Chemical Equilibrium Review Flashcards
What is dynamic equilibrium in a chemical reaction?
A state in which no net change occurs because there are two opposing processes occurring at the same rate.
Rogers, Chem for Eng, Pg. 259
In chemistry what does something in square brackets represent?
The concentration of a substance in units of moles per liter or molarity.
Rogers, Chem for Eng, Pg. 260
What variables is the equilibrium constant dependent upon?
Temperature, initial concentrations, pressure, and the presence of a catalyst.
Rogers, Chem for Eng, Pg. 260
True or False
The equilibrium constant is non-dimensional.
True
Rogers, Chem for Eng, Pg. 260
If the equilibrium constant is very large, then the equilibrium mixture contains mostly ______.
Products
Rogers, Chem for Eng, Pg. 261
If the equilibrium constant is very small, then the equilibrium mixture contains mostly ________.
Reactants.
Rogers, Chem for Eng, Pg. 261
True or False
At a given temperature, the same concentration ratio will always be obtained for a given reaction regardless of the initial concentration of reactants and products.
True.
Rogers, Chem for Eng, Pg. 261
What is meant by the term “forward reaction?”
The amount of reactants decreases while the amount of products increases.
Rogers, Chem for Eng, Pg. 261
What is meant by the term, “reverse reaction?”
The amount of reactants increases while the amount of products decreases.
Rogers, Chem for Eng, Pg. 261
The value of an equilibrium constant at a given temperature is _____ of initial concentrations.
Independent.
Rogers, Chem for Eng, Pg. 262
What is the benefit of knowing the reaction quotient?
Knowing the reaction quotient allows one to determine whether or not a chemical reaction will occur in the forward or reverse direction.
Rogers, Chem for Eng, Pg. 262
If the reaction quotient is less than the equilibrium constant, how will the reaction proceed?
In the forward direction.
Rogers, Chem for Eng, Pg. 263
If the reaction quotient is greater than the equilibrium constant, how will the reaction proceed?
In the reverse direction.
Rogers, Chem for Eng, Pg. 263
If the reaction quotient is equal to the equilibrium constant how will the reaction proceed?
The reaction is at equilibrium.
Rogers, Chem for Eng, Pg. 263
What is the definition of concentration?
It is the number of moles divided by volume.
Rogers, Chem for Eng, Pg. 268
What is a homogeneous equilibrium state?
A homogeneous equilibrium is one in which all of the reactants and products are the same phase.
Rogers, Chem for Eng, Pg. 269
What is a heterogeneous equilibrium state?
A heterogeneous equilibrium contains a solid or liquid in contact with substances and different phases.
Rogers, Chem for Eng, Pg. 269
In a heterogeneous equilibrium, any solid or liquid is _____ from the Kc or Kp equations.
Omitted
Rogers, Chem for Eng, Pg. 269
True or False
Aqueous solutions are included in the KC or KP equations.
True.
Rogers, Chem for Eng, Pg. 269
Why are all solids and liquids omitted from the Kc/Kp equations?
Because the concentration of any solid or liquid is an intensive property.
Rogers, Chem for Eng, Pg. 269
The mass of a solid or liquid can change during the course of a reaction, however, the concentration (in mol/L) does _______ change.
not
Rogers, Chem for Eng, Pg. 269
True or False?
The equilibrium position does not depend on how much solid or liquid is present. As long as there is some solid or liquid a system can achieve equilibrium.
True
Rogers, Chem for Eng, Pg. 270
What is Le Chatelier’s Principle?
It states that if a system at equilibrium is disturbed by changes in concentration, pressure, or temperature, the system will respond by shifting its equilibrium position in a direction that will counter the disturbance.
Rogers, Chem for Eng, Pg. 283
If products are removed or if reactants are added what will be the relationship between the equilibrium constant and the reaction product? How will the reaction proceed?
Qc < Kc
In the forward direction
Rogers, Chem for Eng, Pg. 284
If reactants are removed or if products are added to an equilibrium mixture, the magnitude of Qc ______. this causes the equilibrium to shift _______, and a _____ reaction occurs.
Increases
left
reverse
Rogers, Chem for Eng, Pg. 284
True or False
An equilibrium will shift to the right (that is, in a forward direction) if the concentration on the reactant side is increased or if the concentration on the product side is decreased.
True
Rogers, Chem for Eng, Pg. 285
What are the three ways that changes in pressure player role in determining the equilibrium position of a gas phase reaction?
- Changes in the partial pressure of a reactant or product gas.
- Addition of a nonparticipating or inert gas.
- Changing the volume of the container.
Rogers, Chem for Eng, Pg. 286
True or False
The addition of nonparticipating gas in reaction increases the total pressure but it has no effect on individual partial pressures.
True
Rogers, Chem for Eng, Pg. 286
The addition of a non-participating substance (such as an inert gas) ______ affect the equilibrium position.
does not
Rogers, Chem for Eng, Pg. 286
Give a definition for partial pressure.
The pressure that an individual gas in a mixture of gases would exert if it were by itself.
Rogers, Chem for Eng, Pg. 286
What would happen if the volume of the container were decreased during a gas equilibrium reaction?
This would cause the total pressure to increase. Le Chatelier’s principle suggests that a system will counter this increase by shifting to the side of the equation with fewer moles of gas.
Rogers, Chem for Eng, Pg. 286
What would happen if the volume of the container were increased during a gas equilibrium reaction?
Increasing the volume of the container causes the total pressure to decrease. The system responds to a decrease in pressure due to expansion by shifting to the side of the equation with more moles of gas.
Rogers, Chem for Eng, Pg. 286
True or False
Neither changes in temperature nor changes in concentration will change the equilibrium constant value.
False. Changing the temperature does change the equilibrium value.
Rogers, Chem for Eng, Pg. 287
An endothermic reaction will respond to an increase in temperature by _______.
Shifting to the right. The equilibrium mixture will contain more products and fewer reactants than the original one at a lower temperature.
Rogers, Chem for Eng, Pg. 287
When the temperature is lowered for an endothermic reaction at equilibrium their reaction ______.
Shifts to the left. The new equilibrium mixture will contain more reactants and fewer products at the lower temperature and the magnitude of the equilibrium constant decreases.
Rogers, Chem for Eng, Pg. 287
For an endothermic reaction, a change in temperature shifts the equilibrium ______ and ______ the magnitude of Keq.
to the right
increases
Rogers, Chem for Eng, Pg. 287
When the temperature is lowered for an endothermic reaction at equilibrium the reaction shifts to the ______ and the magnitude of Keq ______.
left
decreases
Rogers, Chem for Eng, Pg. 287
For an exothermic reaction, heat is written on the ______ side of the equation.
product.
Rogers, Chem for Eng, Pg. 288
For an exothermic reaction, heat is written on the ______ side of the equation.
Reactant.
Rogers, Chem for Eng, Pg. 287
Increasing the temperature of an exothermic reaction causes the equilibrium to shift to the _____, and _____ the equilibrium constant Keq.
left
decreases
Rogers, Chem for Eng, Pg. 288
Decreasing the temperature of an exothermic reaction causes the equilibrium to shift to the ______, and _______ the equilibrium constant Keq.
right
increases
Rogers, Chem for Eng, Pg. 288
True or False:
The addition of a catalyst does not affect the final equilibrium position. A catalyst speeds up a reaction, and egg boiling it to reach equilibrium faster. However, it has no effect on the equilibrium amounts.
True.
Rogers, Chem for Eng, Pg. 288
True or False
in a heterogeneous equilibrium, changing the amount of solid or liquid does affect the equilibrium position.
False. It does affect the equilibrium position.
Rogers, Chem for Eng, Pg. 288
