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IGCSE Chemistry > C4+C10 Acids and Bases > Flashcards

C4+C10 Acids and Bases Flashcards

1
Q

what are ACIDS?

what color do acids turn litmus paper to?

A

compounds that break into H+ ions

turn litmus paper RED

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2
Q

what are BASES?

what color do bases turn litmus paper to?

A

compounds that break into OH- ions

turn litmus paper BLUE

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3
Q

what are ALKALIS?

A

soluble bases

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4
Q

what is the pH scale?

A

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

  • lots of H+ means low pH
  • lots of OH- means high pH
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5
Q

acid + metal = ?

A

salt + hydrogen

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6
Q

acid + metal oxide = ?

A

salt + water

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7
Q

acid + metal hydroxide = ?

A

salt + water

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8
Q

acid + metal carbonate = ?

A

salt + water + carbon dioxide

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9
Q

acid + alkali = ?

A

salt + water

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10
Q

how are salts formed?

A

when a base neutralizes an acid

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11
Q

what are the three methods of SALT PREPARATION?

what are the REACTANTS and PRODUCTS of each?

A

EXCESS:
insoluble base + acid = soluble salt + water

TITRATION:
soluble base + acid = soluble salt + water

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

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12
Q

what are the steps of the EXCESS method?

draw a diagram and explain step by step (6)

A
  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
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13
Q

EXCESS METHOD:

  1. why is acid warmed?
  2. why is an excess of insoluble base used?
  3. why do you filter the mixture?
A
  1. to speed up reaction
  2. so all acid react
  3. remove excess insoluble base
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14
Q

what are the steps of the TITRATION method?

draw a diagram and explain step by step (6)

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

—– repeat without indicator —–

  1. HEAT (evaporating dish over bunsen burner) to evaporate water → CRYSTALS form
  2. leave to cool
  3. FILTER to get crystal and DRY the crystals
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15
Q

TITRATION METHOD:

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

A

to know the volume of acid needed to neutralize the solution

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16
Q

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

A
  • MIX the two soluble salts
  • FILTER to get precipitate
  • WASH the precipitate with distilled water
  • leave to DRY
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17
Q

define concentration of the solution

A

the number of moles per dm3

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18
Q

how to convert dm3 to cm3?

A

1 dm3 = 1000 cm3

19
Q

how to convert moles into grams?

A

(mol/dm3) x (molar mass)

20
Q

what are some SAFETY PRECAUTIONS during salt preparation?

A

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

21
Q

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

A

check notes :)

22
Q

what salts are ALWAYS SOLUBLE?

A

SPA - sodium, potassium, ammonium

Nitrates

23
Q

what salts are SOLUBLE most of the time?

what are the exceptions?

A

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

Group 7 
(except with Pb, Hg, Ag)
24
Q

what salts are INSOLUBLE most of the time?

what are the exceptions?

A

CO3
OH
(except when with SPA)

25
Q

how to calculate the CONCENTRATION OF SOLUTION?

A

Concentration = #Moles / Volume

26
Q

how to calculate #MOLES?

A

Moles = Mass / Molar Mass

27
Q

LIMESTONE → LIME

  • how? what’s this method called?
  • diagram?
  • word equation?
  • observations?
A
  • HEAT limestone for 10 mins
  • THERMAL DECOMPOSITION
  • CaCO3 → CaO (lime) + CO2
  • CaCO3 chip turns black then white
28
Q

LIME → LIMEWATER / SLAKE SLIME

  • how?
  • word equation?
  • observations?
A
  • add WATER to heated limestone
  • CaO + H2O → Ca(OH)2
  • EXOTHERMIC rxn, WATER HISSES
29
Q

similarity and difference between limewater and slake lime?

A

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

30
Q

LIMEWATER → CaCO3

  • how?
  • word equation?
  • observations?
A
  • BLOW BUBBLES through solution
  • Ca(OH)2 + CO2 → CaCO3 + H2O
  • limewater becomes CLOUDY (insoluble CaCO3 forms)
31
Q

uses of LIMESTONE

A

NEUTRALIZE acidic soil and industrial waste

32
Q

source of CO2

A

burning fossil fuels, respiration

33
Q

source of SO2

A

burning fossil fuels

34
Q

source of nitrogen oxides (NO, NO2 N2O)

A

vehicle exhausts (fuels burned under high temp.)

35
Q

source of CO

A

incomplete combustion of fuel in vehicle engines

36
Q

effect of CO2

A

greenhouse gas → GLOBAL WARMING

acidic gas → OCEAN ACIDIFICATION

37
Q

effect of SO2

A

respiratory diseases

acidic gas → dissolves in atmosphere and falls as ACID RAIN

38
Q

effect of NO, NO2

A

respiratory diseases

acidic gas → dissolves in atmosphere and falls as ACID RAIN

39
Q

effect of CO

A

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

40
Q

how to control CO2 pollution?

A

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

41
Q

how to control SO2 pollution?

A

pass through Ca(OH)2 → neutralized

42
Q

how to control NO, NO2 pollution?

A

CATALYTIC CONVERTER in vehicles to convert NO, NO2 into N2

43
Q

how to control CO pollution?

A

CATALYTIC CONVERTER in vehicles convert CO into CO2

44
Q

what are the 3 stages of WATER PURIFICATION?

A
  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)

IGCSE Chemistry (9 decks)

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