exam 1 stuff
Do catalysts lower or higher the activation energy
Lower
Fun fact, It also increases the frequency factor!
What was the name of the table used in chem 110 to determine limiting reagent?
ICF
Initial Change Equilibrium
What is the units for Kp and Kc?
Trick question!!! There are no units for Kp and Kc
NO!!! only liquids and aqueous can be used
Do catalysts speed up an alpha decay (nuclear decay)?
NO!! catalysts do not have any effect on nuclear decay in general
What is used to relate two equilibrium constants?
PV=NRT
What is the sign on the change of the reactants?
What is the sign on the change of the products?
Reactants always have a negative sign (because reactants are being used up)
Products always have a positive sign (because the products are being created)
Can you include liquids and solids in a Kp expression?
NOOOOO
only gasses can be used in a Kp expression
Can you have an intermediate in a Kc expression?
NO
The reaction rate is defined as...
conversion of reactants to products.
When is Q=Keq?
At equilibrium!
Define Le Chatelier's principle.
"The principle named after him states that if a system at equilibrium is disturbed, it will shift to minimize the effect of the disturbance."
When is Kc=Kp?
When delta n=0
Also fun fact! Kp=Kc(RT)^delta n is the only time we use R=0.08206 Latm/molK in this class!
Products are heavily favored when....
Reactants are heavily favored when....
Equilibrium is when...
Keq>>1
Keq<<1
Keq~1
What is the definition of a mechanism?
A series of elementary steps that make up an overall reaction
What is the definition of Q?
"The reaction quotient Q is the ratio of products to reactants raised to their stoichiometric coefficients for a system which is not at equilibrium" -this is straight from the ebook
What are the three types of disturbances related to Le Chatelier's principle?
adding/removing reactants or products
Temperature
Container size and pressure
Write the Kc expression for the following reaction:
2SO2(g)+O2(g)↽−−⇀2SO3(g)
Kc=[SO3]2/ [SO2]2[O2]
When manipulating Keq...
What do you do when you reverse a reaction?
What do you do when you change the coefficients?
What do you do when you combine two reactions?
Reverse a reaction? take the inverse of Keq!
Change the coefficients? Take Keq to the power of whatever factor you changed it by.
Combine two reactions? multiply the Keq's together
What are the two requirements for a reaction to occur?
1. a collision with enough energy to overcome activation energy.
2. a proper orientation
If Q<K.......
If Q=K.....
If Q>K......
If Q<K....... Not enough products!! The reaction will proceed to the right (products)
If Q=K..... The reaction is at equilibrium!! Concentrations will remain constant
If Q>k... Too many products!! The reaction will proceed to the left (reactants)
N2O4(g)->2NO2(g)
colorless brown
An equilibrium mixture of N2O4 (colorless) and NO2 (brown) on the left is compressed to half its volume. What color is the mixture at first and what color is the mixture after allowing to reach equilibrium again?
At first: Immediately after compression, the mixture appears darker because the same number of brown molecules is squished into half the original volume, making the color more intense.
After reaching equilibrium: Compression doubles the pressure, after which the system responds by shifting the equilibrium toward the dimer reactant (colorless N2O4), diminishing the total number of molecules in the container.
Ag+ (aq)+Cl- produces AgCl (s).
What is the Kc expression
Kc= 1/ [Ag+] [Cl-]
Thinking about the k of the forward and reverse reactions, how do Kf and Kr relate to Keq?
Keq=Kf/Kr
Remember: forward rate=reverse rate at equilibrium