5 - Acids Flashcards

1
Q

Define acid

A

pH lower than 7

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2
Q

Define alkali/base

A
  • pH higher than 7

- alkalis are bases that can dissolve

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3
Q

Define indicator

A

A substance that tells you whether something is an acid or alkali. Some indicators can give an idea of pH

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4
Q

Define neutralisation

A

Acid + alkali = salt + water, mixing an acid and an alkali to form a neutral solution

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5
Q

Define salt

A
  • neutral ionic compound

- eg. potassium chloride, sodium chloride, lithium fluoride

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6
Q

Define soluble

A
  • can dissolve
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7
Q

Define insoluble:

A
  • cannot dissolve
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8
Q

Colour of acid in Universal Indicator:

A
  • red
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9
Q

Colour of acid in Litmus paper:

A
  • red
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10
Q

Colour of acid in Methyl orange:

A
  • red
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11
Q

Colour of acid in phenolphtalein:

A
  • colourless
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12
Q

Colour of alkali in Universal Indicator

A
  • purple/blue
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13
Q

Colour of alkali in Litmus paper:

A
  • blue
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14
Q

Colour of alkali in Methyl orange:

A
  • yellow
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15
Q

Colour of alkali in Phenolphthalein:

A
  • pink
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16
Q

Colour of neutral solution in Universal Indicator:

A
  • green
17
Q

Colour of neutral solution in Litmus paper:

A
  • no change
18
Q

Colour of neutral solution in Methyl orange:

A
  • orange
19
Q

Colour of neutral solution in Phenolphthalein:

A
  • colourless
20
Q

What is an acid in an aqueous solution a source of?

A
  • a source of hydrogen ions

- hydrogen ions are positively charged

21
Q

What is an alkali in an aqueous solution a source of?

A
  • hydroxide ions

- hydroxide ions are negatively charged

22
Q

How to calculate moles?

A

mass/relative molecular mass

23
Q

“Calculate the mass of KOH when HNO3+ KOH = KNO3+ H2O when HNO3is 3g”

A

HNO3: mass = 3g, Mr = 63, moles = 0.048KOH : Mr = 56, moles = 0.048, mass = mol by Mr = 0.048 by 56 = 2.67g

24
Q

What is neutralisation?

A

acid + base = salt + water

25
Q

How to calculate the concentration of an acid or alkali?

A

Titration

26
Q

What is the apparatus needed for titration?

A
  • burette
  • conical flask
  • pipette
  • pipette filler
  • clamp and stand
27
Q

What is the titre (cm3) in titration?

A

The difference between the reading at the start and the final reading gives the volume of the acid (or alkali) added.

28
Q

When do we know when neutralisation has taken place in a titration experiment?

A
  • when the alkali in the conical flask which phenolphthalein has been added turns colourless
29
Q

metal + acid = ?

A

metal + acid = salt + hydrogen

30
Q

acid + base = ?

A

acid + base = salt + water

31
Q

acid + carbonate = ?

A

acid + carbonate = salt + water + carbon dioxide

32
Q

Are common sodium, potassium and ammonium compouds soluble or insoluble?

A

soluble

33
Q

Are all nitrates soluble or insoluble?

A

soluble

34
Q

Are common chlorides soluble or insoluble? Which 2 are an exception?

A
  • soluble

- silver and lead(II) are insoluble

35
Q

Are common sulfates soluble or insoluble? Which 3 are an exception?

A
  • soluble

- barium, calcium and lead(II) are insoluble

36
Q

Are common carbonates soluble or insoluble? Which 3 are an exception?

A
  • insoluble

- sodium, potassium and ammonium are soluble

37
Q

Are common hydroxides soluble or insoluble? Which 3 are exceptions?

A
  • insoluble

- sodium, potassium and calcium are soluble

38
Q

Method of knowing if a salt is soluble:

A
  • measure out acid
    If base is soluble:
  • add base (excess)
    If base is insoluble:
  • add base
  • when fizzing stops and the solid has disappeared, add more base (keep repeating). There should now be excess, unreacted powder in the flask
  • filter the mixture
    For both methods, then:
  • pour the solution into an evaporating dish and heat to concentrate the solution by evaporating some of the water
  • leave the solution to cool and crystallize
  • filter off the crystals and pat dry between clean dry filter papers
39
Q

Method of knowing if a salt is insoluble:

A
  • measure out acid
  • add base (excess) until no more precipitate is produced
  • filter the mixture
  • pat dry between clean dry filter papers