prinicple
disturbing all equilibrium systems by changing concentration, pressure, or temperature results in an equilibrium position shift which contracts disturbance
“shifts” regarding the less amount, need more to be balanced out
EX. shifting to the right means that more products will be made to set the equilibrium
concentration
K DOESNT CHANGE
adding more reactant=more product (shifts to the right)
removing reactant= more reactant (shifts to the left)
pressure/volume
K DOESNT CHANGE
decreasing volume, increasing pressure=shifts to side with fewer moles
increasing volume, decreasing pressure=shifts to side with more moles
temperature
CHANGES K
endothermic: increase T = increase K,
decrease T = decrease K
exothermic: increase T = decrease K
decrease T = increase K
**Think about the heat as a reactant or product when considering which side it shifts to
REMEMBER: temperature changes K because it changes the activation energy. When thinking about the Arrhenius equation, this means that the k will change therefore the ratio of k/k will also change and K will be different than that at a different temp
also think about the van hoff equation, relating the K to T, proving that K will only change with Temp
catalyst
K DOESN’T CHANGE
lowers the activation energy, so it speeds up the reaction (temp remains the same)
