Chapter 4 - Acids and Redox (MODULE 2)

Question 1

what is released when acids dissolve in water

Answer 1

H+ ions

Question 2

What is a strong acid

Answer 2

one which releases all its H+ ions into solution and completely dissociates in aqueous solution

Question 3

What is a weak acid

Answer 3

one which doesn’t release all its H+ ions into solution and partially dissociates in aqueous solution

Question 4

WHat are some examples of strong acids

Answer 4

HCl. H2SO4, HNO3

Question 5

What are some examples of weak acids

Answer 5

ethanoic acid, most organic acids

Question 6

What sign is used to indicate the forward reaction is incomplete

Answer 6

equilibrium arrow

Question 7

What are some general examples of bases

Answer 7

metal oxides, metal hydroxides, metal carbonates and ammonia

Question 8

what is the reaction between an acid and base called
- what is always produced

Answer 8

neutralisation
- a salt

Question 9

What is an alkali

Answer 9

a base that dissolves in water releasing OH- ions into solution

Question 10

How is a salt formed in neutralisation

Answer 10

H+ ion in acid is replaced by metal or ammonium ions from base

Question 11

What are the general products for acid + metal

Answer 11

salt + hydrogen

Question 12

What are the general products for acid + metal oxide

Answer 12

salt + water

Question 13

What are the general products for acid + metal hydroxide

Answer 13

salt + water

Question 14

What are the general products for acid + metal carbonate

Answer 14

salt + water + carbon dioxide

Question 15

What is a titration used for

Answer 15

accurately measuring the volume of one solution that reacts exactly with another solution

Question 16

What are the 3 main uses of titrations

Answer 16

• finding the concentration of a solution
• identification of unknown chemicals
• finding the purity of a substance

Question 17

What is a standard solution

Answer 17

a solution of known concentration

Question 18

What are standard solutions made in

Answer 18

volumetric flasks

Question 19

what are the typical tolerances of:

• 100cm^3
• 250cm^3
  volumetric flasks

Answer 19

• ±0.20cm^3
• ±0.30cm^3

Question 20

in an acid - base titration, what measuring apparatus is used

Answer 20

pipette and burette

Question 21

what are the typical tolerances of

• 10cm^3 pipette
• 25cm^3 pipette
• 50cm^3 burette

Answer 21

• ± 0.04cm^3
• ± 0.06cm^3
• ± 0.10cm^3

Question 22

How are burettes always read

Answer 22

• from the bottom of the meniscus
• to the nearest half-division (0.05cm^3)
• always 2 d.p.

Question 23

How do you calculate the mean titre

Answer 23

work out the mean of 2 concordant titres

Question 24

what are concordant titres

Answer 24

titres within 0.10cm^3 of each other

Question 25

What is the oxidation number of elements

Answer 25

0

Question 26

What is the usual oxidation number for - O - H - F - group 1 - Group 2 - Halides

Answer 26

: -2 : +1 : -1 : +1 : +2 : -1

Question 27

What are the oxidation numbers for - H in metal Hydrides - O in peroxides - O bonded to F

Answer 27

- -1 - -1 - +2

Question 28

What is the sum of oxidation numbers in a compound equal to

Answer 28

the overall charge

Question 29

what does the roman numeral in the names of compounds show

Answer 29

the oxidation number of the element without a sign

Question 30

what is the charge of N in - NO2 (-) - NO3 (-)

Answer 30

- nitrate (III) (+3) - nitrate (V) (+5)

Question 31

Given that roman numerals are omitted for more common ions, what is the formula of what is called - nitrate - sulfate

Answer 31

- NO3 (-) - SO4 (2-)

Question 32

What is oxidation in terms of electrons

Answer 32

the loss of electrons

Question 33

What is reduction in terms of electrons

Answer 33

the gain of electrons

Question 34

What is oxidation in terms of oxidation number

Answer 34

an increase in oxidation number

Question 35

What is reduction in terms of oxidation number

Answer 35

a decrease in oxidation number

Question 36

what is a redox reaction

Answer 36

one where both reduction and oxidation occurs