acids and bases Flashcards
bronsted acid
proton donor
strong acid
acid which ionises almost completely in an aqueous soln
eqm very far right
large Ka
HNO3, HCL,H2SO4
bronsted base
proton acceptor
weak acid
acid that only ionises partially in an aqueous soln
eqm lies far left
small ka
ionisation
reaction of a molecular substance with water to produce ions
dissociation
splitting of an ionic compound into its ions
polyprotic acids
able to donate more than one proton
dilute acid
small no. of moles in acid
strong base
base that dissociates almost completely in an aqueous soln
high Kb value
group 1 hydroxides
weak base
base that ionises partially in an aqueous soln
low Kb value
test for strong or weak base
conductivity
test for strong or weak base
conductivity
strength of an acid/base
independent of concentration of soln
concentrated acid/base
contains very large amount of acid/base than water in soln
has relatively more dissolved solute than a dilute soln
conjugate base pairs
1 product and 1 reactant, 1 H+ difference
stronger an acid/base- weaker its conjugate
conjugate base
substance formed when acid loses 1 proton
conjugate acid
substance formed when base gains one 1 proton
amphoterrpic/amphiprotic substance
substance that can act as either an acid or a base
H2O (water) , HCO3- (hydrocarbonate), HSO3- (hydrogen sulphate)
autoprolysis
auto-ionisation of water
self ionises to extremely limited extent
concentration of ions extremely low- eqm far left
Kw
1x10^-14 @25 degrees celcius
pH scale
measure of hydronium concentration in soln @25 degrees celcius
= -log[H3O+]
high number-low pH
small number-high pH
hydrolysis
reaction of an anion( from a salt) with water
occurs when salt of weak acid/base/both is dissolved in water causing water itself to decompose in rxn w ions of the salt
salt breaks down into pos + neg ions
water undergoes autoprolysis
conjugate ions of strong acids/bases and group 1 metals do NOT undergo hydrolysis
neutralisation
a chemical reaction in which an acid + a base react so that neither is in excess
forms salt and water
equivalence point should be the same as end point if done correctly.
standard solution
solution of known concentration
standard solution
solution of known concentration
acid-base titrations
acidic soln of known concentration added from a burette to a conical flask containing basic soln of unknwon concentration or vice versa, until end point is reached (indicator changes colour)
unknown concentration is calculated from readings from burrette
CHECK - titration point and equivalence point must be same
salt
substance in which the hydrogen of an acid has been replaced by a cation
salt
substance in which the hydrogen of an acid has been replaced by a cation
smaller Kb
weaker base
larger kb
stronger base
conjugate base
substance formed when acid loses 1 proton
conjugate base
substance formed when acid loses 1 proton
conjugate acid
substance formed when base gains 1 proton
neutral salt
made of strong acid + strong base
complete dissociation + ionisation
no hydrolysis will occur
no disruption to equal concentration of H3O+ and OH- ions in soln
salt has pH of 7
acidic salt
strong acid + weak base
acid ions will not undergo hydrolysis (conjugate of strong acid)
base undergoes hydrolysis forms product of weak base which will not dissociate complete
the formation of the weak base removes OH- ions from water
disruption to concentration of OH- and H3O+ ions in soln
water equilibrium shifts right to replace (OH-)
therefore the concentration of H3O+ ions increases
hence the salt is acidic , and the pH is less than 7
basic salt
weak acid + strong base
base does not undergo hydrolysis (dissociates completely)
therefore weak acid undergoes hydrolysis
product formed is a weak acid (won’t ionise completely)
formation of weak acid removes H+ ions , thus leading to a disruption in the concentration of H3O+ and OH- in soln.
The water equilibrium shifts right to replace H3O+ ions resulting in an increase in the concentration of [OH- ions]
therefore salt is basic , pH is larger than 7
acid-base titrations
titration - volumetric analysis
acidic solution of non-concentration ( standard solution) is added from a burette to a conical flask (containing basic solution of undone concentration measured in pipette in fixed volume) vice versa until endpoint is reached (indicator changes colour)
unknown [ ] is calculated from readings from burette
CHECK: titration end point should = equivalence point
equivalence point vs end point
equivalence- point in a titration where neither reactant is in excess
end point / point where indicator changes colour
acid + metal
salt + H2(g)
redox rxn
