Acid And Bases

Question 1

Brønsted-Lowry acids

Answer 1

Proton donor

Question 2

Brønsted-Lowry base

Answer 2

Proton acceptor

Question 3

Conjugate acid base pair

Answer 3

HCl and Cl-
HCl releases a proton to form Cl-
On reverse Cl- reacts with proton to form HCl

Question 4

Hydronium ion

Answer 4

H3O+
Water accepts proton (base) forming a conjugate acid

Question 5

Monobasic dibasic & tribasic

Answer 5

Number of hydrogen ions in the acid

Question 6

Acid +metal

Answer 6

Salt + hydrogen

Question 7

Acid + carbonate

Answer 7

Salt+ water+ CO2

Question 8

Acid + base

Answer 8

Salt+ water

Question 9

pH relationship w [H+]

Answer 9

pH= -log[H+]
H+ = 10-pH

Question 10

Calculating pH of strong acid

Answer 10

H+ conc= HA conc
pH calculated directly from conc of acid
- log (conc of acid)

Question 11

Ka

Answer 11

Acid dissociation constant
= [H+][A-]/[HA]
Stronger the acid the larger the Ka value lower the pH

Question 12

pKa

Answer 12

-logKa
Inverse= 10^-pKa
Stronger the acid the lower the pKa higher the pH

Question 13

pH of weak acids

Answer 13

Weak acid= equilibrium
Calc conc at equilibriums
Use Ka
H+ = squat root of (Ka x [HA])
-log ans

Question 14

Approximation using Ka to calculate ph of weak acid

Answer 14

•[H+]=[A-]
Neglects H+ dissociation of water
•[HA eq] = [HA start]neglect decrease in conc

Question 15

Kw

Answer 15

[H+][OH-]
Ionic product of water
=1 x 10^-14

Question 16

Buffer

Answer 16

Minimises pH changes when small amounts of acid/ alkali are added
Contain an weak acid and it’s conjugate base

Question 17

Addition of acid -buffer action

Answer 17

H+ conc increases
React w conjugate base of buffer
Equilibrium shifts to the left removing H+ ions

Question 18

Addition of alkali - buffer action

Answer 18

OH- conc increases
H+ react forming water
HA dissociates to replenish the H+ ions by shifting equil to the right

Question 19

Calculating pH of buffer sol

Answer 19

H+= Ka x HA/A
-log ans

Question 20

Carbonic acid hydrogen carbonate buffer system in the blood

Answer 20

Addition acid react w HCO3- equil shifts to left
Addition alkali OH- reacts w H+ H2CO3 dissociates to replenish H+ ions

Question 21

pH titration curve

Answer 21

Base added acid in excess once slightly
As vertical section approach pH increase starts to quicken acid used up more
Rapidly increase vertical section

Question 22

Equivalence point

Answer 22

Centre of the vertical section of the pH titration curve
Volume of solution that exactly reacts with vol of other solution

Question 23

End point

Answer 23

Weak acid which has a different colour to its conjugate base - end point when in between is formed

Question 24

Indicator colour changes

Answer 24

OH- react with H+ weak acid colour changes and equil shifts to the right change colour
H+ ions added A - react orange at end point and to red when equil has shifted to the left

Question 25

Choosing correct indicator

Answer 25

Indicator range must coincide w vertical section of pH titration curve end point and equivalence point coincide