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Required practicals > Chemistry > Flashcards

Chemistry Flashcards

1
Q

RP 1:

Aim:

A

RP 1:

To prepare a pure, dry sample of a soluble salt from an insoluble oxide or
carbonate.

(using a Bunsen burner to heat dilute acid and a water bath or electric heater to evaporate the solution)

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2
Q

RP 1:

What equipment does this practical require?

A

RP 1:

● 1.0 M dilute sulfuric acid
● Copper (II) oxide powder
● A spatula
● A glass rod
● A measuring cylinder
● Two beakers: one 100 cm^3 and one 250 cm^3
● Bunsen burner
● Tripod
● Gauze
● Heatproof mat
● Filter funnel and paper
● A small conical flask
● An evaporating basin
● A crystallising dish
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3
Q

RP 1:

What’s the First step of making salts?

A

RP 1:

  1. Measure 20 cm^3 sulfuric acid into a measuring cylinder and pour it into beaker
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4
Q

RP 1:

What’s the Second step of making salts?

A

RP 1:

  1. Heat the acid gently using a Bunsen burner
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5
Q

RP 1:

What’s the Third step of making salts?

A

RP 1:

  1. Add small amounts of insoluble base in this case copper oxide in excess (until no more reacts thus no more effervescence is produced)
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6
Q

RP 1:

What’s the Fourth step of making salts?

A

RP 1:

  1. Filter using filter paper and funnel the solution to remove the excess copper oxide
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7
Q

RP 1:

What’s the Fifth step of making salts?

A

RP 1:

  1. Pour the solution into the evaporating basin
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8
Q

RP 1:

What’s the Sixth step of making salts?

A

RP 1:

  1. Evaporate the solution using a water bath until crystals start to form
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9
Q

RP 1:

What’s the Seventh step of making salts?

A

RP 1:

  1. Leave the evaporating basin in a cool place for at least 24 hours
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10
Q

RP 1:

What’s the Eighth step of making salts?

A

RP 1:

  1. Gently pat the crystals dry between two pieces of filter paper
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11
Q

RP 1:

Safety Precautions:

A

RP 1:

● Wear safety goggles as sulphuric acid is corrosive.
● Make sure hair is tied back.
● When the Bunsen burner is not in use, turn it off or leave it on the orange safety flame

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12
Q

RP 1:

How could you prepare a sample of pure, dry copper sulfate crystals from a sample of insoluble copper oxide?

A

RP 1:

  • React sulfuric acid with excess copper oxide
  • Filter to remove the excess copper oxide
  • Heat the solution to start evaporation
  • Turn off the heat and leave until all of the water has evaporated
  • Left with copper sulfate crystals
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13
Q

RP 1:

What are two methods of separating mixtures?

A

RP 1:

Filtration, Crystallisation

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14
Q

RP 1:

Magnesium and dilute hydrochloric acid react to produce magnesium chloride
solution and hydrogen.
Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)
(i) State two observations that could be made during the reaction.

A

RP 1:

effervescence / bubbling / fizzing / bubbles of gas

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15
Q

RP 1:

Outline a suitable method for obtaining a sample of pure, dry salt crystals:

A

RP 1:

  1. Measure 20 cm3 sulfuric acid into a measuring cylinder and pour it into beaker
  2. Heat the acid gently using a Bunsen burner
  3. Add small amounts of insoluble base in this case copper oxide in excess (until no more reacts thus no more effervescence is produced)
  4. Filter using filter paper and funnel the solution to remove the excess copper oxide
  5. Pour the solution into the evaporating basin
  6. Evaporate the solution using a water bath until crystals start to form
  7. Leave the evaporating basin in a cool place for at least 24 hours
  8. Gently pat the crystals dry between two pieces of filter paper
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16
Q

RP 2:

What is neutralisation?

  • what does is result in
A

RP 2:

The reaction between an acid and a base

  • Forms a neutral solution of a salt and water (Acid + Alkali → Salt + Water)
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17
Q

RP 2:

Aim:

A

RP 2:

To find the concentration of a dilute sulfuric acid solution, using a sodium hydroxide solution of known concentration

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18
Q

RP 2:

What equipment does this practical require?

A

RP 2:

● 25 cm^3 volumetric pipette
● Pipette filler
● 50 cm^3 burette
● 250 cm^3 conical flask
● Small funnel
● Clamp stand and clamp
● White tile
● 0.1 M sodium hydroxide solution
● Sulfuric acid
● Phenolphthalein indicator
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19
Q

RP 2:

What’s the First Step of performing a titration?

A

RP 2:

  1. Use the pipette to measure 25cm^3 of sodium hydroxide into the conical flask
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20
Q

RP 2:

What’s the Second Step of performing a titration?

A

RP 2:

  1. Place the conical flask on a white tile.
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21
Q

RP 2:

What’s the Third Step of performing a titration?

A

RP 2:

  1. Fill the burette with sulphuric acid using a funnel
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22
Q

RP 2:

What’s the Fourth Step of performing a titration?

A

RP 2:

  1. Record the initial reading of acid in the burette
    - Make sure to always take readings from the bottom of the meniscus
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23
Q

RP 2:

What’s the Fifth Step of performing a titration?

A

RP 2:

  1. Add a 5 drops of indicator in this case phenolphthalein to the conical flask
24
Q

RP 2:

What’s the Sixth Step of performing a titration?

A

RP 2:

  1. Slowly open the burette tap while swirling the conical flask
25
Q

RP 2:

What’s the Seventh Step of performing a titration?

A

RP 2:

  1. Add acid drop-by-drop near the endpoint
    - At this point the colour will start to change slightly
26
Q

RP 2:

What’s the Eighth Step of performing a titration?

A

RP 2:

  1. Close the burette when a colour change occurs in phenolphthalein
    - The solution turns from pink to colourless
27
Q

RP 2:

What’s the Ninth Step of performing a titration?

A

RP 2:

  1. Record the final reading of acid in the burette and calculate the titre
    - This is the volume of acid used to neutralise the alkali
28
Q

RP 2:

What’s the Tenth Step of performing a titration?

A

RP 2:

10. Repeat until you have concordant results
These are within 0.1cm3 of each other

29
Q

RP 2:

What’s the Eleventh Step of performing a titration?

A

RP 2:

  1. Present results in a table and calculate the mean titre discarding any anomalies when calculating the mean
30
Q

RP 2:

What’s the Twelfth Step of performing a titration?

A

RP 2:

  1. Calculate the number of moles of sodium hydroxide used in the titration by looking at the balanced symbol equation for the reaction
31
Q

RP 2:

What’s the Thirteenth Step of performing a titration?

A

RP 2:

  1. Work out the concentration of sulphuric acid using the formula (concentration= moles/volume)
32
Q

RP 2:

Safety Precautions:

A

RP 2:

● Wear safety goggles when working with acids
● Tie hair back
● Report any broken glassware immediately

33
Q

RP 2:

Outline a suitable method that could be used to perform a titration:

A

RP 2:

  1. Use the pipette to measure 25cm3
    of sodium hydroxide into the conical flask.
  2. Place the conical flask on a white tile.
  3. Fill the burette with sulphuric acid using a funnel.
  4. Record the initial reading of acid in the burette.
    - Make sure to always take readings from the bottom of the meniscus.
  5. Add a 5 drops of indicator in this case phenolphthalein to the conical flask.
  6. Slowly open the burette tap while swirling the conical flask.
  7. Add acid drop-by-drop near the endpoint.
    - At this point the colour will start to change slightly.
  8. Close the burette when a colour change occurs in phenolphthalein.
    - The solution turns from pink to colourless.
  9. Record the final reading of acid in the burette and calculate the titre
  10. Repeat until you have concordant results
    (These are within 0.1cm3 of each other)
  11. Present results in a table and calculate the mean titre discarding any anomalies when calculating the mean
  12. Calculate the number of moles of sodium hydroxide used in the titration by looking at the balanced symbol equation for the reaction
  13. Work out the concentration of sulphuric acid using the formula (concentration= moles/volume)
34
Q

RP 2:

Why is a single indicator used rather than universal indicator?

A

RP 2:

Because the end point needs to be observed by a sudden colour change

35
Q

RP 2:

Why should a white tile be used in a titration reaction?

A

RP 2:

It makes the colour change in the reacting mixture easier to see.

36
Q

RP 2:

What colour is phenolphthalein in acid and alkali?

A

RP 2:

Acid - Colourless

Alkali - Pink

37
Q

RP 2:

What colour is Litmus in acid and alkali?

A

RP 2:

Acid - Red

Alkali - Blue

38
Q

RP 2:

What colour is Methyl Orange in acid and alkali?

A

RP 2:

Acid - Red

Alkali - Yellow

39
Q

RP 2:

Neutralisation reactions are exothermic.
Suggest what this means in terms of energy transfer:

A

RP 2 :

An exothermic reaction involves energy being transferred from the reacting chemicals to the surroundings. They can be shown by a rise in temperature

40
Q

RP 2:

Sulfuric acid is a strong acid.

What is meant by a strong acid?

A

RP 2:

Sulfuric acid is completely ionised in aqueous solution // when dissolved in water

41
Q

RP 4:

Aim:

A

RP 4:

To investigate the variables that affect temperature change during chemical reactions

42
Q

RP 4:

What equipment does this practical require?

A

RP 4:

● 2 M hydrochloric acid
● 2 M sodium hydroxide solution
● Expanded polystyrene cups and lids with thermometer holes
● Thermometers

43
Q

RP 4:

Outline a suitable method for testing the effect of acid concentration on the energy released during a neutralisation reaction between hydrochloric acid and sodium hydroxide:

A

RP 4:

1) Put 25 cm^3 of 0.25 mol/dm^3 HCl and NaOH in separate beakers
2) Place both beakers in a water bath set to 25ºC, until they both reach 25ºC
3) Add the HCl followed by the NaOH to a polystyrene cup with a lid
4) Take the temperature of the mixture every 30 seconds, and record the highest temperature
5) Repeat steps 1-4 using 0.5 mol/dm^3 and then 1 mol/dm^3 of hydrochloric acid

44
Q

RP 4:

What is the First Step in an experiment investigating variables affecting temperature changes?

A

RP 4:

1)Put 25 cm^3 of 0.25 mol/dm^3 HCl and NaOH in separate beakers

45
Q

RP 4:

What is the Second Step in an experiment investigating variables affecting temperature changes?

A

RP 4:

2)Place both beakers in a water bath set to 25ºC, until they both reach 25ºC

46
Q

RP 4:

What is the Third Step in an experiment investigating variables affecting temperature changes?

A

RP 4:

3)Add the HCl followed by the NaOH to a polystyrene cup with a lid

47
Q

RP 4:

What is the Fourth Step in an experiment investigating variables affecting temperature changes?

A

RP 4:

4)Take the temperature of the mixture every 30 seconds, and record the highest temperature

48
Q

RP 4:

What is the Fifth Step in an experiment investigating variables affecting temperature changes?

A

RP 4:

5)Repeat steps 1-4 using 0.5 mol/dm^3 and then 1 mol/dm^3 of hydrochloric acid

49
Q

RP 4:

Safety Precautions:

A

RP 4:

● Wear safety goggles

50
Q

RP 4:

How could the amount of energy lost to the surroundings be reduced?

A

RP 4:

  • Mix the reactants in a polystyrene cup
  • Place the polystyrene cup in a beaker of cotton wool
  • Keep a lid on the cup to reduce energy loss through evaporation
51
Q

RP 4:

Why should both chemicals start at the same temperature?

A

RP 4:

To ensure that their individual temperatures do not have an effect on the temperature recorded once combined

52
Q

RP 4:

Why is it important to stir the mixture when taking a temperature reading?

A

RP 4:

  • To ensure that the temperature is consistent throughout the mixture
  • To ensure that the reactants have fully reacted
53
Q

RP 4:

How could the temperature be measured more precisely?

A

RP 4:

By using a digital thermometer

54
Q

RP 4:

How could the temperature be measured more reliably?

A

RP 4:

By repeating the experiment and calculating a mean temperature measurement

55
Q

RP 4:

What variables must be controlled during this experiment?

A

RP 4:

  • Alkali concentration
  • Alkali volume
  • Acid volume
  • Initial temperatures of each reactant
  • External temperatures

Required practicals (3 decks)

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