1 Three alcohols, A, B and C, are structural isomers with the molecular formula C5H12O.
A, B and C take part in combustion reactions.
Complete the equation for the complete combustion of C5H12O.
C5H12O + ..................................................................................................................................... [2]
2(a) This question is about the chemistry of compounds containing phosphorus.
Phosphine, PH3, is a poisonous gas.
i. Phosphine reacts with oxygen gas to form phosphorus(V) oxide and water.
Write the equation for this reaction.
[1]
ii. Aqueous silver nitrate, AgNO3, is reduced by PH3. The unbalanced equation is
shown below.
Balance the equation and use oxidation numbers to explain why this is a redox reaction.
........ AgNO3 + ........ PH3 + ........ H2O ........ Ag + ........ H3PO3 +........ HNO3
Explanation
[3]
(b) When phosphorus(V) chloride, PCl5, and ammonium chloride are heated together, the compound P3N3Cl6 is
formed, together with HCl gas.
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, P3N3Cl6 has a cyclic structure, like the Kekulé structure of benzene.
i. Write an equation for the reaction of PCl5 and ammonium chloride to form P3N3Cl6.
[1]
ii. Calculate the percentage by mass of P in P3N3Cl6.
Give your answer to 2 decimal places.
percentage by mass of P = ................... % [2]
iii. Suggest one example of evidence that could show that P3N3Cl6 has a Kekulé structure rather than a
delocalised structure.
[1]
iv. In a molecule of P3N3Cl6 all the N and Cl atoms are bonded to P atoms. Suggest a possible structure for a
molecule of P3N3Cl6.
[2]
3 This question is about the analysis of organic compounds.
A student investigates the alkaline hydrolysis of 1-bromopropane as outlined below.
Step 1 The student adds 1-bromopropane to an excess of aqueous potassium hydroxide, KOH(aq), in a
pearshaped flask.
Step 2 A TLC chromatogram is run using propan-1-ol and the reaction mixture.
Step 3 The reaction mixture is refluxed.
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, A TLC chromatogram of the reaction mixture is run every 10 minutes.
The TLC chromatograms are shown below
i. Determine the Rf value of propan–1–ol.
Show your working.
Rf = ................... [1]
ii. Write an equation for the alkaline hydrolysis of 1–bromopropane.
Show structures of organic compounds.
[1]
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, iii. A student investigates the alkaline hydrolysis of 1–chloropropane using the same method as for
1–bromopropane.
Predict, with reasons, how the appearance of the reaction mixture in the chromatogram produced after 20
minutes would be different when 1–chloropropane is used instead of 1–bromopropane.
Suggest why propan–1–ol is run alongside the reaction mixture.
[3]
4 Compound A is a chloride of a Period 3 element.
A student carries out the 2 steps below to find the formula of compound A.
Step 1 The student adds 5.00 × 10–4 mol of compound A to water.
A colourless solution is formed.
Step 2 The colourless solution reacts with exactly 60.0 cm 3 of 2.50 × 10–2 mol dm–3 AgNO3(aq) to form a white
precipitate.
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A, B and C take part in combustion reactions.
Complete the equation for the complete combustion of C5H12O.
C5H12O + ..................................................................................................................................... [2]
2(a) This question is about the chemistry of compounds containing phosphorus.
Phosphine, PH3, is a poisonous gas.
i. Phosphine reacts with oxygen gas to form phosphorus(V) oxide and water.
Write the equation for this reaction.
[1]
ii. Aqueous silver nitrate, AgNO3, is reduced by PH3. The unbalanced equation is
shown below.
Balance the equation and use oxidation numbers to explain why this is a redox reaction.
........ AgNO3 + ........ PH3 + ........ H2O ........ Ag + ........ H3PO3 +........ HNO3
Explanation
[3]
(b) When phosphorus(V) chloride, PCl5, and ammonium chloride are heated together, the compound P3N3Cl6 is
formed, together with HCl gas.
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, P3N3Cl6 has a cyclic structure, like the Kekulé structure of benzene.
i. Write an equation for the reaction of PCl5 and ammonium chloride to form P3N3Cl6.
[1]
ii. Calculate the percentage by mass of P in P3N3Cl6.
Give your answer to 2 decimal places.
percentage by mass of P = ................... % [2]
iii. Suggest one example of evidence that could show that P3N3Cl6 has a Kekulé structure rather than a
delocalised structure.
[1]
iv. In a molecule of P3N3Cl6 all the N and Cl atoms are bonded to P atoms. Suggest a possible structure for a
molecule of P3N3Cl6.
[2]
3 This question is about the analysis of organic compounds.
A student investigates the alkaline hydrolysis of 1-bromopropane as outlined below.
Step 1 The student adds 1-bromopropane to an excess of aqueous potassium hydroxide, KOH(aq), in a
pearshaped flask.
Step 2 A TLC chromatogram is run using propan-1-ol and the reaction mixture.
Step 3 The reaction mixture is refluxed.
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, A TLC chromatogram of the reaction mixture is run every 10 minutes.
The TLC chromatograms are shown below
i. Determine the Rf value of propan–1–ol.
Show your working.
Rf = ................... [1]
ii. Write an equation for the alkaline hydrolysis of 1–bromopropane.
Show structures of organic compounds.
[1]
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, iii. A student investigates the alkaline hydrolysis of 1–chloropropane using the same method as for
1–bromopropane.
Predict, with reasons, how the appearance of the reaction mixture in the chromatogram produced after 20
minutes would be different when 1–chloropropane is used instead of 1–bromopropane.
Suggest why propan–1–ol is run alongside the reaction mixture.
[3]
4 Compound A is a chloride of a Period 3 element.
A student carries out the 2 steps below to find the formula of compound A.
Step 1 The student adds 5.00 × 10–4 mol of compound A to water.
A colourless solution is formed.
Step 2 The colourless solution reacts with exactly 60.0 cm 3 of 2.50 × 10–2 mol dm–3 AgNO3(aq) to form a white
precipitate.
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