10. Group 2
A section of Chemistry, 9701
Listing 10 of 275 questions
On the grid below, sketch the trend in the melting points of the Group IV elements. The point for germanium has already been shown. melting point C Si Ge Sn Pb Suggest an explanation of this trend in terms of structure and bonding of the Group IV elements. GeO2, SnO2 and PbO2 are amphoteric oxides. What is meant by the term amphoteric? Construct an equation for the reaction of SnO2 with NaOH. By quoting information from the Data Booklet explain why the reaction between Cr2O7 2–ions and acidified Sn2+ions is feasible. Construct an equation for the reaction in and give any relevant observations. equation observations On heating, germanium(oxide disproportionates to form germanium(oxide and germanium. Describe, using this reaction as an example, what is meant by a disproportionation reaction. Some of the reactions of cyanogen, NC–CN, are similar to those of chlorine, Cl –Cl. On treatment with cold, aqueous sodium hydroxide, cyanogen disproportionates in a similar manner to chlorine. Complete the equation for this reaction. (CN)2 + NaOH → + + Draw a ‘dot-and-cross’ diagram for NC–CN. Show the outer electrons only. At room temperature, phosphorus atoms form P4 molecules rather than P2 molecules. The phosphorus molecule, P4, has a cage-like structure containing only P–P single bonds. All the phosphorus atoms in P4 are trivalent. Suggest a structure for P4. At a temperature of 1200 K P2 and P4 exist in equilibrium in the gas phase. P2 molecules contain the P≡P bond. The average bond energy of P–P is 198 kJ mol–1 while that of P≡P is 489 kJ mol–1. Use the above bond energies to calculate the enthalpy change, ∆H, for the following reaction. 2P2→ P4 When phosphorus(chloride, PCl 5, is reacted with ammonium chloride, NH4Cl, hydrogen chloride gas, HCl, is released and a product with the molecular formula P3N3Cl 6 is formed. Construct an equation for this reaction. P3N3Cl 6 has a cyclic structure containing alternating phosphorus and nitrogen atoms in the ring system. All the nitrogen atoms are trivalent and all the phosphorus atoms are pentavalent. Suggest a structure for P3N3Cl 6.
9701_w15_qp_43
THEORY
2015
Paper 4, Variant 3
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The elements in Group 2 and their compounds show various trends in their physical and chemical properties. The graph below shows the radius values of the atoms and 2+ ions of the elements in Group 2. 0.25 0.20 0.15 0.10 0.05 radius / nm Be Mg Ca Sr element Ba Ra Explain why both lines show a steady increase in the values of the radii down the group. State and explain which line represents the atomic radii and which represents the ionic radii. L is a salt of a Group 2 element M. When L is heated strongly a brown gas is observed and a white solid remains. The white solid dissolves in water to form a colourless solution of the metal hydroxide M(OH)2. Addition of dilute sulfuric acid to this colourless solution produces a dense white precipitate. Identify the anion in salt L. Identify the element M and write an ionic equation for the formation of the white precipitate with sulfuric acid. M = equation Give the formula of salt L and use it to write an equation for the thermal decomposition of salt L. formula of salt L equation Calcium carbonate and calcium hydroxide can both be used in agriculture to neutralise acidic soils. Write ionic equations for the neutralisation of acid by each of calcium hydroxide and calcium carbonate. calcium hydroxide calcium carbonate Suggest and explain why calcium carbonate is a better choice than calcium hydroxide for this purpose in areas of high rainfall. Magnesium reacts with both cold water and steam. Give the formula of the magnesium-containing product of each of these reactions. with cold water with steam
9701_w16_qp_21
THEORY
2016
Paper 2, Variant 1
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The elements in Group 2 and their compounds show various trends in their physical and chemical properties. The graph below shows the radius values of the atoms and 2+ ions of the elements in Group 2. 0.25 0.20 0.15 0.10 0.05 radius / nm Be Mg Ca Sr element Ba Ra Explain why both lines show a steady increase in the values of the radii down the group. State and explain which line represents the atomic radii and which represents the ionic radii. L is a salt of a Group 2 element M. When L is heated strongly a brown gas is observed and a white solid remains. The white solid dissolves in water to form a colourless solution of the metal hydroxide M(OH)2. Addition of dilute sulfuric acid to this colourless solution produces a dense white precipitate. Identify the anion in salt L. Identify the element M and write an ionic equation for the formation of the white precipitate with sulfuric acid. M = equation Give the formula of salt L and use it to write an equation for the thermal decomposition of salt L. formula of salt L equation Calcium carbonate and calcium hydroxide can both be used in agriculture to neutralise acidic soils. Write ionic equations for the neutralisation of acid by each of calcium hydroxide and calcium carbonate. calcium hydroxide calcium carbonate Suggest and explain why calcium carbonate is a better choice than calcium hydroxide for this purpose in areas of high rainfall. Magnesium reacts with both cold water and steam. Give the formula of the magnesium-containing product of each of these reactions. with cold water with steam
9701_w16_qp_23
THEORY
2016
Paper 2, Variant 3
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The elements in Group2 show trends in their properties that are typical of metals. The elements in Group17 show trends in their properties that are typical of non-metals. State and explain the trend in ionisation energy down Group2. State and explain the trend in melting point down Group17. The melting point decreases down Group 2. Explain this trend. Some reactions based on the Group2 metal barium, Ba, are shown. BaXBa(OH)2+ H2Ba(NO3)2+ H2reaction 1 reaction 2 heat in air State the reagent needed for each of reactions 1 and 2. reaction 1 reaction 2 Name X and write an equation for its formation. name equation The Ba(NO3)2, produced by reaction 1, is heated to dryness. The anhydrous solid is then heated strongly and decomposes. Bariumoxide is produced, together with two other products. Identify the two other products of this decomposition reaction and state what would be observed. State what would be observed when excess MgSO4is added to the Ba(OH)2produced in reaction 2. Explain your answer.
9701_w17_qp_22
THEORY
2017
Paper 2, Variant 2
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Questions Discovered
275