Chapter 16 - Acid/Base Flashcards
Arrhenius base definition
A substance that when dissolves in water increases concentration of hydroxide ions
Acids according to Arrhenius
An acid is a substance that when dissolved in water, increases concentration of hydrogen ions
Bronsted Lowry acid definition
A proton donor
Bronsted Lowry base definition
A proton acceptor
Amphiprotic
Can be either base or acid
HCO3-
HSO4-
H2O
What happens when an acid dissolves in water?
Water acts as a B-L base and yoinks a proton H+ from the acid.
The conjugate base of the acid and hydronium ion are formed
Conjugate base
Of an acid (remove the H)
Acid and conjugate base strength
Strong acid are completely dissociated in water (conjugate bases are weak)
Weak acids only dissociated partially in water (conjugate bases are weak but stronger than those for strong acids)
Substances with negligible acidity
Do not dissociate in water
Conjugate bases are super strong
OH-
H2
CH4
Equilibrium favors which side of the reaction?
The reaction that moves the proton to the stronger base
Reactants (K»1)
Products (K«1)
Autoionization of water
Few molecules act as bases and few act as acids
Ion product constant
Kc = [H3O+][OH-]
Which also equals Kw
At 25 celcius Kw is 1.0x10^-14
pH
-log[H3O+] which is -log[H+]
In water the concentration of hydroxide and hydronium are equal
pH of acid
Less than seven
More hydronium than water
pH of base
More the seven
Less hydronium than water
pH + pOH
=pKw = 14
How do we measure pH?
Litmus paper (red turns blue it is above eight and blue turns red it is below five)
Indicator
pH meter measures voltage
SEVEN STRONG ACIDS
HCl HBr HI HNO3 H2SO4 HClO3 HClO4
Strong electrolytes exist totally as ions in aqueous solution
For monoprotic strong acids the concentration of the acid equals the concentration of hydronium
Strong bases
Soluble hydroxides
Alkali metal and alkaline earth metal hydroxides
Dissociate completely in aqueous solution
Dissociation constants
Kc= concentration of hydronium times concentration of acid’s conjugate base divided by acid
Also called Ka
Ka and Kb relating to strength
The greater the Ka the stronger the acid
Greater Kb the more basic
Percent ionization
Concentration of hydronium at equilibrium divided by initial concentration of acid
X100%
Polyprotic acids
Have more than one acidic proton
HxCxOx or HxPO4 or HxSOx
Ka and Kb
Ka x Kb = Kw
Lewis acids
Electron pair acceptors
Atoms with an empty valence orbital can be Lewis acids
Lewis bases
Electron pair donors
Any B-L base is a Lewis base
Can interact with things other than protons
Factors affecting acid strength
More polar or more weaker the more acidic
Increases left to right and top to bottom
Greater charge and smaller size means more acidic
Carboxylic
Resonance in conjugate base of carboxylic acids stabilizes the base and makes the conjugate more acidic
COOH
Hydrolysis
When ions of salt react with water to generate hydroxide and hydrogen ions
pH of salt solutions. If neither anion and cation react with water
Neutral. Anion is a CB of a strong acid AND the cation is either 1A or heavy 2A
pH of salt solution when anion reacts only
Basic. Anion is CB of weak acid and cation is 1A or heavy 2A
pH when cation reacts
Acid. Cation is CA of a weak base or with charge of 2+ or greater
NH4NO3
Oxyacids
OH to Y
The more electronegative Y is the more acidic the acid
Acidity increases with # of oxygens
