6.3 Quantitative Analysis Flashcards
(33 cards)
what is ionisation
chemical change of molecule to become ion
most naturally occurring acids are organic that contains ___ group
COOH (carboxyl)
equilibrium of strong acid equation
right (ionises completely)
equilibrium of weak acid equation
left (majority still molecules)
polyprotic acids…
have more than 2 dissociable protons that undergo stepwise ionisation
multiple hydrogen ions in the acid
degree of ionisation =
[H3O+] / [HA] x 100%
ionisation constant equation
Ka = [H3O+][A-] / [HA]
what is ionisation constant
strength of an acid
a strong acid has Ka…
a weak acid has Ka…
strong, Ka >1
weak, Ka <0.01
relative strength of acids equation
pKa = -log10 (Ka)
lower pKa means…
higher pKa means…
lower pKa = stronger acid
higher pKa = weaker acid
(basically inverted Ka)
which hydrogen ion does formic acid donate HCOOH
from the back. HCOO-
strength vs concentration
strength (strong or weak) is DEGREE OF IONISATION
concentration (concentrated or dilute) is relative to AMT OF WATER PRESENT
electrical conductivity of acids and bases
strong acids and strong bases make good electrolytes
4 strong acids
HCl, HBr, HNO3, H2SO4
the more dilute a weak acid, the …… the %ionisation
greater
strong bases…
dissociate completely
base dissociation constant Kb equation
Kb = [BH+] [OH-] / [B]
(ionic product of water) Kw =
Ka x Kb
self ionisation of water equilibrium
2H2O <> H3O+ + OH-
self ionisation of water constant
Kw = [H3O+] [OH-]
what is hydrolysis
when solid reacts with water and alters pH of solution
as temperature goes down, pH of neutral water …
pH goes down (more acidic)
STRONG acid + STRONG base =
NEUTRAL salt solution
pH = 7
