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(a) The structures of five substances, A, B, C, D and E, are shown below.
Answer the following questions about these substances.
Each substance may be used once, more than once or not at all.
(i) Which two substances are elements? ............... and ............... [2]
(ii) Which substance has a giant ionic structure? ............... [1]
(iii) Which substance is a product formed when a hydrocarbon is completely burnt in air? ............... [1]
(iv) Which substance, when molten, produces a brown vapour at the anode when electrolysed? ............... [1]
(v) Which substance is used as a lubricant? ............... [1]
(b) Deduce the simplest formula of substance A.
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(c) Calculate the relative molecular mass of substance E.
You must show your working.
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571
506
539
(a) Use ideas about the movement and arrangement of particles to explain why:
• solids have a definite volume and shape,
• liquids have a definite volume but no definite shape,
• gases have no definite volume or shape.
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[4]
(b) The table shows some properties of six substances, A to F, which are either solids or liquids at room temperature.
| substance | melting point / °C | electrical conductivity | solubility in water |
|---|---|---|---|
| A | +3550 | does not conduct in any state | insoluble |
| B | +44 | does not conduct in any state | insoluble |
| C | +1660 | conducts when solid or liquid | insoluble |
| D | +681 | only conducts when in aqueous solution or liquid | soluble |
| E | –39 | conducts when solid or liquid | insoluble |
| F | –11 | does not conduct in any state | insoluble |
(i) Which substance has a giant covalent structure?
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(ii) Which two substances are liquids at room temperature?
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(iii) Which two substances are metals?
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(iv) Which two substances are simple molecules?
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(c) Dry air contains mainly nitrogen, noble gases and oxygen.
(i) Which one of the following shows the correct composition of dry air? Tick one box.
• nitrogen 21%, oxygen 78%, noble gases 1% □
• nitrogen 1%, oxygen 78%, noble gases 21% □
• nitrogen 69%, oxygen 21%, noble gases 10% □
• nitrogen 78%, oxygen 21%, noble gases 1% □ [1]
(ii) Metals can be joined together by high temperature welding. This process is sometimes carried out in the presence of argon. Suggest why welding is carried out in the presence of argon.
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............................................................................................................ [2]
560
531
595
Rhubarb is a plant which has a red stem.
(a) A student separated the pigments in the rhubarb stem by chromatography. He used the apparatus shown below to extract the pigments.
(i) State the name of the piece of apparatus labelled A.
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(ii) Suggest a suitable solvent, other than water, that he could use to extract the pigments.
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(iii) The solution of pigments was not concentrated enough to use for chromatography. Suggest how the student could make the solution more concentrated.
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(b) The student carried out chromatography using the apparatus shown below.
(i) A spot of the pigment mixture was placed at Y. Explain why a spot of the mixture was not placed at Z.
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(ii) Describe how the rest of the procedure was carried out.
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(c) Rhubarb leaves contain ethanedioic acid. The structure of ethanedioic acid is shown below.
(i) On the structure above, put a ring around a carboxylic acid group. [1]
(ii) Deduce the molecular formula of ethanedioic acid.
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(d) A teacher heated ethanedioic acid with concentrated sulfuric acid. The equation for the reaction is:
$$\text{COOH | COOH(s)} \xrightarrow{H_2SO_4} \text{CO(g) + CO}_2\text{(g) + } X$$
(i) Deduce the formula of compound X.
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(ii) At the end of the reaction, the contents of the test-tube contained diluted sulfuric acid only. Explain why.
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(iii) Carbon dioxide is a product of this reaction. State one common source of the carbon dioxide in the atmosphere.
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(iv) Explain why an increase in the concentration of carbon dioxide in the atmosphere is harmful to the environment.
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600
523
523
A mixture of soil and water was shaken and then filtered.
(a) Draw a labelled diagram of the apparatus you would use for separating the insoluble particles of soil from the solution.
[2]
(b) The filtrate was then evaporated.
The table shows the composition and mass of each compound obtained by evaporating the filtrate.
[Table_1]
i) State the name of the compound which contains $K^+$ and $NO_3^-$ ions.
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ii) Write the symbols for the ions present in sodium carbonate.
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iii) Which compound with a singly charged negative ion has the highest mass in the mixture?
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iv) Calculate:
the total mass of all the compounds present in the mixture,
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the percentage of magnesium sulfate by mass in the mixture.
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(c) Calcium carbonate decomposes when heated.
i) Complete the symbol equation for this reaction.
$CaCO_3 \rightarrow CaO +$ ......
[1]
ii) Calcium oxide, $CaO$, reacts with water to form a strongly alkaline solution. Which one of the following pH values is strongly alkaline? Put a ring around the correct answer.
pH 3 pH 7 pH 8 pH 12
[1]
570
505
591
Methanol reacts with excess hydrochloric acid to form chloromethane and water.
methanol + hydrochloric acid \rightarrow chloromethane + water
(a) To which homologous series does methanol belong?
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(b) Complete the structure of methanol below to show its functional group.
[1]
(c) Methanol can be made from synthesis gas which contains carbon monoxide and hydrogen. Synthesis gas is made from methane.
(i) Complete the symbol equation for this reaction.
$CH_4 + H_2O \rightarrow CO + .....H_2$ [1]
(ii) Suggest \textbf{two} hazards associated with the products of this reaction.
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(d) A student investigated the rate of reaction of methanol with hydrochloric acid. The graph below shows how the concentration of hydrochloric acid changes with time.
(i) Describe how the concentration of hydrochloric acid changes with time.
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(ii) Deduce the concentration of hydrochloric acid when the reaction had proceeded for 15 hours.
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(iii) At what time was the reaction just complete?
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(iv) On the grid above, draw a line to show how the concentration of hydrochloric acid changes with time when the reaction takes place at a higher temperature. [2]
(e) Hydrochloric acid is formed when hydrogen chloride gas is dissolved in water. Draw a dot-and-cross diagram to show the electron arrangement in a molecule of hydrogen chloride.
Show only the outer electron shells.
Show hydrogen electrons as x.
Show chlorine electrons as \textbullet.
[2]
599
597
575
Sulfur burns in air to form sulfur dioxide.
(a) (i) Is sulfur dioxide an acidic or basic oxide?
Give a reason for your answer.
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(ii) Sulfur dioxide is an atmospheric pollutant.
Explain why sulfur dioxide in the atmosphere can erode buildings made of limestone.
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(b) Sulfur dioxide reacts with oxygen to form sulfur trioxide.
Sulfur trioxide can be made in the laboratory using the apparatus shown below.
Sulfur trioxide has a melting point of 17°C and a boiling point of 45°C.
(i) Suggest one safety precaution when carrying out this experiment.
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(ii) What is the purpose of the platinum catalyst?
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(iii) Complete the symbol equation for the reaction.
$2SO_2 + .......... \rightarrow .........SO_3$
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(iv) Suggest why the sulfur trioxide is collected in a flask surrounded by ice.
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(v) When 64 g of sulfur dioxide react with excess oxygen, 80 g of sulfur trioxide is formed.
Calculate the mass of sulfur trioxide formed from 160 g of sulfur dioxide.
mass = .......................... g [1]
(c) Sulfur trioxide reacts with water to form sulfuric acid.
A student used the apparatus shown below to determine the concentration of a solution of sodium hydroxide.
(i) Which one of these pieces of apparatus should the student use to put 25.0 cm³ of sodium hydroxide into the flask.
Tick one box.
beaker [ ]
measuring cylinder [ ]
test-tube [ ]
volumetric pipette [ ]
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(ii) How would the student know when the sulfuric acid had neutralised the sodium hydroxide?
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(d) Clean air contains mainly nitrogen, noble gases, oxygen and water vapour.
A teacher left a beaker of concentrated sulfuric acid open to the air for a week. After a week, the concentration of sulfuric acid in the beaker had decreased.
Explain these results by referring to one or more of the substances present in the air.
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519
550
535
(a) Describe the properties of chlorine, bromine and iodine.
In your answer, include the trends in:
• their state,
• their colour,
• their reactivity.
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(b) A molecule of chlorine can be written as $Cl-Cl$.
Which one of the following words describes this molecule?
Put a ring around the correct answer.
diatomic giant ionic monatomic [1]
(c) Draw the electronic structure of a fluorine atom. [2]
(d) The equation below describes the reaction of a halogen with a halide.
| Br \(_2\) + 2KI \(\rightarrow\) I \(_2\) + 2KBr |
546
521
585
