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Chemical Kinetics, EQ, And Thermochemistry


General Chemi Stry Cha
  
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Name all the reaction orders
 

Zero order
First order
Second order
Higher order
Mixed order
M
 

Molarity
mol solute/L of solution
Zero-Order reactions
 

has a constant rate, independent of the reactants concentration.
r = k
What are the units of k?
 
Msec-1
Radioactive decay
 

[At] = [Ao] e-kt
[Ao] is the initial concentration of A
[At] is the concentration of A at time T
k is the rate constant
t is elapsed time
products < reactants
 

exothermic (-)
products > reactants
 
endothermic (+)
What are the factors affecting reaction rate?
 

reactant concentration
temperature
medium
catalyst
Equilibrium Expression
 
Products / Reactants
What type of states don't appear in the equilibrium constant?
 
liquids and solids
Le Chatelier's principle
 
A system to which stress is applied tends to change to relieve the applied stress.

A + B ---> C + D
<----
If more A is added
 
Then the equilibrium will switch to the right
Change in pressure and volume
 
Inverse to one another. If pressure increases, volume will decrease. If pressure or volume is increased the equilibrium will go to the least amount of moles.
Change in Temperature
 

In an exothermic reaction:
If the temperature increases the EQ will go to the left. If the temperature decreases the EQ will go to the right.
Equation to determine the decay constant
 
t1/2 = 0.693 / k
What types of systems exist
 

isolate, closed, and open
isolated- neither energy or matter can be exchanged
closed- only energy can be exchanged
open- everything can b exchanged
isothermal
 
occurs when the temperature of the system remains constant
adiabatic
 
occurs when no heat exchange occurs
isobaric
 
when the pressure of the system remains constant
Heat is measured in?
 
calories (cal) or Joules (J)
Measuring calorimetry or heat changes
 
q = mc(delta)T
Enthalpy
 
delta H = H of products - H of reactants
Hess's Law
 
States that enthalpies of reactions are additive.
Entropy is the measure of?
 
Disorder or randomness. The greater the entropy the more disorder.
What's the second law of thermodynamics
 
all spontaneous process proceed such that the entropy of the system plus its surrounding increases
Gibbs Free Energy equation
 
deltaG = deltaH - TdeltaS
If delta G is negative
 
the reaction is spontaneous

delta H delta S
- +
+ -
+ +
- -
 

spontaneous all the time
nonspontaneous all the time
spontaneous at high T
spontaneous at low T
ΔG₀
 
ΔG₀ = - R·T·ln(Keq)
ΔG
 
ΔG₀ + R·T·ln Q

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