12.1. Nitrogen and sulfur
A subsection of Chemistry, 9701, through 12. Nitrogen and sulfur
Listing 10 of 350 questions
Nitrogen, N2, is the most abundant gas in the Earth’s atmosphere and is very unreactive. State why N2 is very unreactive. Magnesium and lithium both form nitrides with N2. These compounds both contain the N3– ion. Write an equation for the reaction of magnesium with N2 to form magnesium nitride. Solid lithium nitride, Li3N, reacts with water according to the following equation. Li3N+ 3H2O3LiOH+ NH3State one observation you would make during this reaction. State the industrial importance of ammonia. One method of producing NH3 is by heating ammonium chloride, NH4Cl, with CaO. 2NH4Cl + CaO 2NH3 + CaCl 2 + H2O Explain why the reaction of NH4Cl with CaO produces ammonia. Three oxides of nitrogen, NO, NO2 and N2O, can be formed under different conditions. Complete the table to give the oxidation numbers of nitrogen in NO and NO2. compound NO NO2 oxidation number of N  NO2 can be formed by different chemical reactions. Write equations for the formation of NO2 by: ● the reaction of N2 with O2 ● the thermal decomposition of magnesium nitrate.  Molecules of N2O can be formed by the reaction between N2 and O2. The bond between the N and O atoms (N O) is a co-ordinate (dative covalent) bond. 2N2+ O22N≡N OThe enthalpy change of reaction for this reaction is +82 kJ mol–1. Calculate the bond enthalpy, in kJ mol–1, of the N O bond. Use relevant data from the Data Booklet to answer this question.  bond enthalpy of the N O bond = kJ mol–1  Nitrosyl chloride, NOCl, is a reactive gas that is sometimes formed when NO reacts with Cl 2. N Cl O nitrosyl chloride δ+ δ– NOCl is a strong electrophile and readily undergoes an addition reaction with alkenes. Complete the diagram to show the mechanism of the electrophilic addition reaction of NOCl with ethene. Include all necessary charges, lone pairs and curly arrows, and the structure of the organic intermediate. N Cl O C H H H H C δ+ δ– C H N O C H H Cl H  
9701_m19_qp_22
THEORY
2019
Paper 2, Variant 2
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Taken together, nitrogen and oxygen make up 99% of the air. Oxygen is by far the more reactive of the two gases, and most of the substances that react with air combine with the oxygen rather than with the nitrogen. State one reason why the molecule of nitrogen, N2, is so unreactive. Despite the apparent lack of reactivity of N2, nitrogen atoms have been found to form bonds with almost all of the elements in the Periodic Table. Lithium metal reacts with nitrogen gas at room temperature to give lithium nitride, Li3N. Magnesium produces magnesium nitride, Mg3N2, as well as magnesium oxide, when heated in air. Calculate the lattice energy of magnesium nitride using the following data, in addition to relevant data from the Data Booklet. enthalpy change value/kJ mol–1 atomisation of Mg+148 total of electron affinities for the change NN3–+2148 enthalpy of formation of Mg3N2–461 lattice energy = kJ mol–1 Lithium reacts readily with nitrogen, and because of this Li3N has been considered as a possible intermediate in the ‘fixing’ of nitrogen to make ammonia-based fertilisers. + Li + H2O N2Li3N NH3 + A Construct an equation for the reaction between Li3N and H2O, and hence identify compound A. Using your knowledge of the Haber process, consider one advantage and one disadvantage of using lithium as a means of fixing nitrogen, rather than the Haber process. advantage of the lithium method disadvantage of the lithium method Another possible advantage of Li3N is that it contains a large percentage by mass of nitrogen. Another fertiliser that contains a large percentage by mass of nitrogen is urea, NH2CONH2. Calculate and compare the percentages by mass of nitrogen in Li3N and NH2CONH2. What class of organic compound is urea? Write an equation for the production of ammonia by the reaction between urea and water. Urea can be applied directly to the soil either before or during the growing of crops. What would be a major disadvantage of using lithium nitride in this way?
9701_s11_qp_41
THEORY
2011
Paper 4, Variant 1
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