Acid/Base Equilibrium Flashcards
What is Kc?
- The equilibrium constant
- The ratio between products and reactants
What is Kw? What is its value?
Kw is the equilibrium constant of water at standard room temperature. It’s value is 1.00 x 10^14.
When does dynamic equilibrium occur?
When the rate of the forward reaction is equal to the rate of the reverse reaction.
- Occurs in a reversible reaction
What happens to the micro and macroscopic properties of a reaction at equilibrium?
The macroscopic properties of the reaction(concentration, color, pressure, things you measure and observe with your eye) stop changing. Microscopic properties can still change(LDF, bonds breaking and forming, reactions still occurring)
What is static equilibrium? Can a reaction ever be in static equilibrium?
When macroscopic and microscopic properties stop changing
- Concentration gradient still exists
What are the requirements to reach chemical equilibrium? What are some common equilibria?
A reaction must be reversible and the system needs to be closed or isolated for dynamic equilibrium to be established. Some common equilibria are saturated solutions and phase changes at mp or bp.
What is the only thing that changes the value of Kc in a reaction?
A change in temperature
What is the rule with solids and liquids in the equilibrium expression?
Solids and PURE liquids(only one liquid in the whole reaction) go in as 1.
For the equilibrium expression to work, the reaction must be _________(1). The equation should be balanced with the ________________(2)
(1) net ionic
(2) Lowest whole number ratio
What does the size of Kc indicate about the reaction?
- If Kc»1 : Products are favoured and more products are being made
-Kc = 1 : Reactants and products are equally favoured
-Kc«1 : Reactants are favoured
What are the two ways to determine which way a reaction will shift?
- Are there any zero concentrations? The reaction must shift towards that side because there can not be zero concentration
- Use Q, the reaction quotient: Q has the same formula as Kc but the concentrations inputted are at any point in the reaction.
- If Q < K : More products are needed to make Q bigger so the reaction shifts towards the products - If Q = K : Reaction is at equilibrium - If Q > K : More reactants are needed to make Q smaller so the reaction shifts towards the reactants
When are ice tables used?
When dealing with weak acids and bases
The equilibrium constant for the forward and reverse reaction are __________(1) to each other.
(1) inverse
What is Le Chatelier’s principle?
When a system at equilibrium is stressed, the equilibrium will shift in order to remove the stress
What is the law of mass action?
Q vs K stuff
What does “stress” mean?
Something that affects the reaction rate
What effect does temperature have on a reaction?
An increase in temperature speed up the endothermic reaction rate more than the exothermic.
A decrease in temperature speeds up the exothermic reaction more than the endothermic
What effect does pressure have on a reaction?
Increased volume means more room for more moles; reaction shifts towards the side that has more moles
What effect does concentration have on the reaction?
If a substance is added, the equilibrium will shift away from that side. If a substance is removed, the equilibrium will shift towards that side.
What effect does a catalyst have on a reaction?
Both rates are sped up equally so no change in equilibrium position
What are 5 characteristics of acids?
- Turns litmus paper red
- H+ containing
- pH<7
- React with metal to make bubbles
- Can taster sour
What are 5 characteristics of bases?
- Turns litmus paper blue
- OH containing
- pH>7
- Don’t react with metal to make bubbles
- Slippery/soapy
What characteristic is shared by bases and acids?
Both are electrically conductive
According to the Bronstead-Lowry, what do acids and bases do in a reaction?
Acids donate and bases accept
Acids have hydronium, bases have OH
Whatever the acid donates to is the conjugate base.
What does amphiprotic mean?
Can act like an acid or a base depending on what it is mixed with. For something to be amphiprotic, it must appear in both the acid and conjugate base columns on the chart
What is hydrolysis?
Using water to break something apart
What is a buffer?
Made by mixing a wet acid and its conjugate base in significant amounts. A buffer resists changes to pH.
What is an indicator?
Indicators change colour depending on the pH of the solution they are added to
What is a conjugate acid/base pair?
The acid and what base it would be if it donated a hydrogen
Conjugate bases of strong acids are “fake bases” meaning ___________________________(1).
they don’t behave like a base in water
The concentrations used to calculate Kc must be _____________(1).
equilibrium concentrations(not intial).
What effect does dilution of water have on an equilibrium system?
More dilution, more volume, reaction shifts towards side with more moles.
What is the difference between strength and concentration?
Strength: How well something ionizes(ie. 100% or not)
Concentration: mols/L
What is an inert gas? What effect does adding an inert gas have on the equilibrium of a reaction?
Inert gases: Noble gases and N2
No effect on equilibrium position.
Why is HSO4 not amphiprotic in water?
HSO4 is too weak to act as a base IN WATER. Strong acids ionize 100% which means that the reverse reaction is not occurring. As a result, the conjugate base is not formed. Conjugate bases of strong acids are fake bases meaning they don’t behave like a base in water.
Weak acids and bases _________(1) ionize in water. Strong acids and bases _____________(2) ionize in water.
(1) partially
(2) fully
Acidic and basic properties depend on __________________?
- How strong the acid or base is
- How concentrated the acid or base is
What part is acidic in organic acids?
The only H that is acidic is the H that is attached to the OH
What are the three options/outcomes for hydrolysis?
- The compound makes an ion that is acidic or basic or all neutral
- The products are one acidic and one basic. If Ka> Kb more acidic products formed so solution would be acidic.
- An ion is amphiprotic: Compare Ka and Kb of the same substance.
Would an acidic solution react with a metal to make bubbles?
yes
