Chem 112 Exam 2 Flashcards
When we double the quantities of reactants and products in a reaction, what happens to the value of the equilibrium constant?
The equilibrium constant is squared
What is a homogenous equilibrium?
When all of the reactants and products are in the same phase
What is the general form for the equilibrium constant?
Kc=[products]/[reactants]
Does the equilibrium constant, Keq depend on temperature?
yes
Fill in the blank: The equilibrium constant and the reaction quotient have the same ____________, but the concentrations in the ____________ can be the concentrations at ___________, not just at _________
mathematical form, reaction quotient, anytime, equilibrium
(The equilibrium constant and the reaction quotient have the same mathematical form, but the concentrations in the reaction quotient can be the concentrations at any time, not just at equilibrium)
If Q > Keq what does this say about the equilibrium? does the reaction shift?
The system is NOT at equilibrium and the system will produce more reactants to reach equilibrium (shift to the left)
What is the relationship between the dissociation of acetic acid and water?
acetic acid does not dissolve much in water
If Keq > Q what holds true of the system?
The reaction is not at equilibrium and will shift to the right
Make sure Keq is on the left side of >/< symbol to match up to arrow
If Keq = Q then what hold true of the system?
System is at equilibrium and will NOT shift
What will increase the production of ammonia from nitrogen and hydrogen gas?
cooling down the reaction, adding more reatants, increasing partial pressure of reactants
True or false: the addition of an inert gas causes perturbation in a gaseous equilibrium
false
True or false: a gaseous equilibrium respond to an increase in pressure by shifting to the side of equilibrium with fewer moles of gas particles
true
True or false: Increasing the concentration of products in a system at equilibrium makes the equilibrium constant larger
False
True or false: adding more aqueous products to a system at equilibrium causes a shift toward the reactants
True
Are all exothermic processes spontaneous?
No
True or false: if the temperature increases during a process, that process is spontaneous
true
Fill in the blank: a spontaneous process occurs under a ______________
Specific set of conditions
What type of reaction will proceed without any outside intervention?
One that is spontaneous in the forward direction
What are the units for enthalpy?
kj/mol
What type of process can do work and what type of process requires work?
A spontaneous process can do work and a nonspontaneous process requires work
True or false: a spontaneous process can happen slowly
Yes, speed of rxn does not change whether the process is spontaneous or not
What is a restatement of the first law of thermodynamics?
Energy can be converted to a different form but not created or destroyed
What is the third law of thermodynamics?
The entropy of a perfect crystalline substance is equal to zero at absolute zero
True or false: the following relationship is correct: Ssurr=-Hsys/T
True
True or false: For two substances in the same phase, and with similar molar masses, the substance with less complex structure has greater standard entropy
False
Fill in the blank: A molecule of O2 has less ______ _______ than a molecule of F2
Motional Energy
Fill in the blank: a higher temperature correlates with a ______ average molecular speed
Higher
What is entropy a measure of?
How spread out or dispersed the system’s energy is
Fill in the blank: For two monatomic species, the one with the larger molar mass has the ________ standard entropy
Greater
Is there a difference between Gibbs free energy and free energy?
No, but make sure they are in fact asking about free energy and NOT standard free energy
What is the standard free energy change of a reaction?
It is the energy change in a reaction that occurs during standard-state conditions
When is Gibbs free energy spontaneous? When is it at equilibrium?
DeltG>0 non-spontaneous in the forward direction, spontaneous in the reverse direction
DeltG<0 spontaneous in the forward direction, non-spontaneous in the reverse direction
DeltG=0 reaction is at equilibrium, not spontaneous in any direction
When both enthalpy and entropy change are negative, what is the spontaneity of the reaction?
It can be either spontaneous or nonspontaneous depending on the temperature
For the following reaction, Kp=0.113 at 25*C, and the standard free energy change is 5.4 kj/mol. If Todd does an experiment where the initial pressures are PN2O4=0.452 atm and PNO2=0.122 atm, what are the correct units of the free energy change of the reaction? N2O4(g)–>2NO2(g)
kj/mol
Fill in the blank: If Q is positive then _________ are favored at equilibrium
Products
How is free energy change of a reaction calculated?
DeltG=G°+RTlnQ
True or false: Even if a system starts out with all reactants and products in their standard states, as soon as the reaction begins, standard state conditions no longer exist.
True
True or false: the sign of DeltG tells us the same thing as the comparison of Q and K values
True
Choose: The size of the equilibrium constant (does/does not) vary with temperature
Does
What is the relationship between the equilibrium constant and the standard free energy?
When DeltG°=0 then K = 1
When DeltG°>0 then K < 1
When DeltG°<0 then K > 1