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The structures of five carbon compounds are shown below.
(a) Answer the following questions about these compounds. Each compound may be used once, more than once or not at all.
(i) Which compound, A, B, C, D or E, is ethanoic acid? ..................................................... [1]
(ii) Which two compounds are saturated hydrocarbons? ...................... and ...................... [1]
(iii) Which compound is the main constituent of natural gas? ......................................... [1]
(iv) Which compound reacts with steam to form ethanol? ................................................ [1]
(v) Which compound is causing concern as a greenhouse gas? .................................... [1]
(vi) Which two compounds are in the same homologous series? ................ and .............. [1]
(b) Deduce the molecular formula for compound C.
...................................................................................................................................................................................... [1]
(c) Complete the symbol equation for the complete combustion of compound A.
$C_3H_8$ + .....$O_2$ $\rightarrow$ $3CO_2$ + .....$H_2O$ [2]
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The diagram shows a bottle of mineral water. The concentration of the ions present in the water is shown on the label. The pH of the water is also shown.
(a) (i) Which positively charged ion is present in the highest concentration?
......................................................................................................................... [1]
(ii) State the name of:
ion X ......................................................................................................................
ion Y ......................................................................................................................
[2]
(iii) Calculate the mass, in mg, of sodium ions in 200 cm$^3$ of mineral water.
.................. mg [1]
(iv) Which one of the following phrases best describes the pH of this mineral water?
Tick one box.
neutral []
strongly acidic []
strongly alkaline []
weakly acidic []
weakly alkaline []
[1]
(b) Describe a test for chloride ions.
test .......................................................................................................
result .................................................................................................
[2]
(c) The mineral water bottle is made of poly(ethene).
Complete the following sentence about poly(ethene) using words from the list below.
atom ionic monomer polymer reactant saturated
Poly(ethene) is a ............................ made by the addition of .............................. units.
[2]
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Rose oil contains 2-phenylethanol.
The structure of 2-phenylethanol is shown below.
(a) On the structure above, draw a ring around the alcohol functional group.
(b) When heated with an alkali, 2-phenylethanol forms styrene.
Styrene is an unsaturated compound.
Describe a test for an unsaturated compound.
test .....................................................................................................................................
result ...................................................................................................................................
(c) Rose petals contain a variety of different coloured pigments.
A student wants to identify these pigments.
(i) She grinds up rose petals with a solvent.
Explain why.
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[2]
(ii) She then filters the solution through some glass wool.
Suggest why she does not use filter paper.
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(d) The student uses the apparatus shown below to identify the different pigments in the mixture.
(i) State the name of this method of separating the pigments.
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[1]
(ii) On the diagram above, draw a spot, ·, to show where the mixture of pigments is placed at the start of the experiment.
[1]
(iii) What is the purpose of the glass cover?
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[1]
(iv) The student also puts four spots of pure pigments, A, B, C and D, onto the filter paper.
The diagram below shows the results of her experiment.
Which of the pigments, A, B, C and D, are present in the rose petals?
.....................................................................................................................................
(e) The solvent used in the experiment is ethanol.
Draw the structure of a molecule of ethanol showing all atoms and bonds.
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A student wants to compare the energy released when different fuels are burned. He measures the increase in temperature of the water in a metal can when the fuels are burned.
(a) What piece of apparatus is missing from the diagram above?
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(b) State two things the student should keep the same when burning each fuel.
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(c) Suggest why the water in the can should be stirred.
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(d) What happens to the reading on the top-pan balance as the fuel burns? Give a reason for your answer.
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(e) The results of burning four fuels, D, E, F and G, are shown in the table below.
[Table_1]
Which fuel produced the greatest temperature rise in the water?
................................................................................................................................................... [1]
(f) The metal can is made of mild steel coated with tin.
(i) Steel is an alloy. What is meant by the term alloy?
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(ii) Why does the tin prevent the steel can from rusting?
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(g) Glass is made from silicon(IV) oxide. Part of the structure of silicon dioxide is shown below.
Which one of the following best describes the structure of silicon dioxide? Tick one box.
giant covalent
giant ionic
simple atomic
simple molecular [1]
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(a) Describe how acids react with metals and with metal oxides.
In your answer:
• refer to a particular metal and metal oxide,
• illustrate your answer with at least one word equation.
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[4]
(b) When metals react with hydrochloric acid, the temperature of the reaction mixture increases.
Which one of the following words best describes this reaction?
Draw a ring around the correct answer.
endothermic exothermic isotopic radioactive
[1]
(c) Uranium is a metal which has several radioactive isotopes. Some of these are used as sources of energy.
State one other use of radioactive isotopes.
........................................................................................................................
[1]
(d) Complete the table below to show the number of protons, neutrons and electrons in two isotopes of uranium.
| isotope | $^{235}_{92} U$ | $^{238}_{92} U$ |
|----------------|----------------|---------------|
| protons | | |
| neutrons | | |
| electrons | | |
[3]
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(a) (i) Describe how the concentration of sodium hydroxide changes with time.
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(ii) Determine the time it took for the concentration of sodium hydroxide to fall to 0.15 mol/dm³.
................................................................................................................................. [1]
(iii) At what time was the reaction complete?
................................................................................................................................. [1]
(iv) On the grid above, draw a line to show how the concentration of sodium hydroxide changes
when the concentration of 1-bromobutane in the reaction mixture is increased.
All other conditions remain the same. [2]
(v) Increasing the concentration of 1-bromobutane increases the rate of this reaction.
Suggest one other way of increasing the rate of this reaction.
................................................................................................................................. [1]
(b) The concentration of aqueous sodium hydroxide can be found by titrating samples of the
reaction mixture with hydrochloric acid.
Describe how you would carry out this titration.
In your answer, refer to:
• a burette,
• a volumetric pipette,
• an acid-base indicator solution.
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(c) Hydrochloric acid is made by dissolving hydrogen chloride gas, HCl, in water.
Draw a dot-and-cross diagram to show a molecule of hydrogen chloride.
Show hydrogen electrons as x.
Show chlorine electrons as •.
................................................................................................................................. [2]
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Fertilisers usually contain compounds of nitrogen, phosphorus and potassium.
(a) Why do farmers use fertilisers? ........................................................................................................................................................................................... [1]
(b) Many fertilisers contain ammonium sulfate. Ammonium sulfate is made by reacting aqueous ammonia with sulfuric acid. What type of chemical reaction is this? ........................................................................................................................................................................................... [1]
(c) Aqueous ammonia reacts with nitric acid to make another compound often found in fertilisers. State the name of this compound. ........................................................................................................................................................................................... [1]
(d) The structure of ammonium sulfate is shown below.
Deduce the simplest ratio of ammonium and sulfate ions in ammonium sulfate. ........................................................................................................................................................................................... [1]
(e) Ammonium salts react with alkalis. For example:
ammonium sulfate + sodium hydroxide → sodium sulfate + ammonia + water
Use this information to explain why adding slaked lime to fields which have fertilisers spread on them may result in loss of nitrogen.
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(f) Many fertilisers contain potassium chloride. When molten potassium chloride is electrolysed, two products are formed. Complete the table below to show the name of the electrodes and the products formed.
[Table_1]
[3]
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(a) A student placed a crystal of iodine in a test tube of solvent. After two minutes, a dense violet colour was observed at the bottom of the test-tube. After three hours, the violet colour had spread throughout the solvent.
Use the kinetic particle theory to explain these observations.
In your answer, refer to:
• the arrangement and motion of the molecules in the iodine crystal,
• the arrangement and motion of the molecules in the solution,
• the names of the processes which are occurring.
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(b) Astatine, At, is below iodine in Group VII of the Periodic Table.
(i) The table shows the states of the Group VII elements at room temperature.
[Table_1]
Use this information to deduce the state of astatine at room temperature.
............................................................................................................................................................... [1]
(ii) Astatine is radioactive. A lot of heat is given off due to this radioactivity. The small samples of astatine that have been isolated are often liquid. Suggest why they are often liquid.
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(iii) Although few compounds of astatine have been made, scientists think that sodium astatide will react with iodine. Complete the equation for this reaction.
$$ I_2 + \ldots\cdot NaAt \rightarrow 2NaI + \ldots\cdot$$
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