Ch 9 Acid Base Buffers Flashcards
What is an Acid?
Substance that yields H+ when dissolved in Water. Simplified: A proton, H+, donor.
An acid that donates one proton is termed?
Monoprotic
An acid that donates two protons is termed?
Diprotic
An acid that donoates three protons is termed?
Triprotic
How do strong acids behave in water?
Fully dissociate, one-directional rxn, into hydronium ion (H3O+) and conjugate base (reactant minus a H+)
How do weak acids behave in water?
Do NOT fully dissociate - create an equilibrium rxn.
What is the relationship between pH and [H+] concentration?
inverse relationship. As pH goes up, [H+] goes down.
As pH goes down, [H+] goes up.
The larger the [H+] the more ____ the solution
Acidic
What is a Base?
A base is a proton, H+, Acceptor.
Concentration of Base is measured by?
[OH-]
As [OH-] goes up, what is happening to the solution?
More alkaline aka Basic Bitch
what is the relationship between,
pOH and [OH-]
Inversely proportion. As [OH-] increases, pOH decreases.
What is the relationship between pH and pOH
Low pH = High pOH
High pH = Low pOH
13 on the pOH scale means the solution is basic or acidic?
ACIDIC
2 on the pOH scale means the solution is basic or acidic?
BASIC
As [OH-] goes up, what happens to pOH, pH, and [H+]?
pOH: goes down, a smaller number which means more basic
pH: goes up, bugger number, which means more basic
pH + pOH always equals?
14
An acid, once losing/donating its proton, becomes what on the product side?
Conjugate Base (of the acid)
A base, once gaining/accepting a proton, becomes what on the product side?
Conjugate Acid (of the base)
what is the pH equation?
pH = -log^[H+]
What is the pH of a solution with a [H+] concentration of 1x10^-7?
- Just take the absolute value of the exponent!
What is the difference in [H+] of a pH of 6 compared to 8?
pH of 6 has 100x more H+
Each 1 change in pH is equal to 10x the change in [H+]
Which is more acidic:
[H+] = 1x10^-5
[H+] = 1 x 10^-7
1x10^-5 because the exponent is 5, this is equal to the pH. 5 is less than 7, meaning it is more acidic on the pH scale.
What is an amphoteric substance?
It can act as an acid or base, depending on the situation. Water is the primary example/
Stronger or weaker have a higher Ka
Stronger Acids
What is Kw?
Equilibrium constant for water. 1 x 10^-14
Which rxn would give you relatively more product? A strong acid or weak acid?
Strong because it will not reverse back into the reactant
Which has a larger Ka, strong or weak acids? Why?
Strong Acids have larger Ka.
Because Ka= [product] / [reactant] , strong acids fully dissociate, there will be more product.
equation for pKa
pKa = -logKa
What are 5 strong acids
H2SO4, HI, HBr, HCL, HNO3
What does Ka represent?
The strength of the acid, meaning how likely/much the acid wants to donate/loss its proton(s).
When reviewing two weak acids, how do you determine which one is stronger?
Look at Ka. Stronger weak acid will have the large Ka.
For polyprotic acids, which proton is donated more quickly/strongly?
The first proton donated. Review triprotic phosphoric acid.
Regarding relationships between an acid and its conjugate base. The stronger the acid, the _______ its conjugate base.
Weaker
Regarding relationships between a base and its conjugate acid. The stronger the base, the _______ its conjugate acid.
weaker
What is the relationship between Ka and Pka?
Inverse. Higher Ka , lower pKa
(same as base, Kb and pKb)
pKa +pKb =
14
if given a concentration, M, of a strong acid what is your concentration of the conjugate acid?
Same concentration of reactant strong acid
if given a concentration, M, of a strong base what is your concentration of the conjugate base?
Same concentration of reactant strong base
If your Ka or Kb value is high, (greater than 10^3) what direction will your reaction favor?
Product conc > reactant conc. So, a forward reaction is favored. Equilibrium lies to the right.
If your Ka or Kb value is low (less than 10^-3), what direction will your reaction favor?
Reactant conc > product conc. So, a reverse reaction is favored. equilibrium lies to the left
If your K value is about 1, what direction will your reaction favor?
Neither direction is favored. The reaction proceeds halfway. Conc of reactants ~ Conc of products
What are some strong bases?
LiOH, KOH, NaOH, Ba(OH)2
Why isn’t Mg(OH)2 a strong base?
its insoluble
The stronger the acid, the ______ its conjugate base.
Weaker. The conjugate base is “weak” if it is less likely to accept the proton it donated. Such is the case for a strong acid-conjugate base pair.
The stronger the base, the _____ its conjugate acid.
Weaker. The OH- is less likely to donate the hydrogen it accepted.
Does the conjugate base of a weak acid have base strength or not?
Does. It is capable of accepting the proton it initially donated, reversing the reaction.
The reaction equilibirum always favors the formation of a?
weaker acid
A change in 1 unit pH is equal to a ___ fold change in H+
10x
pKw = ?
14
-log(Kw)
pKa + pKb = ?
14
IMPORTANT CONCEPT
What is pKa relative to pH?
pKa is the pH at which 50% of the compound in solution is ionized and 50% of the compound is unionized.
AKA: half acid, half conjugate base
Why is NaCl neutral pH when dissolved in water?
Fully dissociates but does not react with water. Because water is neutral pH, and NaCl does not react, the pH of solution remains neutral.
An Alpha plot demonstrates the ratio of?
The % ratio of ACID to Conjugate Base.
