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</div><h2>HL Paper 3</h2><div class="specification">
<p class="p1">Nitrogen dioxide and sulfur dioxide are two air pollutants.</p>
</div>
<div class="question">
<p class="p1">Both of these air pollutants also contribute to acid deposition. Outline mechanisms for the formation of \({\text{HN}}{{\text{O}}_{\text{3}}}\) and \({\text{S}}{{\text{O}}_{\text{3}}}\).</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p class="p1"><em>For </em><strong><em>[1 max]</em></strong></p>
<p class="p1">specific effect on certain diseases <em>e.g</em>. relieves nausea in cancer patients to gain mass/weight / relieves glaucoma/Parkinson’s disease symptoms / increases appetite in AIDs patients;</p>
<p class="p1">personal freedom argument / frees police to deal with other/more serious crimes / more taxes / <em>OWTTE</em>;</p>
<p class="p1"><em>No mark for comment such as: cannabis is no more harmful than other legal drugs </em><em>so why should cannabis be different.</em></p>
<p class="p1"><em>Against </em><strong><em>[1 max]</em></strong></p>
<p class="p1">increased risk of lung cancer / respiratory ailments / may suppress body’s immune system;</p>
<p class="p1">may lead to use of harder drugs;</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
<p class="p1">The argument for and against the legalization of cannabis often produced general answers that were rather journalistic in nature with little specific detail provided to score the marks. Usually the last marking point for argument against was scored.</p>
</div>
<br><hr><br><div class="specification">
<p>Acid deposition is a consequence of industrial processes.</p>
</div>
<div class="question" style="padding-left: 20px; padding-right: 20px;">
<p>State what is meant by the term acid deposition.</p>
<div class="marks">[1]</div>
<div class="question_part_label">a.</div>
</div>
<div class="question" style="padding-left: 20px; padding-right: 20px;">
<p>Describe, using equations, the mechanism of acid deposition caused by the oxides of nitrogen, including their initial formation.</p>
<div class="marks">[3]</div>
<div class="question_part_label">b.</div>
</div>
<div class="question" style="padding-left: 20px; padding-right: 20px;">
<p>All shellfish have a calcium carbonate shell. Discuss, including a balanced equation, the long-term effect of acid deposition on these organisms.</p>
<p> </p>
<p>Balanced equation:</p>
<div class="marks">[2]</div>
<div class="question_part_label">c.</div>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question" style="padding-left: 20px;">
<p>process by which acidic (substances) leave atmosphere/return to Earth / <em>OWTTE</em>;</p>
<p><em>Do not allow acid rain.</em></p>
<div class="question_part_label">a.</div>
</div>
<div class="question" style="padding-left: 20px;">
<p><em>Formation:</em></p>
<p>\({{\text{N}}_2}{\text{(g)}} + {{\text{O}}_2}{\text{(g)}} \to {\text{2NO(g)}}/{\text{2NO(g)}} + {{\text{O}}_2}{\text{(g)}} \to {\text{2N}}{{\text{O}}_2}{\text{(g)}}\);</p>
<p><em>Acid deposition: Award </em><strong><em>[2 max] </em></strong><em>for any two of the following.</em></p>
<p>\({{\text{H}}_2}{\text{O(g)}} + {{\text{O}}_3}{\text{(g)}} \to {\text{2HO}} \bullet {\text{(g)}} + {{\text{O}}_2}{\text{(aq)}}/{{\text{H}}_2}{\text{O(g)}} + {\text{O}} \bullet {\text{(g)}} \to {\text{2HO}} \bullet {\text{(g)}}\);</p>
<p>\({\text{HO}} \bullet {\text{(g)}} + {\text{N}}{{\text{O}}_2}{\text{(g)}} \to {\text{HN}}{{\text{O}}_3}{\text{(aq)}}\);</p>
<p>\({\text{HO}} \bullet {\text{(g)}} + {\text{NO(g)}} \to {\text{HN}}{{\text{O}}_2}{\text{(aq)}}\);</p>
<p>\({\text{2N}}{{\text{O}}_2}{\text{(g)}} + {{\text{H}}_2}{\text{O(l)}} \to {\text{HN}}{{\text{O}}_3}{\text{(aq)}} + {\text{HN}}{{\text{O}}_2}{\text{(aq)}}/{\text{2}}{{\text{H}}_2}{\text{O(l)}} + {\text{4N}}{{\text{O}}_2}{\text{(g)}} + {{\text{O}}_2}{\text{(g)}} \to {\text{4HN}}{{\text{O}}_3}{\text{(aq)}}\);</p>
<p><em>Allow radicals represented without dot (if consistent throughout), but penalize inconsistency once only in 17 (b)(ii) and 18 (b).</em></p>
<p><em>Ignore state symbols.</em></p>
<p><em>Award </em><strong><em>[2 max] </em></strong><em>if no free radical used in describing mechanism.</em></p>
<div class="question_part_label">b.</div>
</div>
<div class="question" style="padding-left: 20px;">
<p>shells become thinner as some of the calcium carbonate shell reacts / <em>OWTTE</em>;</p>
<p><em>Accept “dissolving of marine carbonate shells”.</em></p>
<p>\({\text{CaC}}{{\text{O}}_3}{\text{(s)}} + {\text{2HN}}{{\text{O}}_3}{\text{(aq)}} \to {\text{Ca (N}}{{\text{O}}_3}{{\text{)}}_2}{\text{(aq)}} + {{\text{H}}_2}{\text{O(l)}} + {\text{C}}{{\text{O}}_2}{\text{(g)}}/\)</p>
<p>\({\text{CO}}_3^{2 - }{\text{(s)}} + {\text{2}}{{\text{H}}^ + }{\text{(aq)}} \to {\text{C}}{{\text{O}}_2}{\text{(g)}} + {{\text{H}}_2}{\text{O(l)}}/\)</p>
<p>\({\text{CaC}}{{\text{O}}_3}{\text{(s)}} + {\text{2}}{{\text{H}}^ + }{\text{(aq)}} \to {\text{C}}{{\text{a}}^{2 + }}{\text{(aq)}} + {\text{C}}{{\text{O}}_2}{\text{(g)}} + {{\text{H}}_2}{\text{O(l)}}/\)</p>
<p>\({\text{CaC}}{{\text{O}}_3}{\text{(s)}} + {{\text{H}}_2}{\text{S}}{{\text{O}}_4}{\text{(aq)}} \to {\text{CaS}}{{\text{O}}_4}{\text{(aq)}} + {\text{C}}{{\text{O}}_2}{\text{(g)}} + {{\text{H}}_2}{\text{O(l)}}\);</p>
<p><em>Ignore state symbols</em>.</p>
<p><em>Allow equations with H</em><sub><em>2</em></sub><em>SO</em><sub><em>3 </em></sub><em>and HNO</em><sub><em>2</em></sub><em>.</em></p>
<p><em>Do not accept H</em><sub><em>2</em></sub><em>CO</em><sub><em>3 </em></sub><em>instead of H</em><sub><em>2</em></sub><em>O and CO</em><sub><em>2</em></sub><em>.</em></p>
<div class="question_part_label">c.</div>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question" style="padding-left: 20px;">
<p>Candidates confused acid rain with acid deposition in Q18 and the mechanism of acid deposition was patchy. The effect on the carbonate shell of shellfish was understood and most candidates illustrated the reaction with sulfuric acid.</p>
<div class="question_part_label">a.</div>
</div>
<div class="question" style="padding-left: 20px;">
<p>Candidates confused acid rain with acid deposition in Q18 and the mechanism of acid deposition was patchy. The effect on the carbonate shell of shellfish was understood and most candidates illustrated the reaction with sulfuric acid.</p>
<div class="question_part_label">b.</div>
</div>
<div class="question" style="padding-left: 20px;">
<p>Candidates confused acid rain with acid deposition in Q18 and the mechanism of acid deposition was patchy. The effect on the carbonate shell of shellfish was understood and most candidates illustrated the reaction with sulfuric acid.</p>
<div class="question_part_label">c.</div>
</div>
<br><hr><br><div class="specification">
<p class="p1">The concentration of some pollutants in a city was measured over a 24 hour period. The results are shown below.</p>
<p class="p1" style="text-align: center;"><img src="images/Schermafbeelding_2016-10-03_om_15.30.55.png" alt="N09/4/CHEMI/HP3/ENG/TZ0/E3"></p>
</div>
<div class="question">
<p class="p1">Outline the cause of the increase in NO levels between 5 and 8 am.</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p class="p1">NO produced from cars engines increases during morning rush hour;</p>
<p class="p1">NO produced by <span style="text-decoration: underline;">high temperature</span> combination of nitrogen and oxygen (in engine);</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
<p class="p1">In (a), most candidates scored M1, but reference to high temperature was often omitted.</p>
</div>
<br><hr><br><div class="specification">
<p>EDTA is produced by reacting ethane-1,2-diamine with chloroethanoic acid, ClCH<sub>2</sub>COOH.</p>
<p style="text-align: center;"><img src="data:image/png;base64,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"></p>
</div>
<div class="question" style="padding-left: 20px; padding-right: 20px;">
<p>Identify the other product formed.</p>
<div class="marks">[1]</div>
<div class="question_part_label">a.</div>
</div>
<div class="question" style="padding-left: 20px; padding-right: 20px;">
<p>Explain why EDTA, a chelating agent, is more effective in removing heavy metal ions from solution than monodentate ligands.</p>
<div class="marks">[3]</div>
<div class="question_part_label">b.</div>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question" style="padding-left: 20px;">
<p>HCl/hydrogen chloride</p>
<p> </p>
<p><em>Accept “hydrochloric acid”.</em></p>
<p><strong><em>[1 mark]</em></strong></p>
<div class="question_part_label">a.</div>
</div>
<div class="question" style="padding-left: 20px;">
<p>forms four/six/several/multiple coordinate/coordination bonds «to a central metal ion»<br><em><strong>OR</strong></em><br>is a polydentate/tetradentate/hexadentate ligand</p>
<p>forms more stable complex/stronger bonds with central metal ion<br><em><strong>OR</strong></em><br>increases entropy/<em>S</em> by releasing smaller «monodentate ligand» molecules previously complexed</p>
<p>complex ions are much larger «and can be removed easily due to large size of chelate complexes»<br><em><strong>OR</strong></em><br>heavy metal ions trapped inside the ligand/become «biologically» inactive/nontoxic/harmless</p>
<p> </p>
<p><em>Accept “dative «covalent»” for “coordinate/coordination”.</em></p>
<p><em>Do <strong>not</strong> accept just “chelates”.</em></p>
<p><strong><em>[3 marks]</em></strong></p>
<div class="question_part_label">b.</div>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question" style="padding-left: 20px;">
[N/A]
<div class="question_part_label">a.</div>
</div>
<div class="question" style="padding-left: 20px;">
[N/A]
<div class="question_part_label">b.</div>
</div>
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