C4+C10 Acids and Bases

Question 1

what are ACIDS?

what color do acids turn litmus paper to?

Answer 1

compounds that break into H+ ions

turn litmus paper RED

Question 2

what are BASES?

what color do bases turn litmus paper to?

Answer 2

compounds that break into OH- ions

turn litmus paper BLUE

Question 3

what are ALKALIS?

Answer 3

soluble bases

Question 4

what is the pH scale?

Answer 4

a measure of the number of H+ ions in a solution

• lots of H+ means low pH
• lots of OH- means high pH

Question 5

acid + metal = ?

Answer 5

salt + hydrogen

Question 6

acid + metal oxide = ?

Answer 6

salt + water

Question 7

acid + metal hydroxide = ?

Answer 7

salt + water

Question 8

acid + metal carbonate = ?

Answer 8

salt + water + carbon dioxide

Question 9

acid + alkali = ?

Answer 9

salt + water

Question 10

how are salts formed?

Answer 10

when a base neutralizes an acid

Question 11

what are the three methods of SALT PREPARATION?

what are the REACTANTS and PRODUCTS of each?

Answer 11

EXCESS:
insoluble base + acid = soluble salt + water

TITRATION:
soluble base + acid = soluble salt + water

PRECIPITATION:
soluble salt + soluble salt = insoluble salt + soluble salt

Question 12

what are the steps of the EXCESS method?

draw a diagram and explain step by step (6)

Answer 12

1. warm acid
2. add EXCESS INSOLUBLE BASE
3. FILTER mixture
4. HEAT (evaporating dish over bunsen burner) to evaporate water → CRYSTALS form
5. leave to cool
6. FILTER to get crystal and dry the crystals

Question 13

EXCESS METHOD:

1. why is acid warmed?
2. why is an excess of insoluble base used?
3. why do you filter the mixture?

Answer 13

1. to speed up reaction
2. so all acid react
3. remove excess insoluble base

Question 14

what are the steps of the TITRATION method?

draw a diagram and explain step by step (6)

Answer 14

1. ALKALI+INDICATOR in the conical flask
2. add ACID to alkali (using burette)
3. note the VOLUME OF ACID added

—– repeat without indicator —–

4. HEAT (evaporating dish over bunsen burner) to evaporate water → CRYSTALS form
5. leave to cool
6. FILTER to get crystal and DRY the crystals

Question 15

TITRATION METHOD:

why do you use an indicator first, then repeated without the indicator?

Answer 15

to know the volume of acid needed to neutralize the solution

Question 16

what are the steps of the PRECIPITATION method? (4)

Answer 16

• MIX the two soluble salts
• FILTER to get precipitate
• WASH the precipitate with distilled water
• leave to DRY

Question 17

define concentration of the solution

Answer 17

the number of moles per dm3

Question 18

how to convert dm3 to cm3?

Answer 18

1 dm3 = 1000 cm3

Question 19

how to convert moles into grams?

Answer 19

(mol/dm3) x (molar mass)

Question 20

what are some SAFETY PRECAUTIONS during salt preparation?

Answer 20

safety goggles
gloves to avoid contact (acid/alkali are irritating)
long hair tied up (fire)

Question 21

revise the DIAGRAM+APPARATUS of salt preparations in notes!!

Answer 21

check notes :)

Question 22

what salts are ALWAYS SOLUBLE?

Answer 22

SPA - sodium, potassium, ammonium

Nitrates

Question 23

what salts are SOLUBLE most of the time?

what are the exceptions?

Answer 23

Sulfates
(except with Pb, Hg, Ag, Ca, Sr, Ba)

Group 7 
(except with Pb, Hg, Ag)

Question 24

what salts are INSOLUBLE most of the time?

what are the exceptions?

Answer 24

CO3
OH
(except when with SPA)

Question 25

how to calculate the CONCENTRATION OF SOLUTION?

Answer 25

Concentration = #Moles / Volume

Question 26

how to calculate #MOLES?

Answer 26

Moles = Mass / Molar Mass

Question 27

LIMESTONE → LIME

• how? what’s this method called?
• diagram?
• word equation?
• observations?

Answer 27

• HEAT limestone for 10 mins
• THERMAL DECOMPOSITION
• CaCO3 → CaO (lime) + CO2
• CaCO3 chip turns black then white

Question 28

LIME → LIMEWATER / SLAKE SLIME

• how?
• word equation?
• observations?

Answer 28

• add WATER to heated limestone
• CaO + H2O → Ca(OH)2
• EXOTHERMIC rxn, WATER HISSES

Question 29

similarity and difference between limewater and slake lime?

Answer 29

both Ca(OH)2
slake lime: as solid
limewater: as solution

Question 30

LIMEWATER → CaCO3

• how?
• word equation?
• observations?

Answer 30

• BLOW BUBBLES through solution
• Ca(OH)2 + CO2 → CaCO3 + H2O
• limewater becomes CLOUDY (insoluble CaCO3 forms)

Question 31

uses of LIMESTONE

Answer 31

NEUTRALIZE acidic soil and industrial waste

Question 32

source of CO2

Answer 32

burning fossil fuels, respiration

Question 33

source of SO2

Answer 33

burning fossil fuels

Question 34

source of nitrogen oxides (NO, NO2 N2O)

Answer 34

vehicle exhausts (fuels burned under high temp.)

Question 35

source of CO

Answer 35

incomplete combustion of fuel in vehicle engines

Question 36

effect of CO2

Answer 36

greenhouse gas → GLOBAL WARMING

acidic gas → OCEAN ACIDIFICATION

Question 37

effect of SO2

Answer 37

respiratory diseases

acidic gas → dissolves in atmosphere and falls as ACID RAIN

Question 38

effect of NO, NO2

Answer 38

respiratory diseases

acidic gas → dissolves in atmosphere and falls as ACID RAIN

Question 39

effect of CO

Answer 39

combines with haemoglobin → damages RED BLOOD CELL’S ABILITY TO CARRY OXYGEN

Question 40

how to control CO2 pollution?

Answer 40

reduce use of fossil fuels (eg. generate electricity using renewable fuels)

Question 41

how to control SO2 pollution?

Answer 41

pass through Ca(OH)2 → neutralized

Question 42

how to control NO, NO2 pollution?

Answer 42

CATALYTIC CONVERTER in vehicles to convert NO, NO2 into N2

Question 43

how to control CO pollution?

Answer 43

CATALYTIC CONVERTER in vehicles convert CO into CO2

Question 44

what are the 3 stages of WATER PURIFICATION?

Answer 44

1. Sedimentation
   large insoluble particles are removed as they settle to bottom of tank
2. Filtration
   smaller insoluble particles are removed as water trickles through layers of sand and gravel
3. Chlorination
   chlorine gas sterilizeswater (kills microorganisms)