C3.4 Analysis and Synthesis Flashcards
State the colour for the flame test of a Lithium Ion (Li+)
Crimson/red
State the colour for the flame test of a Sodium Ion (Na+)
Orange
State the colour for the flame test of a Potassium Ion (K+)
Lilac/Purple
State the colour for the flame test of a calcium ion (Ca2+)
red
State the colour for the flame test of a Barium Ion (Ba2+)
Green
State the observation when a few drops of sodium hydroxide is added to iron (II) chloride
green precipitate/solid
State the observation when a few drops of sodium hydroxide is added to iron (III) chloride
brown precipitate/solid
State the observation when a few drops of sodium hydroxide is added to copper chloride
blue precipitate/solid
State the observation when a few drops of sodiurecipitate/solidm hydroxide is added to calcium chloride
white precipitate/solid
State the observation when a few drops of sodium hydroxide is added to magnesium chloride
white precipitate/solid
State the observation when a few drops of sodium hydroxide is added to aluminium chloride
white precipitate/solid
State the observation when an excess of sodium hydroxide is added to aluminium chloride
precipitate dissolves/disappears
Describe how to distinguish between calcium and magnesium ions
flame test
calcium ions give a red flame
Describe the test for carbonate ions
Add an acid
Bubbles
of carbon dioxide
which turns limewater cloudy
Describe the test for sulphate ions
Add barium chloride
makes a white precipitate (solid)
Describe the test for chloride ions
Add silver nitrate
makes a white precipitate (solid)
Describe the test for bromide ions
Add silver nitrate
makes a cream precipitate (solid)
Describe the test for iodide ions
Add silver nitrate
makes a yellow precipitate
Give two advantages of using instrumental methods of analysis. [1]
fast
sensitive
accurate
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]
- 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
What is meant by a closed system?
nothing can enter and nothing can leave the reaction
Explain why, when a reversible reaction reaches equilibrium, the reaction appears to have stopped. [2]
forward and backward reactions have same rate [1]
so there is no (overall) change in concentration of reactants and products [1]
Name a natural resource from which hydrogen is produced for the Haber process
methane (natural gas)
What happens to the amount of ammonia produced at equilibrium if the pressure is increased?
Give a reason for your answer. [2]
the amount (of ammonia) increases [1] the equilibrium moves to the side (of the equation) with fewer (gaseous) molecules / moles [1]
Why is a temperature much lower than 450 °C not used for the Haber process? [1]
rate of reaction (too) slow [1]
Explain how ammonia is separated from unreacted nitrogen and hydrogen in the Haber process [2]
(gases) cooled [1]
ammonia condensed [1]
State and explain how a decrease in temperature would affect the yield of ammonia at equilibrium [2]
increase yield [1]
because (forward) reaction is exothermic [1]
Name a natural resource from which nitrogen is obtained for the Haber process
air
Name the catalyst used in the Haber process
Iron
Explain why high pressures need to be compromised in the Haber process
too expensive to maintain/requires large amounts of energy
