No questions found
Element X can undergo the following physical changes.
(a) (i) Give the scientific name for each of the numbered physical changes.
1 ..............................................................................................................................
2 ..............................................................................................................................
3 ..............................................................................................................................
4 .............................................................................................................................. [4]
(ii) Explain why the changes shown are physical changes.
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(iii) One difference between boiling and evaporation is the rate at which the processes occur. State one other difference between boiling and evaporation.
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(b) Describe the separation, arrangement and motion of particles of element X in the solid state.
separation .................................................................................................................
arrangement ..............................................................................................................
motion ...................................................................................................................... [3]
(c) Element X is a Group I metal. It burns in air to form an oxide $X_2O$.
Write a chemical equation for this reaction.
.............................................................................................................................. [2]
551
512
600
Magnesium, calcium, and strontium are Group II elements.
(a) Complete the table to show the arrangement of electrons in a calcium atom.
[Table_1]
[1]
(b) Describe how the arrangement of electrons in a strontium atom is:
(i) similar to the arrangement of electrons in a calcium atom
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(ii) different from the arrangement of electrons in a calcium atom.
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[2]
(c) Calcium reacts with cold water to form two products:
• a colourless gas, P, which 'pops' with a lighted splint
• a weakly alkaline solution, Q, which turns milky when carbon dioxide is bubbled through it.
(i) Name gas P.
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[1]
(ii) Identify the ion responsible for making solution Q alkaline.
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[1]
(iii) Suggest the pH of solution Q.
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[1]
(iv) Write a chemical equation for the reaction of calcium with cold water.
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[2]
(d) Magnesium reacts with chlorine to form magnesium chloride, MgCl$_2$. Magnesium chloride is an ionic compound.
(i) Complete the diagrams to show the electronic structures of the ions in magnesium chloride. Show the charges on the ions.
[3]
(ii) Give three physical properties that are typical of ionic compounds such as MgCl$_2$.
1 ....................................................................................................
2 ....................................................................................................
3 ....................................................................................................
[3]
(e) Aqueous magnesium chloride is added to aqueous silver nitrate. A white precipitate forms.
Write an ionic equation for this reaction. Include state symbols.
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[2]
506
528
519
Sulfur is an important element.
(a) Explain how burning fossil fuels containing sulfur leads to the formation of acid rain.
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(b) Sulfuric acid is manufactured by the Contact process. One step in the Contact process involves a reversible reaction in which sulfur trioxide, $SO_3$, is formed.
(i) Write a chemical equation for this reversible reaction. Include the correct symbol to show that the reaction is reversible.
.............................................................................................................................................. [2]
(ii) State the conditions and name the catalyst used in this reversible reaction.
temperature .........................................................................................................................................
pressure .................................................................................................................................................
catalyst .................................................................................................................................................. [3]
(iii) Describe how the sulfur trioxide formed is converted into sulfuric acid in the next steps of the Contact process.
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(c) Dilute sulfuric acid is used to make salts known as sulfates.
A method consisting of three steps is used to make zinc sulfate from zinc carbonate.
step 1 Add an excess of zinc carbonate to 20 $cm^3$ of 0.4 $mol/dm^3$ dilute sulfuric acid until the reaction is complete.
step 2 Filter the mixture.
step 3 Heat the filtrate until a saturated solution forms and then allow it to crystallise.
(i) Name a suitable piece of apparatus for measuring 20 $cm^3$ of dilute sulfuric acid in step 1.
........................................................................................................................................................... [1]
(ii) State two observations which would show that the reaction is complete in step 1.
1 ..........................................................................................................................................................
2 .......................................................................................................................................................... [2]
(iii) Why is it important to add an excess of zinc carbonate in step 1?
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(iv) What is meant by the term saturated solution in step 3?
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(v) The equation for the reaction is shown.
$ZnCO_3(s) + H_2SO_4(aq) \rightarrow ZnSO_4(......) + H_2O(l) + CO_2(g)$
Complete the equation by inserting the state symbol for zinc sulfate. [1]
(vi) Name another zinc compound which could be used to make zinc sulfate from dilute sulfuric acid using this method.
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(vii) Suggest why this method would not work to make barium sulfate from barium carbonate and dilute sulfuric acid.
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(d) In a titration, a student added 25.0 $cm^3$ of 0.200 $mol/dm^3$ aqueous sodium hydroxide to a conical flask. The student then added a few drops of methyl orange to the solution in the conical flask. Dilute sulfuric acid was then added from a burette to the conical flask. The volume of dilute sulfuric acid needed to neutralize the aqueous sodium hydroxide was 20.0 $cm^3$.
$2NaOH + H_2SO_4 \rightarrow Na_2SO_4 + 2H_2O$
(i) What was the colour of the methyl orange in the aqueous sodium hydroxide?
........................................................................................................................................................... [1]
(ii) Determine the concentration of the dilute sulfuric acid in g/dm³.
• Calculate the number of moles of aqueous sodium hydroxide added to the conical flask.
............................... mol [1]
• Calculate the number of moles of dilute sulfuric acid added from the burette.
............................... mol/dm³
• Calculate the concentration of the dilute sulfuric acid in mol/dm³.
............................... mol/dm³
• Calculate the concentration of the dilute sulfuric acid in g/dm³.
............................... g/dm³ [4]
(e) Iron(II) sulfate decomposes when heated strongly.
$2FeSO_4(s) \rightarrow Fe_2O_3(s) + SO_2(g) + SO_3(g)$
15.20 g of $FeSO_4(s)$ was heated and formed 4.80 g of $Fe_2O_3(s)$.
$[M_r$ $FeSO_4 = 152; M_r$ $Fe_2O_3 = 160]$
Calculate the percentage yield for this reaction.
............................... % [3]
533
562
501
A student investigated the progress of the reaction between dilute hydrochloric acid, HCl, and an excess of large pieces of marble, CaCO₃, using the apparatus shown.
(a) A graph of the volume of gas produced against time is shown.
(i) How does the shape of the graph show that the rate of reaction decreased as the reaction progressed?
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........................................................................................................................................... [1]
(ii) Why did the rate of reaction decrease as the reaction progressed?
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(iii) After how many seconds did the reaction finish?
................................. s [1]
(b) The experiment was repeated using the same mass of smaller pieces of marble. All other conditions were kept the same.
Draw a graph on the grid to show the progress of the reaction using the smaller pieces of marble. [2]
(c) The original experiment was repeated at a higher temperature. All other conditions were kept the same.
Describe and explain, in terms of collisions between particles, the effect of using a higher temperature on the time taken for the reaction to finish.
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520
557
501
(a) Complete the table showing information about the first three alkynes.
[Table_1]
(b) Complete the dot-and-cross diagram to show the electron arrangement in a molecule of ethyne, H−C≡C−H. Show outer shell electrons only.
(c) Compounds in the same homologous series have the same general formula.
(i) Give two other characteristics of members of a homologous series.
1 ...........................................................................................................
2 ...........................................................................................................
[2]
(ii) Use the information in the table in (a) to deduce the general formula of alkynes.
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[1]
(d) Alkynes are unsaturated.
Describe a test for unsaturation.
test ........................................................................................................
result ......................................................................................................
(e) (i) Name an oxidising agent which can be used to oxidise ethanol to ethanoic acid.
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[2]
(ii) Draw the structure of ethanoic acid. Show all of the atoms and all of the bonds.
[1]
(f) Carboxylic acids can be converted into esters.
(i) The ester formed by reacting propanoic acid and methanol has the molecular formula C₄H₈O₂.
Name this ester and draw its structure. Show all of the atoms and all of the bonds.
name of the ester ...............................................................................................
structure of the ester ................................................................................
[2]
(ii) Name another ester with the molecular formula C₄H₈O₂.
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[1]
(g) Polyesters are polymers.
(i) What type of polymerisation is used in the manufacture of polyesters?
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[1]
(ii) Name a polyester.
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[1]
556
587
525
