C3.4 Analysis and Synthesis

Question 1

State the colour for the flame test of a Lithium Ion (Li⁺)

Answer 1

Crimson/red

Question 2

State the colour for the flame test of a Sodium Ion (Na⁺)

Answer 2

Orange

Question 3

State the colour for the flame test of a Potassium Ion (K⁺)

Answer 3

Lilac/Purple

Question 4

State the colour for the flame test of a calcium ion (Ca²⁺)

Answer 4

red

Question 5

State the colour for the flame test of a Barium Ion (Ba²⁺)

Answer 5

Green

Question 6

State the observation when a few drops of sodium hydroxide is added to iron (II) chloride

Answer 6

green precipitate/solid

Question 7

State the observation when a few drops of sodium hydroxide is added to iron (III) chloride

Answer 7

brown precipitate/solid

Question 8

State the observation when a few drops of sodium hydroxide is added to copper chloride

Answer 8

blue precipitate/solid

Question 9

State the observation when a few drops of sodiurecipitate/solidm hydroxide is added to calcium chloride

Answer 9

white precipitate/solid

Question 10

State the observation when a few drops of sodium hydroxide is added to magnesium chloride

Answer 10

white precipitate/solid

Question 11

State the observation when a few drops of sodium hydroxide is added to aluminium chloride

Answer 11

white precipitate/solid

Question 12

State the observation when an excess of sodium hydroxide is added to aluminium chloride

Answer 12

precipitate dissolves/disappears

Question 13

Describe how to distinguish between calcium and magnesium ions

Answer 13

flame test

calcium ions give a red flame

Question 14

Describe the test for carbonate ions

Answer 14

Add an acid
Bubbles
of carbon dioxide
which turns limewater cloudy

Question 15

Describe the test for sulphate ions

Answer 15

Add barium chloride

makes a white precipitate (solid)

Question 16

Describe the test for chloride ions

Answer 16

Add silver nitrate

makes a white precipitate (solid)

Question 17

Describe the test for bromide ions

Answer 17

Add silver nitrate

makes a cream precipitate (solid)

Question 18

Describe the test for iodide ions

Answer 18

Add silver nitrate

makes a yellow precipitate

Question 19

Give two advantages of using instrumental methods of analysis. [1]

Answer 19

fast
sensitive
accurate

Question 20

Describe how to use apparatus to do a titration using 25 cm³ of dilute hydrochloric acid.
In your answer you should include:
• how you will determine the end point of the titration
• how you will make sure the result obtained is accurate. [4]

Answer 20

• put sodium hydroxide (alkali) in the burette
• add drop wise until the indicator turns pink
• whilst swirling
• read at the meniscus
• read the start and end volumes

Question 21

What is meant by a closed system?

Answer 21

nothing can enter and nothing can leave the reaction

Question 22

Explain why, when a reversible reaction reaches equilibrium, the reaction appears to have stopped. [2]

Answer 22

forward and backward reactions have same rate [1]

so there is no (overall) change in concentration of reactants and products [1]

Question 23

Name a natural resource from which hydrogen is produced for the Haber process

Answer 23

methane (natural gas)

Question 24

What happens to the amount of ammonia produced at equilibrium if the pressure is increased?
Give a reason for your answer. [2]

Answer 24

the amount (of ammonia) increases [1]
the equilibrium moves to the side (of the equation) with fewer (gaseous) molecules / moles [1]

Question 25

Why is a temperature much lower than 450 °C not used for the Haber process? [1]

Answer 25

rate of reaction (too) slow [1]

Question 26

Explain how ammonia is separated from unreacted nitrogen and hydrogen in the Haber process [2]

Answer 26

(gases) cooled [1]

ammonia condensed [1]

Question 27

State and explain how a decrease in temperature would affect the yield of ammonia at equilibrium [2]

Answer 27

increase yield [1]

because (forward) reaction is exothermic [1]

Question 28

Name a natural resource from which nitrogen is obtained for the Haber process

Answer 28

air

Question 29

Name the catalyst used in the Haber process

Answer 29

Iron

Question 30

Explain why high pressures need to be compromised in the Haber process

Answer 30

too expensive to maintain/requires large amounts of energy