Coordinated Science 2
Fall ILP Days HW
Name:
Date:
Class:
Part 1: Reading and Notes
Directions: Read over and annotate the attached reading (beginning on page 5) and complete the table
and quick questions below.
Process
Raw
Chemical Equations
Essential
Flow Chart/ Diagram
(Product)
Materials
Conditions
Haber Process
(Ammonia)
Contact Process
(Sulfuric Acid)

Write the word equation that summarizes the Haber process:

Describe the sources of the hydrogen and nitrogen required for the Haber process (where do they
come from?).

Why do many fertilizers contain N, P, and K? How can fertilizers cause pollution?

State three uses of sulfur or compounds containing sulfur.

What does the
symbol mean in a chemical equation?
Coordinated Science 2
Fall ILP Days HW
Part 2: Multiple Choice Questions
Circle the correct answers based off of the reading.
(http://www.bbc.co.uk/education/guides/zrg7hyc/test)
1. Which of the following is a common use for ammonia?
A. As a fuel
B. To make plastics
C. To make fertilizers
2. What is the correct formula for ammonia?
A. NH3
B. N2H4
C. HNO3
3. Nitrogen is used in the Haber process to make ammonia. Where does the nitrogen come from?
A. Air
B. Water
C. Crude oil
4. In the Haber process, what temperature is typically used?
A. 50oC
B. 450oC
C. 1000oC
5. In the Haber process, what is the effect of increasing the pressure?
A. Decreases the rate
B. Increases the yield
C. Decreases the cost
6. What catalyst is used in the Haber process?
A. Iron
B. Platinum
C. Nickel
7. As well as ammonia, the mixture leaving the reactor contains unreacted nitrogen and hydrogen which
need to be recycled. How is the ammonia separated from these gases?
A. By filtration
B. By cooling and
C. By heating
compressing
8. What is produced when ammonia is oxidized?
A. Sulfuric acid
B. Hydrochloric acid
C. Nitric acid
9. Which are the 'essential elements' found in many fertilizers?
A. Nitrogen, phosphorus,
B. Carbon, hydrogen,
potassium
oxygen
C. Magnesium, calcium,
sulfur
10. In the contact process, what are the raw materials needed for the production of sulfuric acid?
A. Water, air, sulfur
B. Ammonia, water, oxygen
C. Crude oil, air
Part 3: Cambridge Questions
11. Ammonia is manufactured by the Haber process: N2(g) + 3H2(g) 2NH3(g)
(a) (i) Name the raw materials from which nitrogen and hydrogen are obtained. [2]
(ii) What is the most important use of ammonia? [1]
Coordinated Science 2
Fall ILP Days HW
(b) The following graph shows how the percentage of ammonia in the equilibrium mixture changes
with temperature.
(i) Describe how the percentage of ammonia at equilibrium varies with temperature. [1]
(ii) Suggest how you could increase the yield of ammonia using this information. [2]
12. Ammonia is manufactured by the Haber Process.
The forward reaction is exothermic.
(a) (i) What is the catalyst for this reaction? [1]
(ii) Newer catalysts have been discovered for this process. Using these catalysts, the operating
temperature is lowered from 450°C to 400°C. What is the advantage of using a lower temperature?
Explain your answer. [2]
(b) After passing over the catalyst, the mixture contains 15% of ammonia. It is cooled and the
ammonia liquefies and is separated from the unreacted nitrogen and hydrogen. They are recycled.
(i) How are the gases recycled? [1]
(ii) Only ammonia gas liquefies. Suggest an explanation for this. [1]
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Coordinated Science 2
Fall ILP Days HW
(c) Urea, CO(NH2)2, is one of the fertilizers manufactured from ammonia. Ammonia is heated with
carbon dioxide.
(i) Write a symbol equation for the manufacture of urea. [2]
(ii) Suggest why urea on its own might not be very effective in promoting crop growth. [1]
(d) Give a dot-and-cross diagram showing the arrangement of the valency electrons in one molecule of
ammonia. [3]
Use x to represent an electron from a hydrogen atom.
Use • to represent an electron from a nitrogen atom.
13. Sulfuric acid is made by the Contact process in the following sequence of reactions.
Sulfur sulfur dioxide  sulfur trioxide  sulfuric acid
(a) Describe how sulfur dioxide is made from sulfur. [1]
(b) The equation for a stage of the Contact process is:
2SO2 + O2  2SO3
The percentage of sulfur trioxide in the equilibrium
mixture varies with temperature, as shown at the right.
(i) How does the percentage of sulfur trioxide in
the equilibrium mixture vary as the temperature
increases? Circle the correct answer. [1]
increases
stays the same
decreases
(ii) Is the forward reaction in the equilibrium 2SO2 + O2  2SO3 exothermic or endothermic? Give
a reason for your choice. [2]
(iii) Explain why the temperature used in the Contact process is 450°C. [2]
(iv) Describe how the sulfur trioxide is changed into concentrated sulfuric acid. [2]
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Coordinated Science 2
Fall ILP Days HW
Reading: Ammonia and sulfuric acid
Source: http://www.bbc.co.uk/education/guides/zrg7hyc/revision ;
http://helpmewithigcse.blogspot.com/p/element-sulfur.html
Ammonia is widely used in fertilizers and is manufactured using the Haber process. Sulfuric acid is used
in the manufacture of paints, detergents and fertilizers.
Cambridge Objectives: Annotate the reading for the following information.





Describe the manufacture of sulfuric acid by the Contact process, including essential conditions.
Describe the properties of dilute sulfuric acid as a typical acid.
Describe the need for nitrogen-, phosphorus-, and potassium-containing fertilizers.
Describe the displacement of ammonia from its salts by warming with an alkali.
Describe the essential conditions for the manufacture of ammonia by the Haber process including the
sources of the hydrogen and nitrogen, i.e., hydrocarbons or steam and air.
Ammonia
Ammonia, NH3, is an important raw material in the manufacture of fertilizers. Some ammonia is converted into nitric acid
which itself is used in the manufacture of fertilizers and explosives. Ammonia is also a useful ingredient in some cleaning
fluids.
Ammonia is a vital route by which nitrogen in the air can be made available to plants to enable them to build
protein molecules. Plants cannot use nitrogen directly from the air. They need nitrogen compounds, dissolved in water,
which they absorb through their roots.
Without synthetic, ammonia-based fertilizers, the world would be unable to grow enough food to feed its population.
The Haber process
The raw materials for the process of making ammonia are hydrogen and nitrogen.
Hydrogen is obtained by reacting natural gas (mostly methane) with steam, or from cracking oil fractions.
Nitrogen is obtained from the air. Air is 78 per cent nitrogen and nearly all the rest is oxygen. When hydrogen is burned in air,
the oxygen combines with the hydrogen - leaving nitrogen behind.
In the Haber process, nitrogen and hydrogen react together under these conditions:



a high temperature - about 450°C
a high pressure - about 200 atmospheres (200 times normal pressure)
an iron catalyst
In addition, any unreacted nitrogen and hydrogen are recycled. The reaction is reversible. In a chemical equation, the
symbol is used instead of an ordinary arrow if the reaction is reversible:
This equation summarizes the Haber process:
Stages of the Haber Process
(Refer to diagram on next page)
Stage
1
Stage
2
Stage
3
Stage
4
Stage
5
Having obtained the hydrogen and nitrogen gases (from natural gas and the air respectively), they are
pumped into the compressor through pipes.
The gases are pressurized to about 200 atmospheres of pressure inside the compressor.
The pressurized gases are pumped into a tank containing beds of iron catalyst at about 450°C. In these
conditions, some of the hydrogen and nitrogen will react to form ammonia.
The unreacted nitrogen and hydrogen, together with the ammonia, pass into a cooling tank. The cooling
tank liquefies the ammonia, which can be removed into pressurized storage vessels.
The unreacted hydrogen and nitrogen gases are recycled by being fed back through pipes to pass
through the hot iron catalyst beds again.
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Coordinated Science 2
Fall ILP Days HW
The reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. The mixture is cooled and
compressed, causing the ammonia gas to condense into a liquid. The liquefied ammonia is separated and removed. The
unreacted nitrogen and hydrogen are then recycled back into the reactor.
Uses of ammonia
A major use of ammonia is in the manufacture of fertilizers. Some ammonia is first converted into nitric acid, HNO3.
Production of nitric acid from ammonia
Ammonia is oxidized in the presence of a platinum/rhodium catalyst to form nitrogen monoxide: 4NH3 + 5O2 → 4NO + 6H2O
The nitrogen monoxide is then further oxidized to form nitrogen dioxide: 2NO + O2 → 2NO2
The NO2 is then dissolved into water in the presence of oxygen to form concentrated nitric acid: 4NO2 + 2H2O + O2 → 4HNO3
Production of fertilizers
The most effective fertilizers contain nitrogen because plants need it in order to produce proteins. Phosphorus and potassium
are also essential elements commonly found in fertilizers.
Many fertilizers are ammonium salts. They can also be made from ammonium hydroxide (ammonia solution). If ammonium
hydroxide is used, water is also produced in the neutralization reaction.
Ammonia + nitric acid → ammonium nitrate
Ammonium hydroxide + nitric acid → ammonium nitrate + water
Sulfuric acid – the contact process
The contact process, for making sulfuric acid, is a process which involves a reversible reaction.
The raw materials needed to make sulfuric acid are sulfur, air, and water.
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Coordinated Science 2
Fall ILP Days HW
Stage 1 - making sulfur dioxide
In the first stage of the contact process, sulfur is burned in air to make sulfur dioxide:
This is not a reversible reaction. Sulfur dioxide must not be released as it contributes to acid rain.
Stage 2 - making sulfur trioxide
In the second stage, sulfur dioxide reacts with more oxygen to make sulfur trioxide:
This reaction is reversible. The conditions needed for it are:
 a catalyst of vanadium(V)
 a temperature of around
oxide, V2O5
450°C

a pressure of approximately
2 atmospheres
Stage 3 - making sulfuric acid
In the final stage, sulfur trioxide reacts with water to make sulfuric acid:
This is not a reversible reaction, just like the first stage - (aq) means aqueous or dissolved in water.
Uses and hazards of sulfuric acid
The majority of sulfuric acid that is produced is used to make fertilizers. This is often by reacting the sulfuric acid with
ammonia, or ammonium hydroxide solution, to make ammonium sulfate, (NH4)2SO4.
ammonia + sulfuric acid → ammonium sulfate
ammonium hydroxide + sulfuric acid → ammonium sulfate + water
The other main use of sulfur is to manufacture sulfuric acid, quite possibly the most important industrial chemical. Sulfuric
acid is also used in the production of detergents and paints. Sulfur is rarely found pure in the ground. It is an impurity which
is produced when fossil fuels are burned and it causes acid rain.
Sulfur is also used for sulfur concrete (used in acid factories) which is resistant to acids, vulcanizing rubber (making it
stronger) in tires, etc., and in smaller quantities in matches, fireworks and fungicides, as a sterilizing agent and in medicines.
Sulfur dioxide
Sulfur dioxide is formed when fuels containing sulfur compounds are burned. Sulfur dioxide reacts with water and oxygen in
the air to produce acid rain. This removes sulfur dioxide from the air, but the acid rain corrodes buildings and kills plants.
Sulfur dioxide is a colorless gas, extremely poisonous and has a choking smell. It is produced when sulfur or substances
containing sulfur, such as crude oil or coal, are burned in oxygen gas.
Sulfur dioxide is considered a ‘problem pollutant’ in two main ways. First, it is an acidic oxide that dissolves in water to form
sulfuric acid, which leads to the problem of acid rain. SO2 + H2O  H2SO4. Second, it causes bronchospasm in asthmatics,
therefore considered a respiratory irritant.
Despite this sulfur dioxide is also very useful for the following reasons:
 as a bleaching agent especially in the manufacture of wood pulp for paper
 as a food preservative (by killing bacteria) for meats, etc.
 manufacturing of sulfuric acid (as is elemental sulfur)
Sources of Sulfur
 combustion of fossil fuels with sulfur impurities
 volcanic eruptions
 rotting vegetation
Sulfur is found as an element in the ground and can be obtained by mining and quarrying. Sulfur is also produced during the
refining of petroleum.
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