Acids and Bases Flashcards
Bronsted- Lowry Acid
A proton donator (H+). must have a H atom that it can lose as H+ ion
Bronsted- Lowry Base
A proton acceptor (H+). Must have a non-bonding pair of electrons that it can bind the H+ ion.
Arrhenius Acid
Produces H+ ions in in solution. Increases the [H+] in water
Arrhenius Base
Produces OH- ions in solution. increases the [OH] in solution
Amphoteric/ Amphiprotic
a species that can act as an acid and a base.
Strong Acid
completely dissociates in water. These are also strong electrolytes existing in aqueous solutions entirely as ions.
- HCl- hydrochloric acid
- HBr- hydrobromic acid
- HI- hydroiodic acid
- HNO3- nitric acid
- HClO4- perchloric acid
- H2SO4- sulfuric acid
- HClO3- chloric acid
strong bases
Strong electrolytes in aquoes solutions.
1. LiOH- lithium hydroxide
2. NaOH- sodium hydroxide
3. KOH- potassium hydroxide
4. RbOH- rubium hydroxide
5. CsOH - cesium hydroxide
6. Ca(OH)2- calcium hydroxide
7. Sr(OH)2- strontium hydroxide
8. Ba(OH)2 - barium hydroxide
The strongest acids/bases have the…
… weakest conjugate base/acids (kw)
Kw
ion product constant of water.
kw = 1,0 x 10^ -14
ka x kb = kw
pH/ pOH
pH = -log [H3O+]
pOH = -log [OH-]
pH + pOH = 14
pKa / pKb
pKa = =log [Ka]
pKb = -log [Kb]
the species with more protons…
is the acid.
Doubling the [of a weak acid]…
does not double the [H30+]
the higher the [ ] the lower the extent of ionization.
the greater the ka/ kb value…
the stronger the acid/ base ( hence pka/ pkb is smaller)
the position of equilibrium favours…
the transfer of the proton from the stronger acid to the stronger base to form the weaker acid and the weaker base.
the equilibrium mixture contains more…
weaker acid/ base and less stronger acid/base.
Weak Acids
only partially ionize in solution.
1. HF - hydroflouric acid
2. HNO2- nitrous acid
3. C6H5COOH - benzoic acid
4. CH3COOH- acetic acid
5. HClO- hypochlorous acid
6.HOC6H5- phenol acid
weak bases
only partially ionize in solution.
1. NH3 - ammonia
2. C5H5N- pyridine
3. C03- carbonate ion
4. HS- hydrosulfide ion
5. ClO -hypochlorite ion
6. H2NOH - hydroxylamine
7. NH2CH3 - methylamine
Percent ionization
% = (concentrations ionized ÷ original concentration) x 100
the stronger the acid…
the greater the percent ionization
polyprotic acid
An acid that can donate more than one proton (H+)
What effect will the Anion that is the conjugate base of a strong acid have on the pH?
will not affect the pH as it is a spectator ion
what effect will the Anion of a weak acid have on the pH?
it will cause an increase in pH.
What effect will a cation that is the conjugate acid of a weak base have on the pH?
it will decrease the pH.
what effect does cations of strong Arrhenius bases have on the pH?
these will not affect the pH as they are spectator ions.
these include cations of group 1A and heavier group 2A cations ( Ca; Sr; Ba).
what is the common ion effect?
whenever a weak electrolyte and a strong electrolyte contain a common ion, the weak electrolyte ionizes less than it would if it were alone in solution. This is important in buffer solutions.
what do we need in order to create a common ion?
a weak acid and a soluble salt of that acid.
salt
substance produces in an acid and base reaction.
are generally strong electrolytes.
what happens when you add a strong electrolyte to a weak acid? according to Le chateliers principle
- An increase in the [ of weak acid]
- this causes equilibrium to shift to the left
- the H+ ions are used up and there is a decreases in the [H+] ions.
- pH increases (making it less acidic) as it ionizes less.
Buffer solutions
*solutions that contain a weak conjugate acid-base pair.
*It resists drastic changes in the pH when small amounts of strong acids or bases are added. Because it has both an acid to neutralize OH ions and a base to neutralize H ions
* keep the pH nearly constant.
how are buffers prepared?
by mixing a weak acid or a weak base to a salt of that acid or base.
Calculations in pH of a buffer we use…
- Common ion method with ICE table and ka constant
- Henderson- hasselbalch equation
pH = pka + log [base] ÷[ Acid]
as the [weak acid] increases what happens to the equilibrium concentration oh [H+] and the % ionization?
the equilibrium concentration oh H+ increases, however the % ionization decreases as the concentration increases
how is pH affected with an anion that is the conjugate base of a weak acid
it will cause an increase in the pH
how is pH affected with an anion that is the conjugate base of a strong acid?
will not affect the pH ( they are spectator ions)
how is pH affected by the cation that is the conjugate acid of a weak base?
will cause a decrease in the PH
how does the cations of group 1A and heavier group 2A affect pH?
it will not affect the pH.
Methyl red
pH= 4-6
red to yellow
Bromothymol blue
pH= 6 -8
yellow to blue
Phenolphthalein
pH = 8-10
colourless to pink/magenta
