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</div><h2>HL Paper 1</h2><div class="question">
<p class="p1">According to the Brønsted-Lowry theory, how does each species act in the equilibrium below?</p>
<p>\[{\text{C}}{{\text{H}}_3}{\text{COOH}} + {{\text{H}}_2}{\text{S}}{{\text{O}}_4} \rightleftharpoons {\text{C}}{{\text{H}}_3}{\text{COOH}}_2^ + + {\text{HSO}}_4^ - \]</p>
<p class="p1"><img src="images/Schermafbeelding_2016-09-30_om_13.50.01.png" alt="N09/4/CHEMI/HPM/ENG/TZ0/24"></p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>D</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
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<div class="page" title="Page 11">
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<div class="page" title="Page 12">
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<div class="column">Aqueous solutions of a weak acid and a strong acid of equal concentration are compared. Which statements are correct?</div>
<div class="column"> </div>
<div class="column" style="padding-left: 30px;">I. The weak acid is less dissociated than the strong acid.<br>II. The strong acid reacts with a metal oxide but the weak acid does not.<br>III. The strong acid has greater conductivity than the weak acid.</div>
<div class="column" style="padding-left: 30px;"> </div>
<div class="column">A. I and II only<br>B. I and III only<br>C. II and III only<br>D. I, II and III</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>What is the pH of 1.0 × 10<sup>−3</sup> mol dm<sup>−3</sup> sodium hydroxide, NaOH(aq)?</p>
<p style="text-align: center;"><em>K</em><sub>w</sub> = 1.0 × 10<sup>−14</sup></p>
<p>A. 3</p>
<p>B. 4</p>
<p>C. 10</p>
<p>D. 11</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>D</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which solutions have a pH less than 7?</p>
<p class="p1">I. <span class="Apple-converted-space"> </span>\({\text{N}}{{\text{a}}_2}{\text{C}}{{\text{O}}_3}({\text{aq)}}\)</p>
<p class="p1">II. <span class="Apple-converted-space"> </span>\({\text{[Fe(}}{{\text{H}}_2}{\text{O}}{{\text{)}}_6}{\text{]C}}{{\text{l}}_3}{\text{(aq)}}\)</p>
<p class="p1">III. <span class="Apple-converted-space"> </span>\({{\text{(N}}{{\text{H}}_4}{\text{)}}_2}{\text{S}}{{\text{O}}_4}{\text{(aq)}}\)</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>I and II only</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>I and III only</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>II and III only</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>I, II and III</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>C</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">What is the correct expression for the ionic product constant of water, \({K_{\text{w}}}\)?</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>\({K_{\text{W}}} = \frac{{{\text{[}}{{\text{H}}^ + }{\text{]}}}}{{{\text{[O}}{{\text{H}}^ - }{\text{]}}}}\)</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>\({K_{\text{W}}}{\text{ = }}\frac{{{\text{[}}{{\text{H}}_2}{\text{O]}}}}{{{\text{[}}{{\text{H}}^ + }{\text{][O}}{{\text{H}}^ - }{\text{]}}}}\)</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>\({K_{\text{W}}} = {\text{[}}{{\text{H}}^ + }{\text{]}} + {\text{[O}}{{\text{H}}^ - }{\text{]}}\)</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>\({K_{\text{W}}} = {\text{[}}{{\text{H}}^ + }{\text{][O}}{{\text{H}}^ - }{\text{]}}\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>D</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which of the following is an example of a Lewis acid–base reaction, but not a Brønsted–Lowry acid–base reaction?</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>\({\text{2CrO}}_4^{2 - }{\text{(aq)}} + {\text{2}}{{\text{H}}^ + }{\text{(aq)}} \to {\text{C}}{{\text{r}}_2}{\text{O}}_7^{2 - }{\text{(aq)}} + {{\text{H}}_2}{\text{O(l)}}\)</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>\({\text{Co(}}{{\text{H}}_2}{\text{O)}}_6^{2 + }{\text{(aq)}} + {\text{4HCl(aq)}} \to {\text{CoCl}}_4^{2 - }{\text{(aq)}} + {\text{4}}{{\text{H}}^ + }{\text{(aq)}} + {\text{6}}{{\text{H}}_2}{\text{O(l)}}\)</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>\({\text{N}}{{\text{H}}_3}{\text{(aq)}} + {{\text{H}}^ + }{\text{(aq)}} \to {\text{NH}}_4^ + {\text{(aq)}}\)</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>\({\text{C}}{{\text{H}}_3}{\text{CO}}{{\text{O}}^ - }{\text{(aq)}} + {{\text{H}}_2}{\text{O(l)}} \to {\text{C}}{{\text{H}}_3}{\text{COOH(aq)}} + {\text{O}}{{\text{H}}^ - }{\text{(aq)}}\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p class="p1">B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>What is the pH of a solution in which the hydroxide ion concentration is 1 × 10<sup>−11</sup> mol dm<sup>−3</sup> at 298 K?</p>
<p style="text-align: center;"><em>K</em><sub>w</sub> = 1 × 10<sup>−14</sup> at 298 K</p>
<p>A. 3</p>
<p>B. 7</p>
<p>C. 11</p>
<p>D. 14</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>Which species acts as a Lewis and Brønsted–Lowry base?</p>
<p>A. [Al(H<sub>2</sub>O)<sub>6</sub>]<sup>3+</sup></p>
<p>B. BF<sub>3</sub></p>
<p>C. NH<sub>4</sub><sup>+</sup></p>
<p>D. OH<sup>−</sup></p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>D</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>The table below shows data for the \({{K_{\text{a}}}}\) and \({{\text{p}}{K_{\text{b}}}}\) values for some acids and bases at 298 K.</p>
<p style="text-align: center;"><img src="images/Schermafbeelding_2016-08-24_om_14.49.59.png" alt="N13/4/CHEMI/HPM/ENG/TZ0/28"></p>
<p>Which two formulas represent the weakest acid and the weakest base in the table?</p>
<p>A. HClO and \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{N}}{{\text{H}}_{\text{2}}}\)</p>
<p>B. \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{COOH}}\) and \({\text{N}}{{\text{H}}_{\text{3}}}\)</p>
<p>C. \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{COOH}}\) and \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{N}}{{\text{H}}_{\text{2}}}\)</p>
<p>D. HClO and \({\text{N}}{{\text{H}}_{\text{3}}}\)</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
<p>It was thought “good to mix the data types, \({{\text{p}}{K_{\text{a}}}}\) and \({{K_{\text{a}}}}\)”. This was the fifth hardest question (60.81% correct) with the wrong answers almost equally chosen.</p>
</div>
<br><hr><br><div class="question">
<p>Which species produced by the successive dissociations of phosphoric acid, H<sub>3</sub>PO<sub>4</sub>, are amphiprotic?</p>
<p>A. HPO<sub>4</sub><sup>2−</sup> and PO<sub>4</sub><sup>3−</sup></p>
<p>B. H<sub>2</sub>PO<sub>4</sub><sup>−</sup> and HPO<sub>4</sub><sup>2−</sup></p>
<p>C. H<sub>2</sub>PO<sub>4</sub><sup>−</sup> and PO<sub>4</sub><sup>3−</sup></p>
<p>D. HPO<sub>4</sub><sup>2−</sup> only</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>What is the conjugate base of phenol, \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OH}}\)?</p>
<p>A. \({{\text{C}}_6}{\text{H}}_4^ - \)–OH</p>
<p>B. \({{\text{C}}_6}{{\text{H}}_5}\)–\(\mathop {\text{O}}\limits^ + {{\text{H}}_2}\)</p>
<p>C. \({{\text{C}}_6}{{\text{H}}_5}\)–\({{\text{O}}^ - }\)</p>
<p>D. \({{\text{C}}_6}{\text{H}}_6^ + \)–OH</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>C</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>What are the conjugate acid–base pairs in the following reaction?</p>
<p>\[{\text{HCO}}_3^ - {\text{(aq)}} + {{\text{H}}_2}{\text{O(l)}} \rightleftharpoons {\text{O}}{{\text{H}}^ - }{\text{(aq)}} + {{\text{H}}_2}{\text{C}}{{\text{O}}_3}{\text{(aq)}}\]</p>
<p><img src="images/Schermafbeelding_2016-08-24_om_14.35.14.png" alt="N13/4/CHEMI/HPM/ENG/TZ0/25"></p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>C</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">If \({\text{20 c}}{{\text{m}}^{\text{3}}}\) samples of \({\text{0.1 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) solutions of the acids below are taken, which acid would require a different volume of \({\text{0.1 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) sodium hydroxide for complete neutralization?</p>
<p class="p1">A. <span class="Apple-converted-space"> </span>Nitric acid</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>Sulfuric acid</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>Ethanoic acid</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>Hydrochloric acid</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
<p class="p1">This question on the neutralization of an alkali by various acids proved to be a particularly good discriminator (Discrimination Index 0.68), with many of the weaker students considering that the strength of the acid would affect the amount required.</p>
</div>
<br><hr><br><div class="question">
<p>Which group of three compounds contains only weak acids and bases?</p>
<p><img src="images/Schermafbeelding_2016-08-24_om_14.36.53.png" alt="N13/4/CHEMI/HPM/ENG/TZ0/26"></p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>B</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p class="p1">Which salts will dissolve in water to give solutions with a pH above 7?</p>
<p class="p1">I. <span class="Apple-converted-space"> </span>\({\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}\)</p>
<p class="p1">II. <span class="Apple-converted-space"> </span>\({\text{C}}{{\text{H}}_{\text{3}}}{\text{COONa}}\)</p>
<p class="p1">III. <span class="Apple-converted-space"> </span>\({\text{N}}{{\text{a}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\)</p>
<p class="p1"> </p>
<p class="p1">A. <span class="Apple-converted-space"> </span>I and II only</p>
<p class="p1">B. <span class="Apple-converted-space"> </span>I and III only</p>
<p class="p1">C. <span class="Apple-converted-space"> </span>II and III only</p>
<p class="p1">D. <span class="Apple-converted-space"> </span>I, II and III</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>A</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br><div class="question">
<p>What describes HPO<sub>4</sub><sup>2−</sup>?</p>
<p>A. Amphiprotic but not amphoteric</p>
<p>B. Amphoteric but not amphiprotic</p>
<p>C. Amphiprotic and amphoteric</p>
<p>D. Neither amphiprotic nor amphoteric</p>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question">
<p>C</p>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question">
[N/A]
</div>
<br><hr><br>