Unit 2: Chemical Equilibrium Flashcards
Equilibrium constant
K, it is unitless.
Rate constant
k
In equilibrium are the concentrations of products and reactants the same?
No, the concentrations of products and reactants are just constant.
What can effect the equilibrium constant?
Change in temperature
What is heterogeneous equilibria
Reactions with species that are different phases.
What does not appear in an equilibrium constant equation?
Pure solids, liquids, and solvents
Large K?
> 10^3
Intermediate K?
10^-3 to 10^2
Small K?
<10^-4
What happens with a large K?
The reaction proceeds to completion and at eq there will be a large amount of product and a small amount of reactant.
What happens with a small K?
The reaction does not completely proceed and at eq there will be a small amount of product and a large amount of reactant.
Reaction Quotient
Q
If Q < K what happens?
The reaction will go towards the products and the Q will get larger.
If Q > K what happens?
The reaction will go towards the reactants and the Q will get smaller.
What happens if you increase the concentration of a substance?
The reactions shifts away from that substance.
What happens if you decrease the concentration of a substance?
The reaction shifts towards that substance.
What happens if you increase the pressure of the system?
The reaction shifts towards the side with fewer moles.
What happens if you decrease the pressure of the system?
The reaction shifts towards the side with more moles.
What happens if you increase the temperature of the system?
The reaction shifts away from the heat/energy.
What happens if you decrease the temperature of the system?
The reaction shifts towards the heat/energy
What happens if you add a catalyst to the system?
Nothing
What are the steps for solving an intermediate K problem?
- Calculate Q to determine the direction of the reaction.
- Make ICE table.
- Substitute into K and solve for x.
When solving a large K reaction should you let it go forward to completion?
Yes, this way it becomes a limiting reagent type problem.
What are the 6 strong acids?
HCl, HBr, HI, HNO3, HClO4, H2SO4
What is a polyprotic acid?
Acids that have several protons which can be donated.
What is the leveling effect?
The inability to tell the difference between the strength of strong acids in solvents like water or with a higher pH.
What is a buffer?
A solution that contains a considerable amount of a weak acid and its conjugate base.
They resist changes in pH when an acid or base is added to a solution.
How can a buffer be prepared?
Partial neutralization: The addition of a strong acid or base to one component of the buffer.
What is an equation for pKa?
-log[Ka]
What is buffer capacity?
The measure of the buffer’s ability to maintain pH.
What is buffer range?
The pH range where the buffer is effective.
What is Solubility?
The amount of solid that must be dissolved to produce a solution
What is precipitation?
When and how much solid will precipitate out of a solution.
What is the solubility product?
Ksp.
What is a saturated solution?
A solution with the maximum concentration of dissolved ions, with the solution in contact with extra undissolved solid.
When Q > Ksp?
The reaction proceeds towards reactants and precipitation is formed.
When Q < Ksp?
The reaction proceeds towards products and no precipitation is formed.
What is the common-ion effect?
It is the effect on an equilibrium involving a substance that ads an ion that is a part of the equilibrium.
When Q = Ksp?
The solution is saturated.
What are the 4 rules of solubility?
- Nitrate salts
- Alkali metals and ammonium salts
- Cl, Br, and I salts except with: Ag, Pb, and Hg2
- Sulfate salts except with: Sr, Ba, Pb, Hg2
What are the 4 rules of insolubility?
- Hydroxide salts
- Sulfide salts
- Carbonate salts
- Phosphate salts
all except with: group 1 and NH4 salts
Will basic salts be more soluble in acidic solutions?
Yes
What is a complex ion?
A central metal ion with several groups attached.
What is Kf?
The formation constant
How does adding H3O+ affect the solubility of anion of a weak acid?
It increases it solubility.