Acids and Bases

Question 1

what is a Bronsted-Lowry acid?

Answer 1

a proton donor

Question 2

What is a bronzed-lowry base?

Answer 2

a proton acceptor

Question 3

what does an acid-base reaction involve?

Answer 3

the transfer of a single proton from one species to another
-a broasted Lowry acid will donate a proton to a bronzed Lowry base

Question 4

what are conjugate acid-base pairs?

Answer 4

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

Question 5

what is the equation for the autoprotolysis of water?

Answer 5

H2O (l) + H2O (l) ⇌ H3O+ (aq) + OH– (aq)

Question 6

what is the autoprotolysis of water?

Answer 6

Kw

Question 7

what is the value of Kw?

Answer 7

Kw = [H3O+][OH–] = 1.0 × 10-14 at 25*C

Question 8

why is Kw small?

Answer 8

because the autoprotolysis of water proceeds only to a small extent

Question 9

why is pure water neutral?

Answer 9

it contains equal concentrations of H3O+ and OH-
-for acidic aqueous solutions [H3O+]>[OH-]
-for basic aqueous solutions [H3O+]<[OH-]

Question 10

what is the relationship between [H3O+] and [OH-] in aqueous solutions

Answer 10

-ther eis an inverse relationships the concentration of one increases, the other must decrease to keep Kw constant

Question 11

how can [H3O+] be expressed in terms of pH?

Answer 11

pH=-log[H30+]

Question 12

what is pOH?

Answer 12

pOH is what is used to express [OH-]
pOH=-log[OH-] or
[OH-]=10-pOH

Question 13

what is a strong acid?

Answer 13

an acid that reacts completely with water to give quantitative formation of H3O+

Question 14

what is a weak acid?

Answer 14

an acid that reacts incompletely with water to form less than stoichiometric amounts of H3O+

Question 15

what is a strong base?

Answer 15

a base that reacts completely with water to give a quantitative formation of OH-

Question 16

what is a weak base?

Answer 16

a base that reacts incompletely with water to form less than stoichiometric amounts of OH-

Question 17

give examples of strong acids…

Answer 17

sulphuric acid-H2SO4
hydrochloric acid-HCl
Nitric acid-HNO3
Perchloric acid-HClO4
Hydrobromic acid-HBr
Hyroiodoic acid-Hl
Trifluoromethanesulfonic acid,CF3SO3H
Hexaflourophosphoric acid,HPF6

Question 18

give examples of strong bases?

Answer 18

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

Question 19

how do you work out Ka for weak acids?

Answer 19

Ka = [H3O+] [A-]/
[HA]

Question 20

what is the basicity constant?

Answer 20

for:B (aq) + H2O (l) ⇌ BH+ (aq) + OH– (aq)
Kb=Kb = [BH+] [OH-]/
[B]

Question 21

how is the strength of an acid determined?

Answer 21

-by its Ka value, the larger the Ka the stronger the acid
-the smaller the pKa,the stronger the acid

Question 22

how is the strength of a weak base determined?

Answer 22

-by its Kb value
-the larger the Kb,the stronger the base
-the smaller the pKb the stronger the base

Question 23

state the different acid and base calculations

Answer 23

Ka Kb = Kw
pKa + pKb = pKw
pKa=-log Ka
Ka=10-pKa
pKb=-log Kb
Kb=10-pKb