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national 5 chemistry > Fertilisers > Flashcards

Fertilisers Flashcards

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1
Q

What do plant need from the soil to grow.

A

Plants need nutrients from the soil to grow.

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2
Q

What are the three essential elements required for healthy plant growth?

A

Nitrogen, phosphorus or potassium.

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3
Q

What is the definition for fertilisers?

A

Fertilisers are substances that restore elements, essential for healthy plant growth, to the soil.

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4
Q

What are the main compounds in fertilizers that provide the essential elements?

A

Ammonium salts
Potassium salts
Nitrates
Phosphates

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5
Q

Why are ammonia and nitric acid important compounds and what can be used for?

A

Ammonia and nitric acid are important compounds used to produce soluble, nitrogen-containing salts (ammonium salts and nitrate salts) that can be used in the commercial production of fertilisers.

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6
Q

what are the two types of fertilisers?

A

Fertilisers can be natural, such as compost and manure, or synthetic made commercially in industrial processes.

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7
Q

What is the formula for ammonia?

A

Ammonia has the formula NH3

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8
Q

What is the formula for ammonium?

A

NH4+

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9
Q

Name 5 properties of ammonia?

A 
Ammonia is:
Colourless
less dense than air
A gas with a pungent odour
An alkaline gas
Very soluble in water (the fountain experiment)
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10
Q

What happens when ammonia gas dissolves in water?

A

When ammonia gas dissolves in water it forms a solution of the alkali ammonium hydroxide (sometimes called ammonia solution or aqueous ammonia NH3(aq))

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11
Q

What are the two tests for ammonia?

A

One test for ammonia is it turns damp red litmus blue as it dissolves to form an alkali.
Another test for ammonia gas is to react it with hydrogen chloride gas and it forms white clouds due to tiny particles of the white solid ammonium chloride that forms.

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12
Q

How can ammonia gas be made?

A

Ammonia gas can be made in the lab by reacting any ammonium salt with any alakali.

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13
Q

Name three ammonium salts?

A

Ammonia salts include ammonium chloride, ammonium nitrate and ammonium sulfate.

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14
Q

Name three alkalis which can react with ammonium salts.

A

Ammonium salts will react with an alkali such as sodium hydroxide, potassium hydroxide or calcium hydroxide, to produce ammonia gas,

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15
Q

How is ammonia made industrially in the Haber process?

A

Ammonia is made industrially in the Haber process by the direct combination of nitrogen and hydrogen.

N2 (g) + 3H2( g) ⇌ 2NH3 (g)

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16
Q

How quickly is nitrogen and hydrogen forming ammonia?

A

Nitrogen and hydrogen are forming ammonia as fast as ammonia is breaking up to form nitrogen and hydrogen.

17
Q

Why are the conditions for the Haber process chosen?

A

The conditions for the Haber process are chosen so that ammonia is produced at a commercially viable rate and yield.

18
Q

What are the conditions used in the Haber process?

A 
A moderate temperature is chosen.
An iron catalyst is added.
High pressure is used
Unconverted reactants are recycles though the process. 
The ammonia is constantly removed.
19
Q

In the Haber process why is a moderate temperature chosen?

A

A moderate temperature is chosen because if the temperature is too low the reaction is too slow but if the reaction is too high the ammonia breaks up to form nitrogen and hydrogen.

20
Q

In the Haber process why is an iron catalyst used?

A

An iron catalyst speeds up the reaction. It will be in the form of a gauze or mesh for maximum surface area of contact with reactants.

21
Q

In the Haber process why is high pressure used?

A

High pressure favours the production of ammonia.

22
Q

In the Haber process which unconverted reactants are recycled?

A

Unconverted reactants, nitrogen and hydrogen, are recycled through the process.

23
Q

In the Haber process how and why is the ammonia constantly removed?

A

The ammonia is constantly removed by cooling to condense to a liquid or dissolving in water. This prevents the reverse reaction from occurring.

24
Q

Why is ammonia (NH3) used?

A

Ammonia (NH3) is used to make ammonium salts such as ammonium chloride (NH4CL) which contain the essential element nitrogen and are soluble and therefore very useful in the production of synthetic fertilisers.

25
Q

What is the key ingredient in the industrial preparation of nitric acid?

A

Ammonia is the key ingredient for the industrial preparation of nitric acid.

26
Q

What are the reactions that occur in the Ostwald process?

A

The reactions that occur in this process are summarised below.
Catalytic oxidation of ammonia, This requires a platinum catalyst:
ammonia + oxygen → nitrogen monoxide + water
The nitrogen monoxide formed is reacted with oxygen:
nitrogen monoxide + oxygen → nitrogen dioxide
The nitrogen dioxide made is reacted with water and oxygen to make nitric
acid:
nitrogen dioxide + water + oxygen → nitric acid
HNO3 (aq)

27
Q

What catalyst is used in the Ostwald process?

A

A platinum catalyst.

28
Q

Summarise the Ostwald process.

A

In summary - The Ostwald process uses ammonia, oxygen and water to
produce nitric acid. A platinum catalyst is used in this process.

29
Q

What is nitric acid used for in the Ostwald process?

A

Nitric acid is used to make nitrate (NO3-) fertilisers.

30
Q

What is the key ingredient for synthetic fertilisers?

A

Ammonia gas, NH3 (g), is the key ingredient for making synthetic fertilisers.

31
Q

How is ammonia used to make ammonium salts?

A

Ammonia dissolves in water to form ammonium hydroxide which is used to make ammonium salts.

32
Q

How is ammonia used to make nitrate salts?

A

Ammonia is used to make nitric acid in the Ostwald process which can be used to make nitrate salts.

33
Q

Why do ammonium and nitrate salts make good fertlisers?

A

Ammonia and nitrate salts make good fertilisers as they are soluble compounds and contain the essential element nitrogen.

34
Q

When does a neutralisation occur?

A

A neutralisation reaction occurs when an acid reacts with a base to produce water, a salt is also produced.

35
Q

Can fertilisers be made by neutralisation?

A

Fertilisers can be made by neutralisation using the appropriate base and acid. The salt is the fertiliser.

national 5 chemistry (42 decks)

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