(1) - baffled bee · 2018-09-07 · first he put the 60 known elements in order of their € (1)...

Q1. In 1869, a scientist put the 60 known elements into his periodic table.

Photograph © RIA NOVOSTI/ SCIENCE PHOTO LIBRARY

Draw a ring around the correct answer to complete each sentence.

(1)

Boyle.

Mendeleev.

Newlands.

The scientist who put these elements into a periodic table was

(1)

atomic weight.

boiling point.

electrical conductivity.

First he put the 60 known elements in order of their

(1)

Then he put elements with similar chemical properties in columns, known as

groups.

periods.

rows.

(1)

His periodic table had gaps for elements that were

uncommon.

undiscovered.

unreactive.

(a)

(b)

(c)

(d)

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(e) From 1900 onwards, the modern periodic table was produced.

The modern periodic table is an arrangement of elements in terms of

(1) (Total 5 marks)

their

electronic structures.

neutron numbers.

atomic weights.

Q2. Sodium is in Group 1 of the periodic table.

(a) Here are some statements about sodium.

Which two of these statements are correct?

Tick ( ) two boxes.

(2)

Statement Tick ( )

Sodium is a metal.

Sodium is a halogen.

Sodium forms an ion with a +1 charge.

Sodium forms covalent compounds.

(b) Sodium reacts with water.

A student drew this diagram and wrote the observations A, B, C and D about the reaction between sodium and water.

A The sodium floated and started giving off a gas.

B The sodium melted.

C The piece of sodium became smaller until all the sodium had gone.

D A colourless solution was left.

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Use these observations to answer parts (i) and (ii).

(i) Which observation, A, B, C or D, shows that sodium has a low density? (1)

(ii) Which observation A, B, C or D, shows that the reaction is exothermic? (1)

(iii) What is the name of the gas given off in this reaction?

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(Total 5 marks)

Q3. The periodic table on the Data Sheet may help you to answer this question.

(a) Newlands and Mendeleev both designed periodic tables in which the elements were put in the order of their relative atomic masses.

When the elements are put in this order a few of them are placed incorrectly when compared with a modern periodic table.

(i) Give one example of a pair of elements that would be placed incorrectly if they were in the order of their relative atomic masses.

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(ii) Explain why placing these two elements in the order of their relative atomic masses would not be correct.

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(b) In the modern periodic table the elements are put in order of their atomic (proton) numbers.

Explain how the positions of the elements in the periodic table are linked to the electronic structure of their atoms.

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(Total 4 marks)

Q4. Mendeleev constructed a periodic table in 1869.

In his periodic table:

• most of the elements were put in order of increasing relative atomic mass;

• elements with similar properties were put into groups;

• Mendeleev changed the order of some elements to put them with similar elements;

• spaces were left for elements that Mendeleev thought would be discovered in the future.

One space was in Group 3 between the elements aluminium and indium.

Group 3

Boron

Aluminium

?

Indium

Thallium

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Mendeleev called this undiscovered element ‘eka-aluminium’. This element is now known as gallium. In 1871, he also predicted some of the properties of gallium.

The table shows the properties of aluminium and indium, along with some of the predictions made by Mendeleev for gallium.

Appearance

Metal or non-metal

Boiling point in °C

Density in g per cm3

Relative atomic mass

Aluminium silvery white metal 2467 2.7 27

Predicted properties of gallium

silvery white metal ? ? 68

Indium silvery white metal 2080 7.31 115

(i) Suggest two reasons why other scientists in 1871 did not accept Mendeleev’s periodic table.

Reason 1 .....................................................................................................................

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Reason 2 .....................................................................................................................

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(ii) Suggest why the discovery of gallium in 1875 convinced other scientists that Mendeleev’s table was correct.

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(Total 3 marks)

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Q5. Use the Periodic Table of Elements on the Data Sheet to help you to answer this question.

Francium (Fr) is a very rare element. It is estimated that there is only 25 g of francium in the Earth’s crust. Francium is radioactive and has a half-life of only a few minutes.

Mendeleev predicted the existence of francium in the 1870s but the element was not discovered until 1939.

(a) Explain why Mendeleev was able to predict the existence of francium in the 1870s.

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(b) Suggest why there is not much experimental evidence for the properties of francium.

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(c) (i) If you could react francium with water, how would the reaction compare with that of sodium with water?

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(ii) Explain the reason for your answer.

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(Total 6 marks)

Q6. These are the electronic structures of the atoms of three different elements.

2.8.1 2.8.8 2.8.8.1 element A element B element C

(a) Identify elements A and B.

Element A is ...............................

Element B is ............................... (2)

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(b) (i) Why is element C more reactive than element A?

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(ii) Why is element B unreactive?

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(Total 6 marks)

Q7. Beryllium and calcium are metals in Group 2 of the periodic table.

The diagrams show their electronic structures.

(a) Why do beryllium and calcium have similar chemical properties?

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(b) Calcium is more reactive than beryllium.

Suggest an explanation for this in terms of the electronic structure of the two elements.

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(Total 3 marks)

Q8. The following article appeared recently in the Manchester Gazette.

(a) Group 1 metals are stored under oil.

Suggest why.

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Sodium Drum Blaze Scare

A 20 litre drum containing sodium burst into flames when it reacted violently with rainwater at a Manchester factory. It is believed that the sodium, which is normally stored under oil, had been accidentally left outside with the lid off.

A factory worker put out the blaze before the fire services arrived, and a leading fire fighter said, “It was fortunate that potassium wasn’t involved as it would have reacted more violently and exploded. These Group 1 alkali metals can be very dangerous”.

(b) Balance the equation which represents the reaction between sodium and water.

Na + H2O → NaOH + H

2

(1)

(c) Explain why the Group 1 metals are called the alkali metals.

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(d) Explain, in terms of electrons, why potassium reacts more violently than sodium.

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(Total 6 marks)

Q9. Fluorine is more reactive than chlorine. Fluorine reacts with most elements in the Periodic Table. However, fluorine does not react with argon.

Atomic numbers: F 9; Cl 17; Ar 18.

(a) To which group of the Periodic Table do fluorine and chlorine belong?

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(b) (i) Give one use for argon.

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(ii) Explain why the noble gas argon is unreactive.

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(c) (i) Give one use for chlorine.

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(ii) Draw the electron arrangement of a chlorine atom.

(2)

(iii) Explain why fluorine is more reactive than chlorine.

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(Total 10 marks)

Q10. The table shows information about the halogens in Group 7 of the periodic table.

Name of halogen Melting point in °C Boiling point in °C Electronic structure

Fluorine –220 –188 ...............................

Chlorine –101 –35 2,8,7

Bromine –7 +58 2,8,18,7

Iodine +114 +183 2,8,18,18,7

(a) Use information from the table to help you to answer these questions.

(i) Name one halogen that is a solid at 25 °C.

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(ii) Name one halogen that is a gas at 25 °C.

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(iii) Use the periodic table on the Data Sheet to help you to work out the correct electronic structure for fluorine. Write your answer in the table above.

(1)

(iv) Use the periodic table on the Data Sheet to name one Group 7 element that is not shown in the table above.

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(b) A teacher demonstrated the reactivity of the halogens to some students. Halogen vapour was passed over heated iron wool in a fume cupboard.

The teacher’s observations are shown in the table below.

Observations

During the reaction After the reaction

Bromine The iron wool glowed A red–brown solid had been produced

Chlorine The iron wool glowed brightly A dark brown solid had been produced

Iodine The iron wool did not glow A black solid had been produced

(i) What is the order of reactivity of these three halogens?

Order of reactivity: most reactive halogen 1 ......................................

2 ......................................

least reactive halogen 3 ...................................... (1)

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(ii) Explain how you used the teacher’s observations to decide your order of reactivity.

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(Total 7 marks)

Q11. The diagram shows some of the elements in Groups I and 7 of the Periodic Table.

(a) The elements in Group 1 have similar chemical properties.

Describe one chemical reaction which shows that lithium, sodium and potassium react in the same sort of way. You should say what you would react them with and what substances would be produced.

• What you would react them with

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• Substances produced

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(b) All the elements in Group 7 react with hydrogen.

Fluorine reacts in the dark, explosively, at very low temperatures. Chlorine reacts explosively in sunlight, at room temperature. Bromine, in light, only reacts if heated to about 200°C.

Suggest the conditions needed for hydrogen and iodine to react. Give reasons for your answer.

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(c) Hydrogen and chlorine react to produce hydrogen chloride. Balance the symbol equation for the reaction.

H2 + Cl

2 → HCl

(1)

(d) Use your understanding of atomic structure to explain the trend in reactivity in the Group 7 elements.

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(Total 8 marks)

Q12. Read the information about the periodic table.

In 1869 Dimitri Mendeleev classified the elements by first putting them in order of their atomic weights.

Then he arranged them in a table, so that elements with similar properties and reactions were in columns known as Groups.

He also left gaps in his table for undiscovered elements.

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Use the modern periodic table on the Data Sheet to help you to answer these questions.

(a) Some elements were not placed in order of increasing atomic weights.

In terms of properties, suggest why potassium (atomic weight 39) should be placed after argon (atomic weight 40).

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(b) Some scientists thought that Mendeleev’s table was not correct.

Suggest why, by referring to the elements in Group 4.

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(c) In the 1890s a new group of elements (Group 0) was discovered.

Suggest why they were easily fitted into Mendeleev’s table.

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(Total 3 marks)

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Q13. Read the information about the development of the periodic table and answer the questions that follow.

Reproduced courtesy of the library and information centre Royal Society of Chemistry

John Newlands was one of the first chemists to arrange the known elements in order of increasing atomic mass. In 1866, he put forward the Law of Octaves. He suggested that there was a repeating pattern of elements with similar chemical properties every eighth element, just like the eighth note of an octave of music. A version of his periodic table is shown below.

H Li G Bo C N O

F Na Mg Al Si P S

Cl K Ca Cr Ti Mn Fe

Co, Ni Cu Zn Y In As Se

Br Rb Sr Ce, La Zr Di, Mo Ro, Ru

Pd Ag Cd U Sn Sb Te

I Cs Ba, V Ta W Nb Au

Pt, Ir Os Hg Tl Pb Bi Th

However, other chemists did not accept Newlands’ ideas. It was not until much later that his contribution to the development of the modern periodic table was recognised.

The modern periodic table on the Data Sheet may help you to answer these questions.

(a) What is the modern symbol for the element ‘Bo’? ........................................................... (1)

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(b) Describe one piece of evidence to support the Law of Octaves.

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(c) Suggest two reasons why other chemists did not accept Newlands’ ideas.

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(d) The alkanes are a series of hydrocarbons with similar chemical properties. They have the general formula C

nH

2n+2.

Suggest why the alkanes do not appear in the periodic table.

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(Total 6 marks)

Q14. Some students slowly add solution Y to solution X.

The graph shows what happens to the pH of the solution in the beaker as they do this.

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(a) Choose words from this list to complete the sentences below.

acidic alkaline neutral

At point A on the graph the solution in the beaker is ...............................................

At point B on the graph the solution in the beaker is ...............................................

At point C on the graph the solution in the beaker is ............................................... (2)

(b) Describe, as fully as you can, what happens to the pH of the mixture as solution Y is slowly added.

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(Total 7 marks)

Q15. Chlorine and bromine are important Group 7 elements.

(a) Explain why chlorine is added to drinking water.

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(b) Describe what you would see when bromine water is added to an unsaturated organic compound.

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(c) Bromine can be extracted from seawater. The dissolved bromide ions are reacted with chlorine. Bromine and chloride ions are formed.

(i) Complete and balance the equation below, which represents the reaction between chlorine and bromide ions.

Cl2 + 2Br– → ......................... + .........................

(1)

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(ii) Describe what you see when chlorine is added to a solution containing bromide ions.

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(d) In terms of electronic structure:

(i) state why bromine and chlorine are both in Group 7

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(ii) explain why bromine is less reactive than chlorine.

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(e) What is the result of adding acidified silver nitrate solution to a solution containing:

(i) chloride ions

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(ii) bromide ions?

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(Total 10 marks)

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Q16. In 1916 a ship was sunk by a German submarine. The ship was carrying bottles of champagne. The wreck was discovered in 1997 and the champagne was brought to the surface and analysed.

The diagram shows the apparatus used to find the amount of acid in 25 cm3 of the champagne.

(a) Choose the correct words from the box to name apparatus X and Y.

(i) Apparatus X is a ................................................................................................ (1)

beaker burette conical flask measuring cylinder

(ii) Apparatus Y is a ................................................................................................ (1)

(b) Sodium hydroxide solution was added to this champagne until substance Z showed that the reaction was complete. The volume of sodium hydroxide used was recorded. The result was used to calculate the amount of acid present.

Complete these sentences by drawing a ring around the correct answer.

(1)

(i) Substance Z is

a catalyst

a conductor

an indicator

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(1)

(ii) The reaction was complete when substance Z

changed colour

formed a gas

gave a precipitate

(1)

(iii) The name of this method of analysis is

distillation

filtration

titration

(c) 250 cm3 of this champagne were found to contain 1 g of acid.

Calculate the mass of acid in 750 cm3 of this champagne.

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Mass = .......................................... g (2)

(d) (i) Which one of the following ions makes champagne acidic?

Draw a ring around your answer.

chloride hydrogen sodium (1)

(ii) The acid in champagne is a weak acid.

Complete this sentence by drawing a ring around the correct answer.

(1) (Total 9 marks)

The word weak means that the acid

has a low boiling point

is dilute

is partially ionised

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Q17. A student carried out a titration to find the concentration of a solution of sulphuric acid. 25.0

cm3 of the sulphuric acid solution was neutralised exactly by 34.0 cm3 of a potassium hydroxide

solution of concentration 2.0 mol/dm3. The equation for the reaction is:

2KOH(aq) + H2SO

4(aq) → K

2SO

4(aq) + 2H

2O(l)

(a) Describe the experimental procedure for the titration carried out by the student.

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(b) Calculate the number of moles of potassium hydroxide used.

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Number of moles = ....................................... (2)

(c) Calculate the concentration of the sulphuric acid in mol/dm3.

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Concentration = .................................. mol/dm3

(3) (Total 9 marks)

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Q18. The label shows the ions present in the bottle of spring water. This water is temporarily hard.

(a) Name the compound that would be present in the greatest amount if this water were evaporated to dryness.

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(b) (i) What is hard water?

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(ii) State one advantage of hard water.

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(c) Describe an experiment that would show that this water is temporarily hard.

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(d) This hard water may be softened as shown.

What name is given to this process?

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(Total 10 marks)

Q19. In some parts of the world the water is hard, but in other parts the water is soft.

(i) Name an ion that causes water to be hard.

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(ii) Describe how these ions get into the water.

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(iii) Sodium carbonate makes hard water soft.

Explain how.

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(Total 5 marks)

Q20. Water is a natural resource.

(a) Water in some parts of the UK is hard, but in other parts of the UK it is soft.

Draw a ring around the correct answer to complete each sentence.

(1)

condense

(i) Water becomes hard because ions in rocks dissolve into the water

evaporate

(1)

calcium

(ii) Hardness in water is caused by hydrogen ions

sodium

(b) There are two types of hard water, permanent hard water and temporary hard water.

Draw a straight line from each statement to the correct type of water.

(2)

Statement Type of water

Permanent hard water

Easily makes a lather with soap

Temporary hard water

Can be made soft by boiling

Soft water

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(c) Water of the correct quality is essential for life.

In many parts of the world the water used for drinking contains solid particles and harmful bacteria.

Suggest two methods that could be used to improve the quality of this water.

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(Total 6 marks)

Q21. In 1916, during the First World War, a German U-boat sank a Swedish ship which was carrying a cargo of champagne. The wreck was discovered in 1997 and the champagne was brought to the surface and analysed.

(a) 25.0 cm3 of the champagne were placed in a conical flask.

Describe how the volume of sodium hydroxide solution needed to react completely with the weak acids in 25.0 cm3 of this champagne can be found by titration, using phenolphthalein indicator.

Name any other apparatus used.

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(b) The acid in 25.0 cm3 of the champagne reacted completely with 13.5 cm3 of sodium hydroxide of concentration 0.10 moles per cubic decimetre.

Calculate the concentration in moles per cubic decimetre of acid in the champagne.

Assume that 1 mole of sodium hydroxide reacts completely with 1 mole of acid.

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Concentration = ......................... moles per cubic decimetre (2)

(c) Is analysis by titration enough to decide whether this champagne is safe to drink?

Explain your answer.

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(d) The graph shows how the pH of the solution changes during this titration.

Phenolphthalein is the indicator used in this titration. It changes colour between pH 8.2 and pH 10.0.

Methyl orange is another indicator. It changes colour between pH 3.2 and pH 4.4.

Suggest why methyl orange is not a suitable indicator for this titration.

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(Total 9 marks)

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Q22. This label has been taken from a bottle of household ammonia solution.

Household ammonia is a dilute solution of ammonia in water. It is commonly used to remove grease from ovens and windows.

(a) The amount of ammonia in household ammonia can be found by titration.

25.0 cm3 of household ammonia is placed in a conical flask. Describe how the volume of dilute nitric acid required to neutralise this amount of household ammonia can be found accurately by titration. Name any other apparatus and materials used.

To gain full marks you should write down your ideas in good English. Put them into a sensible order and use correct scientific words.

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(b) In an experiment, it was found that 25.0 cm3 of household ammonia was neutralised by 20.0 cm3 of dilute nitric acid with a concentration of 0.25 moles per cubic decimetre.

The balanced symbol equation which represents this reaction is

NH3(aq) + HNO

3(aq) → NH

4NO

3(aq)

Calculate the concentration of the ammonia in this household ammonia in moles per cubic decimetre.

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Concentration = ............................. moles per cubic decimetre (2)

(c) The salt, ammonium nitrate, is formed in this reaction.

Describe, and give the result of, a chemical test which shows that ammonium nitrate contains ammonium ions.

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(Total 8 marks)

Q23. Water is a natural resource. Drinking water in some parts of the UK is soft, but in other parts drinking water is hard. Calcium ions in water cause water to be hard.

There are two types of hard water, permanent hard water and temporary hard water.

• Permanent hard water can be caused by calcium sulfate (CaSO4) dissolved in the water

• Temporary hard water can be caused by calcium hydrogencarbonate (Ca(HCO3)

2)

dissolved in the water

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(a) Temporary hard water causes the formation of scale on heating elements.

Photograph © Steve Gorton / Getty Images

(i) Explain how scale forms on heating elements.

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(ii) Suggest why scale on heating elements causes problems.

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(b) Permanent hard water can be softened.

(i) Explain how adding sodium carbonate (Na2CO

3) softens permanent hard water.

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(ii) Explain how a water filter containing carbon, silver and ion exchange resin softens permanent hard water.

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(Total 7 marks)

Q24. Drain Buster is used to clear and degrease drains. Sodium hydroxide is the main chemical substance in Drain Buster.

(a) A student planned an experiment to find the concentration of the sodium hydroxide solution in Drain Buster.

The teacher had to dilute the Drain Buster before the student could use it.

Explain why.

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(b) In this question you will get marks on using good English, organising information clearly and using specialist terms where appropriate.

The student wanted to find the volume of hydrochloric acid that reacts with a known volume of diluted Drain Buster.

Describe how the student could do this by titration. In your description you should include: • the names of pieces of apparatus used • the names of the substances used • a risk assessment

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(Total 8 marks)

Q25. The Haber process is used to make ammonia NH3.

The table shows the percentage yield of ammonia at different temperatures and pressures.

PRESSURE (ATMOSPHERES)

PERCENTAGE (%) YIELD OF AMMONIA AT 350°C

PERCENTAGE (%) YIELD OF AMMONIA AT 500°C

50 25 5

100 37 9

200 52 15

300 63 20

400 70 23

500 74 25

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(a) (i) Use the data in the table to draw two graphs on the grid below. Draw one graph for a temperature of 350°C and the second graph for a temperature of 500°C. Label each graph with its temperature.

(4)

(ii) Use your graphs to find the conditions needed to give a yield of 30% ammonia.

................................ °C and .............................. atmospheres (1)

(iii) On the grid sketch the graph you would expect for a temperature of 450°C. (1)

(b) (i) This equation represents the reaction in which ammonia is formed.

N2(g)

+ 3H2(g)

2NH3(g)

+ heat

What does the symbol in this equation tell you about the reaction?

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(ii) Use your graphs and your knowledge of the Haber process to explain why a temperature of 450°C and a pressure of 200 atmospheres are used in industry.

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(c) (i) Ammonium nitrate is one type of artificial fertiliser. Calculate the relative formula mass of ammonium nitrate NH

4NO

3.

(Relative atomic masses: H = 1, N = 14, O = 16.)

...........................................................................................................................

........................................................................................................................... (1)

(ii) Use your answer to part (c)(i) to help you calculate the percentage by mass of nitrogen present in ammonium nitrate NH

4NO

3.

...........................................................................................................................

........................................................................................................................... (2)

(Total 15 marks)

Q26. The monomer chloroethene is made from ethene in a two-stage process,

(a) The first stage is to convert ethene to 1,2-dichloroethane.

2C2H

4(g) + 4HC1(g) + O

2(g) 2C

2H

4Cl

2(g) + 2H

2O(g)

ethene 1,2-dichloroethane

State and explain the effect of increasing the pressure on:

(i) the yield of 1,2-dichloroethane;

...........................................................................................................................

........................................................................................................................... (2)

(ii) the rate of reaction.

...........................................................................................................................

........................................................................................................................... (2)

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(b) In the second stage 1,2-dichloroethane is converted into chloroethene.

C2H

4C1

2 → C

2H

3C1 + HCl

This reaction is a thermal decomposition.

Suggest what would need to be done to decompose 1,2-dichloroethane.

......................................................................................................................................

...................................................................................................................................... (1)

(Total 5 marks)

Q27. Methanol is a fuel that is used in some racing cars instead of petrol.

Methanol can be made from carbon monoxide and hydrogen. The equation for this reaction is shown below.

CO(g) + 2H2(g) CH

3OH(g)

The forward reaction is exothermic.

(a) A high pressure (between 50 and 100 atmospheres) is used in this process.

Explain why the highest equilibrium yield of methanol is obtained at high pressure.

.....................................................................................................................................

..................................................................................................................................... (1)

(b) The temperature used in this process is about 250 °C.

It has been stated that, ‘the use of this temperature is a compromise between the equilibrium yield of product and the rate of reaction’.

Explain this statement.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 4 marks)

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Q28. Ammonia is used in the production of fertilisers. The flow diagram shows the main stages in the manufacture of ammonia.

Study the flow diagram and then answer the questions.

(a) (i) Name gas X and name gas Y.

Gas X is ............................... Gas Y is ............................... (2)

(ii) Draw a ring around the correct answer to complete the sequence.

(1)

cooled

In the condenser the mixture is heated to separate ammonia as a liquid.

oxidised

(b) The ammonia is separated as a liquid from the unreacted gases.

Suggest two reasons why the unreacted gases are recycled.

........................................................................................................................

........................................................................................................................

........................................................................................................................

........................................................................................................................ (2)

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(c) The graph shows the percentage of ammonia made at different temperatures and pressures.

Study the graph and then answer the questions.

(i) Draw a ring around the correct answers to complete the sentence.

To make the greatest percentage yield of ammonia

(2)

the temperature should be

low

medium

high

and the pressure

should be

low

medium

high

(ii) What is the percentage yield of ammonia at a temperature of 450°C and at a pressure of 200 atmospheres?

................................................ % (1)

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(iii) Ammonia is often made at a temperature of 450°C and at a pressure of 200 atmospheres.

Suggest two reasons why it is economical to make ammonia using these conditions.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

(Total 10 marks)



(a) What is the purpose of the iron in the reactor?

........................................................................................................................

........................................................................................................................ (1)

(b) In the reactor the equation to produce ammonia is:

N2(g) + 3H

2(g) 2NH

3(g)

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(i) The equation shows that the reaction is reversible.

Explain how the reaction reaches an equilibrium.

...............................................................................................................

............................................................................................................... (1)

(ii) The best yield of ammonia at equilibrium is produced at a low temperature.

Explain why.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

(iii) The best yield of ammonia at equilibrium is produced at a high pressure.

Explain why.

...............................................................................................................

............................................................................................................... (1)

(Total 5 marks)

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(a) What is the purpose of the iron in the reactor?

........................................................................................................................

........................................................................................................................ (1)

(b) In the reactor the equation to produce ammonia is:

(i) The equation shows that the reaction is reversible.

Explain how the reaction reaches an equilibrium.

...............................................................................................................

............................................................................................................... (1)

N2(g) + 3H

2(g) 2NH

3(g)

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(ii) The best yield of ammonia at equilibrium is produced at a low temperature.

Explain why.

...............................................................................................................

...............................................................................................................

...............................................................................................................

............................................................................................................... (2)

(iii) The best yield of ammonia at equilibrium is produced at a high pressure.

Explain why.

...............................................................................................................

............................................................................................................... (1)

(Total 5 marks)

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(1) - baffled bee · 2018-09-07 · first he put the 60 known elements in order of their € (1)...

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