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GCSE Chemistry > C3 - Analysis & Synthesis > Flashcards

C3 - Analysis & Synthesis Flashcards

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1
Q

What are the two main methods for testing for positive ions?

A
  • Flame test

- Reaction with sodium hydroxide.

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2
Q

How is a flame test carried out?

A
  • The compound is put on a cleaned wire loop
  • The loop is then held in a Bunsen burner.
  • The colour of the flame can be used to identify a positive ion.
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3
Q

What colour flame does lithium produce?

A

Crimson

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4
Q

What colour flame does sodium produce?

A

Yellow

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5
Q

What colour flame does potassium produce?

A

Lilac

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6
Q

What colour flame does calcium produce?

A

Red

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7
Q

What colour flame does barium produce?

A

Green

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8
Q

What possible elements are present if a white precipitate forms in sodium hydroxide?

A

Al3+, Ca2+, Mg2+

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9
Q

How is it possible to distinguish between Al, Ca and Mg ions?

A
  • Adding more NaOH causes aluminium ions to dissolve.

- Calcium can be identified with a flame test.

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10
Q

Which ions produce a blue precipitate with NaOH?

A

Copper(II)

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11
Q

Which ions produce a green precipitate with NaOH?

A

Iron(II)

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12
Q

Which ions produce a brown precipitate with NaOH?

A

Iron(III)

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13
Q

How can negative carbonate ions be identified?

A
  • Adding dilute acid produces CO2 gas.

- Limewater is then turned cloudy.

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14
Q

How can negative halide ions be identified?

A
  • Nitric acid then silver nitrate solution is added.

- If a precipitate forms, halides are present.

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15
Q

Which ions produce a white precipitate with silver nitrate?

A

Chloride

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16
Q

Which ions produce a cream precipitate with silver nitrate?

A

Bromide

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17
Q

Which ions produce a yellow precipitate with silver nitrate?

A

Iodide

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18
Q

How can negative sulfate ions be identified?

A
  • Hydrochloric acid then barium chloride is added.

- If a white precipitate forms, sulfate ions are present.

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19
Q

What is titration used for?

A

To measure how much acid and alkali react completely.

20
Q

What is the end-point of a reaction?

A

The point at which the acid and alkali have reacted completely.

21
Q

What is a pipette used for?

A

Measure out a fixed solution.

22
Q

What is a burette used for?

A

Measuring the volume added.

23
Q

How is the concentration of a solution calculated?

A
  • Calculate the mass in 1cm3 of solution.
  • Calculate mass of solute in 1000cm3 of solution.
  • Convert the mass to moles.
24
Q

How is the mass of solute calculated?

A
  • Calculate the mass of the solute in 1dm3.
  • Calculate mass in 1cm3.
  • Calculate the mass in the given volume.
25
Q

What technique is used to analyse DNA?

A

Gel electrophoresis

26
Q

Give two examples of chemical analysis in medicine.

A
  • DNA can be matched to find suitable donors.

- Metal concentrations can be analysed to indicate joint failures.

27
Q

What is the point of equilibrium?

A

When the rate of forward and reverse reactions are equal.

28
Q

What happens when a system of equilibrium is changed?

A

When a system of equilibrium is subjected to a change then the position of equilibrium will shift to oppose the change.

29
Q

How does changing the pressure affect reversible reactions involving gases?

A
  • Increasing the pressure favours the reaction with the least number of molecules of gas formed.
  • Decreasing the pressure favours the reaction with the greater number of molecules of gas formed.
30
Q

How does changing the temperature affect reversible reactions?

A
  • Increasing the temperature favours the endothermic reaction.
  • Decreasing the temperature favours the exothermic reaction.
31
Q

If the forward reaction of a reversible reaction is exothermic, what must the reverse reaction be?

A

Endothermic

32
Q

Give five examples for the uses of ammonia.

A
  • Dye
  • Fibre making
  • Nitric acid
  • Fertiliser
  • Explosives
33
Q

What makes the Haber process so efficient?

A
  • Unreacted hydrogen and oxygen are reused.

- Steam is used to turn generators.

34
Q

How is the nitrogen for the Haber process obtained?

A

Hydrogen is burned with air to give nitrogen and water.

35
Q

How is the ammonia gas collected?

A

It is condensed into a tank.

36
Q

How can the yield of ammonia be changed?

A

Increasing the pressure.

37
Q

Why does an increase in pressure increase the yield of ammonia?

A

There are four molecules going in and two going out meaning the pressure favours the forward reaction.

38
Q

What pressure is the Haber process undertaken at?

A

200atm

39
Q

Why is the Haber process done at the given pressure?

A

It gives a high yield at a lesser expense.

40
Q

What temperature is the Haber process carried out at?

A

200C

41
Q

Why can’t the Haber process be carried out at a lower temperature?

A

The rate of reaction would be too slow.

42
Q

Why can’t the Haber process be carried out at a higher temperature?

A
  • The forward reaction is exothermic.

- A lower temperature favours the forward reaction.

43
Q

What is used as a catalyst in the Haber process?

A

Iron

44
Q

What does the presence of a catalyst do in the Haber process?

A
  • Doesn’t increase yield.

- Forms ammonia faster.

45
Q

Since you’ve been using these flashcards for free, please consider making a small donation for the hundreds of hours it took to make them.

A

http://bit.ly/21T6H3W

Thank you and good luck!

GCSE Chemistry (19 decks)

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