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chemistry (paper one) > acids and bases (topic 4) > Flashcards

acids and bases (topic 4) Flashcards

1
Q
A
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2
Q
A

there is a large amount of acid and a small amount of water

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3
Q
A

the alkali is completely ionised in solution in water

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4
Q

what conclusions can you make about the relative accuracy of each pH meter, explain each conclusion

A
  • pH meter 1 is the most accurate because the readings are closest to the actual pH
  • pH meter 2 is not accurate because all of the readings are too high
  • pH meter 3 is the least accurate because readings were the furthest from the actual pH
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5
Q

what is the trend in the relationship between concentration of hydrogen ions and pH (1)

A

the higher the concentration of hydrogen ions, the lower the pH

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6
Q
A

pipette

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7
Q
A

H+

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8
Q

describe how the student would use the equipment in the image to complete the titration (4)

A
  • add potassium hydroxide solution to the conical flask
  • add a few drops of indicator
  • add the sulfuric acid from the burette
  • until the colour of the indicator changes
  • read the volume from the burette
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9
Q

(6)

A
  • measure the volume of acid A
  • add indicator to the acid
  • add sodium hydroxide solution
  • until the colour changes
  • record volume of sodium hydroxide - solution added
  • repeat procedure with acid B
  • compare the two volumes of sodium hydroxide solution to find which sample is more concentrated
    _____
  • pipette to measure volume of acid
  • use a few drops of indicator
  • swirl
  • use a white tile
  • read volume from bottom of meniscus
  • repeat and take a mean
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10
Q

which acid should the student use to produce lead nitrate

A

nitric acid

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11
Q

which of the the following is a base the student could use to produce lead nitrate

A

lead oxide

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12
Q

(4)

A
  • add excess sodium sulfate solution rather than a few drops
  • so more reaction occurs to form more lead sulfate
  • filter the reaction mixture rather than pour off the liquid
  • so none of the lead sulfate is lost on separation
  • wash the lead sulfate
  • so the impurities are removed
  • place the lead sulfate in an oven
  • so the lead sulfate is dry
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13
Q
A
  • nitric acid
  • water
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14
Q
A
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15
Q
A

the carbonate would fizz

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16
Q

describe how crystals of calcium chloride can be made from calcium carbonate and dilute hydrochloric acid (4)

A
  • add excess calcium carbonate to acid and stir
  • remove excess calcium carbonate by filtering
  • warm until a saturated solution forms
  • leave to cool
17
Q
A
  • white precipitate forms
  • insoluble in excess
18
Q

would the result predicted in part a) prove that the salt contains calcium ions, explain your answer

A
  • no
  • the same result would be obtained with magnesium ions
19
Q

describe an additional test the student could do that would prove the salt contains calcium ions (other than crystals dissolved in salt water)

A
  • flame test
  • calcium gives a red flame
20
Q

give one other type of substance that can react with an acid to form a soluble salt (other than metal oxides

A
  • metal
  • metal hydroxide
  • metal carbonate
  • alkali
21
Q

describe a method to make pure, dry crystals of copper sulfate, from a metal oxide and a dilute acid (6)

A
  • use copper oxide and sulfuric acid
  • add sulfuric acid to a beaker
  • warm the sulfuric acid in a water bath
  • add copper oxide and stir
  • continue adding until copper oxide is in excess
  • filter the mixture using a funnel and filter paper
  • to remove excess copper oxide
  • heat solution in an evaporating basin to crystallisation point
  • leave to crystallise
  • pat dry with filter paper
22
Q

the student used copper oxide as the base in the reaction to produce copper sulfate, name and give the chemical formula of the acid used

A
  • sulfuric acid
  • H2SO4
23
Q

explain the purpose of following steps in the students method:
add copper oxide until it is in excess

A
  • all acid reacts
  • acid is neutralised
    _
    (copper oxide is a base because it will react with acids and neutralise them, but it is not an alkali because it does not dissolve in water)
24
Q

ethanol is flammable, suggest how the scientist could evaporate off the ethanol safely (1)

A
  • heat with a water bath
  • heat with an electric heater
25
Q

explain why the scientist adds excess zinc rather than excess iodine (3)

A
  • to make sure that all the iodine reacts
  • as excess iodine would remain in solution
  • so iodine could not be filtered off or so the zinc iodide would not be pure
26
Q
A
27
Q

define a neutralisation reaction

A

the reaction of an acid with an alkali (to form a salt plus water)

28
Q
A
29
Q
A
  • indicator
  • the student will observe a change in colour
30
Q

describe one way in which the student can make her burette reading as accurate as possible

A
  • take readings at eye level
  • take readings from bottom of meniscus
  • make sure there is no air in the burette
  • add the NaOH drop by drop
31
Q
A

Na3PO4

32
Q

the student writes an ionic equation for the reaction (dilute sodium hydroxide reacts with dilute hydrochloric acid) use the ionic equation and values from the graph to explain how the pH changes during the reaction
_
H+ + OH– ➔ H2O

A
  • H+ ions from the acid give low pH
  • OH- ions from alkali give high pH
  • 25 cm3 is neutralisation
33
Q

the student started with 20.0 cm^3 of dilute hydrochloric acid in the beaker, explain how his results show that the acid is more concentrated than the dilute sodium hydroxide (1)

A

experiment uses 25.0 cm3 sodium hydroxide for neutralisation (20cm^3 is not neutral or 20cm^3 is still acidic)

34
Q

what mass of sodium hydroxide would be needed to make 46.8 g of sodium chloride

A
35
Q

give the symbol equation for the reaction

A

chemistry (paper one) (24 decks)

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