UNIT 1 Section 10 - Acids, Bases and pH

Question 1

define a bronsted lowry acid

Answer 1

proton donor

Question 2

define a bronsted lowry base

Answer 2

proton acceptor

Question 3

write an equation for the ionisation of water to from H+ ions

Answer 3

H2O <—-> H+ + OH-

Question 4

write an equation for the ionisation of water to produce a hydroxonium ion

Answer 4

2H2O <—-> H3O+ + OH-

Question 5

what is the equation for Kw

Answer 5

Kw= [H+][OH-]

Question 6

what is the value of Kw at 289K

Answer 6

1x10-14

Question 7

what physical factors affect the value of kw and how

Answer 7

temperature

if the temperature is increased the equilibrium shifts to the right so Kw increases and the pH decreases

Question 8

why is pure water still neutral is the pH isnt 7

Answer 8

the concentration of H+ is still equal to the concentration of OH-

Question 9

what is the expression for pH

Answer 9

pH=-log10[H+]

Question 10

if two solutions have a difference of 1 what is the difference in [H+]

Answer 10

a factor of 10

Question 11

what is the expression of [H+] from pH

Answer 11

[H+] = 10-pH

Question 12

what is the difference when finding [H+] from the concentration of diprotic and triprotic acids

Answer 12

need to multiply the concentration of the acid by the number of protons

Question 13

define the term strong acid

Answer 13

one which fully dissociates in water

Question 14

define the term strong base

Answer 14

one which fully dissociates in water

Question 15

what is a weak acid and base

Answer 15

weak acids and bases do not fully dissociate in water and only partially dissociate into their ions

Question 16

give examples of strong acids

Answer 16

HCL, H2SO4,H3PO4

Question 17

give some examples of strong bases

Answer 17

NaOH, CaCO3, Na2CO3

Question 18

give some examples of weak acids

Answer 18

CH3COOH

Question 19

give an example of a weak base

Answer 19

NH3

Question 20

what is the expression for Ka

Answer 20

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

Question 21

what is a titration

Answer 21

teh addition of an acid or base of a known concentration to an unknown base or acid to determine the concentration of the unknown acid or base

Question 22

define the term equivalence point

Answer 22

the point where the exact volume of base has been added to neutralise the acid or vice versa

Question 23

what generally happens to the pH of a solution around the equivalence point

Answer 23

there is a large and rapid change in pH except in weak acid and weak base titration

Question 24

what is the end point

Answer 24

when the indicator just changes colour

Question 25

what are the properites of a good indicator for a reaction

Answer 25

sharp colour change end point must be the same as the equivalence point distinct colour change

Question 26

what indicator would you use for a strong acid-base titration

Answer 26

Phenolphthalein

Question 27

what indicator would you use for a strong-acid weak base titration

Answer 27

methyl orange

Question 28

what indicator would you use for a strong base-weak acid titration

Answer 28

phenolphthalein

Question 29

what indicator would you use from a weak acid and weak base titration

Answer 29

neither work

Question 30

what colour is methyl orange in and acid and colour in an alkali and what pH does it change

Answer 30

red in acid yellow in alkali 4-5

Question 31

what colour is phenolphthalein in and acid and colour in an alkali and what pH does it change

Answer 31

colourless in acid red in alkali 9-10

Question 32

what is the half neutralisation point

Answer 32

when the volume = half the volume that has been added at the equivalence point

Question 33

draw a strong acid base graph

Answer 33

refer to booklet

Question 34

draw a strong acid weak base graph

Answer 34

refer to booklet

Question 35

draw a weak acid strong base graph

Answer 35

refer to booklet

Question 36

draw a weak acid and weak base graph

Answer 36

refer to booklet