Acids and Bases Flashcards
what is a Bronsted-Lowry acid?
a proton donor
What is a bronzed-lowry base?
a proton acceptor
what does an acid-base reaction involve?
the transfer of a single proton from one species to another
-a broasted Lowry acid will donate a proton to a bronzed Lowry base
what are conjugate acid-base pairs?
for bronsted-lowry acid base reactions both the forward and reverse reactions are acid-base reactions
-there are always 2 sets of species on either side of the equation that differ by only one proton
what is the equation for the autoprotolysis of water?
H2O (l) + H2O (l) ⇌ H3O+ (aq) + OH– (aq)
what is the autoprotolysis of water?
Kw
what is the value of Kw?
Kw = [H3O+][OH–] = 1.0 × 10-14 at 25*C
why is Kw small?
because the autoprotolysis of water proceeds only to a small extent
why is pure water neutral?
it contains equal concentrations of H3O+ and OH-
-for acidic aqueous solutions [H3O+]>[OH-]
-for basic aqueous solutions [H3O+]<[OH-]
what is the relationship between [H3O+] and [OH-] in aqueous solutions
-there is an inverse relationships the concentration of one increases, the other must decrease to keep Kw constant
how can [H3O+] be expressed in terms of pH?
pH=-log[H30+]
what is pOH?
pOH is what is used to express [OH-]
pOH=-log[OH-] or
[OH-]=10-pOH
what is a strong acid?
an acid that reacts completely with water to give quantitative formation of H3O+
what is a weak acid?
an acid that reacts incompletely with water to form less than stoichiometric amounts of H3O+
what is a strong base?
a base that reacts completely with water to give a quantitative formation of OH-
what is a weak base?
a base that reacts incompletely with water to form less than stoichiometric amounts of OH-
give examples of strong acids…
sulphuric acid-H2SO4
hydrochloric acid-HCl
Nitric acid-HNO3
Perchloric acid-HClO4
Hydrobromic acid-HBr
Hyroiodoic acid-Hl
Trifluoromethanesulfonic acid,CF3SO3H
Hexaflourophosphoric acid,HPF6
give examples of strong bases?
lithium hydroxide,LiOH
Sodium hydroxide,NaOH
Potassium Hydroxide,KOH
Calcium Hydroxide,Ca(OH)2
Rubidium hydroxide,RbOH
Sodium methoxide,NaOCH3
Caesium hydroxide,CsOH
Barium Hydroxide,Ba(OH)2
how do you work out Ka for weak acids?
Ka = [H3O+] [A-]/
[HA]
what is the basicity constant?
for:B (aq) + H2O (l) ⇌ BH+ (aq) + OH– (aq)
Kb=Kb = [BH+] [OH-]/
[B]
how is the strength of an acid determined?
-by its Ka value, the larger the Ka the stronger the acid
-the smaller the pKa,the stronger the acid
how is the strength of a weak base determined?
-by its Kb value
-the larger the Kb,the stronger the base
-the smaller the pKb the stronger the base
state the different acid and base calculations
Ka Kb = Kw
pKa + pKb = pKw
pKa=-log Ka
Ka=10-pKa
pKb=-log Kb
Kb=10-pKb
write down the different formulas and examples
