CAIE
Chemistry
(9701)
Questions & Answers
The solubility of the Group 2 hydroxides increases down the group. Explain this trend.
The solubility of Be(OH) in water is 2.40 × 10
Write an expression for the solubility product, K , of Be(OH) and state its units. units =
Calculate the numerical value of K for Be(OH) =
Be(OH) is soluble in aqueous solutions containing an excess of hydroxide ions and forms the complex ion [Be(OH)
Define the term complex ion.
Draw a three-dimensional diagram to show the structure of the complex ion [Be(OH) Name the shape of the [Be(OH) complex ion. shape
(i) Explain why transition elements can form complex ions.
Complete Table 1.1 to show the coordination number of each metal ion, and the shapes and overall polarities of the complex ions listed. Table 1.1 complex ion shape coordination number polar or non-polar cis-[Pt(HNCH ]square planar [Ag(NH non-polar [Fe(C
(i) Define stability constant, K stab
Nickel can form complexes with the ligands en, HNCH , and tn, HNCH equilibrium 1 [Ni(H + 3en [Ni(en) + 6HO K stab = 6.76 × 10 equilibrium 2 [Ni(H + 3tn [Ni(tn) + 6HO K stab = 1.86 × 10 Construct an expression for the stability constant, K stab , for equilibrium 1. State the units for K stab stab units =
Describe what the K stab values indicate about the position of equilibrium for equilibrium 1 and 2. Use the K stab values to deduce which complex, [Ni(en) or [Ni(tn) , is more stable. [Total: 16]
Explain why transition elements have variable oxidation states.
Sketch the shape of a 3d orbital.
Explain why transition elements form coloured compounds.
Aqueous solutions of copper( II) salts contain [Cu(H ions. Equilibrium 3 and equilibrium 4 show two reactions of these ions. equilibrium 3 [Cu(H
+ 2OH
Cu(OH)
+ 6H O
equilibrium 4 [Cu(H
+ 4NH
[Cu(NH
+ 4H O(l)
State the colour of Cu(OH)
and [Cu(NH
colour of Cu(OH)
colour of [Cu(NH
Use Le Chatelier's principle to explain why a precipitate is formed when NaOH(aq) is added dropwise to [Cu(H
There are two possible stereoisomers with the formula [Cu(NH Draw three-dimensional diagrams to show the two stereoisomers. Cu Cu [2] [Total: 9]
(i) Define first electron affinity.
The first electron affinity of an atom is usually an exothermic process, whereas the second electron affinity is an endothermic process. Suggest why.
Describe the general trend in first electron affinities for Cl, Br and I. Explain your answer.
Table 3.1 shows energy changes to be used in this question and in
. Table 3.1 standard enthalpy change of atomisation of zinc +131 first ionisation energy of zinc +906 second ionisation energy of zinc +1733 standard enthalpy change of formation of ZnI
208 lattice energy, , of zinc iodide, ZnI
2605 first ionisation energy of iodine +1008 second ionisation energy of iodine +1846 I-I bond energy +151 enthalpy change of sublimation of iodine, I
+62 Calculate the first electron affinity for iodine. Use relevant data from Table 3.1 in your working. It may be helpful to draw a labelled energy cycle. Show all working.
Predict how of CdI
differs from of ZnI
Table 3.2 of CdI
is less negative than of ZnI
of CdI
is the same as of ZnI
of CdI
is more negative than of ZnI
Explain your answer. [Total: 9]
Calcium carbonate decomposes on heating. CaCO
, for this reaction at various temperatures. Table 4.1 1050 9.9 1085 4.3 1120 -1.3 1148 -5.8 1176 -10.3 , for this reaction remain constant over this temperature range. against T on the grid. 12.5 10.0 7.5 5.0 2.5 0.0 -2.5 -5.0 -7.5 -10.0 -12.5 1040 1060 1080 1100 1120 1140 1160 1180 1200 / kJ mol [2] for this reaction. Show all working.
Group 1 hydrogencarbonates, MHCO , decompose on gentle heating to give the corresponding metal carbonate, carbon dioxide and water vapour.
Write an ionic equation for the decomposition of the hydrogencarbonate ion.
The thermal stability of Group 1 hydrogencarbonates increases down the group. Suggest an explanation for the trend in thermal stability of the Group 1 hydrogencarbonates.
The buffer system in seawater contains a mixture of HCO - and H2CO equilibrium 5 H + H HCO + H
Define a buffer solution.
Construct two equations to show how equilibrium 5 acts as a buffer solution.
The [HCO ] ratio in a sample of seawater is 14.1. Calculate the pH of this sample. [pK: H , 6.35] pH = [3] [Total: 14]
Complete Table 5.1 to predict the substance liberated at each electrode during electrolysis of the indicated electrolyte with inert electrodes. Table 5.1 electrolyte substance liberated at the anode substance liberated at the cathode PbBr
Cu(NO
An electrolytic cell is set up to determine a value for the Avogadro constant, L. The electrolyte is dilute sulfuric acid and both electrodes are copper.
State the relationship between the Faraday constant, F, and the Avogadro constant, L.
Use the experimental information in
and data from the table on page 23 to calculate a value for the Avogadro constant, L. Show all working. Avogadro constant, L = [4] [Total: 8]
The reagent and conditions required for the nitration of benzene, benzoic acid and phenol are shown in Table 6.1. Table 6.1 compound reagents and conditions for nitration benzene concentrated HNO catalyst benzoic acidconcentrated HNO catalyst phenol dilute HNO Concentrated HNO reacts with concentrated H to generate the electrophile NO
Complete Fig. 6.1 to show the mechanism of the reaction between benzene and NO Include all relevant curly arrows and charges.
Write an equation to show how H is regenerated.
Draw the major products from the mononitration of benzoic acid and of phenol.major product from benzoic acid major product from phenol
Compare the relative ease of nitration of benzene, benzoic acid and phenol. Explain your reasoning; include reference to the structures of the three compounds in your answer. easiest least easy
The azo compound Congo Red is used as an acid-base indicator and can be made by the route shown in Fig. 6.2. In step 3 of this synthesis, compound Y reacts with compound Z. Compound Z is made from compound X. Assume that the -SO groups do not react. step 1 step 2 step 3 Congo Red NaOH(aq)X CY CSNa
Suggest structures for compounds X, Y and Z and draw them in the boxes in Fig. 6.2.
Give the reagents and conditions for step 1 and step 2. step 1 . step 2 . [3] [Total: 16]
State the uses of TMS and D O in NMR spectroscopy. TMS O
The three isomeric ketones with molecular formula C O are:
Complete Table 7.1 to show the number of peaks observed in the proton ( H) NMR spectrum and in the carbon-13 NMR spectrum for each compound listed. Table 7.1 ketone number of peaks observed in the proton ( H) NMR spectrum number of peaks observed in the carbon-13 NMR spectrum 3-methylbutanone
State all the ketones with molecular formula C O that have: a doublet in their proton ( H) NMR spectrum a singlet in their proton ( H) NMR spectrum.
Cortisone, C , is a naturally occurring chemical that contains chiral carbon atoms. cortisone
Deduce the number of chiral carbon atoms in one molecule of cortisone.
Cortisone is reacted with an excess of NaBH State the molecular formula of the organic compound formed.
Cortisone is an optically active molecule. Explain what is meant by optically active. [Total: 8]
Compare the relative acidities of ethanol, ethanoic acid, chloroethanoic acid and phenol. Explain your reasoning. most acidic least acidic
An excess of ethanedioic acid, HOOCCOOH(aq), is reacted with warm acidified KMnO
State the type of reaction undergone by ethanedioic acid. Describe what you would observe. Write an equation for this reaction. Your equation can use [O] or [H] as necessary. type of reaction observations equation
A section of a polyester is shown.O C OCCH polyester OCCH Draw the structures of the two monomers that form this polyester.
Serine can polymerise to form two different types of condensation polymer; a polyester and a polypeptide. serine Draw the structure of the polypeptide showing two repeat units. The peptide linkage should be shown displayed.
Explain why condensation polymers normally biodegrade more readily than addition polymers. [Total: 11]
The structure of cyclohexylamine is shown in Fig. 9.1. cyclohexylamine
Compare the relative basicities of ammonia, cyclohexylamine and phenylamine. Explain your reasoning. most basic least basic
Cyclohexylamine reacts with ethanoyl chloride to form the corresponding amide, L. COCl
Name the mechanism for the reaction shown in Fig. 9.2.
Complete the mechanism of the reaction between cyclohexylamine and CH COCl. R-NH is used to represent cyclohexylamine. Include all relevant lone pairs of electrons, curly arrows, charges and partial charges. CC productsRNH
The reaction between cyclohexylamine and an excess of CH COCl forms compound M. Compound M has the molecular formula C Suggest and draw the structure of M. [1] [Total: 9] Important values, constants and standards Faraday constant F = 9.65 u 10 Avogadro constant L = 6.022 u 10 electronic charge e = ?1.60 u 10?19 molar volume of gas V at room conditions ionic product of water K = 1.00 u 10?14 To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Group The Periodic Table of Elements hydrogen 1.0 He helium 4.0 12131415161718 34567891011123Li lithium 6.9 beryllium 9.0 atomic number atomic symbolKey name relative atomic mass sodium 23.0 magnesium 24.3 potassium 39.1 calcium 40.1 rubidium 85.5 strontiu m 87.6 caesium 132.9 barium 137.3 francium Ra radium boron10.8 13 Al aluminium 27.0 31 Ga gallium 69.7 49 In indium 114.8 thallium 204.4 carbon 12.0 14 Si silicon 28.1 32 Ge germanium 72.6 50 Sntin 118.7 82 Pb lead 207. 2 titanium 47.9 40 Zr zirconium 91.2 72 Hf hafnium178.5 rutherfordium vanadium 50.9 41 Nb niobium 92.9 73 Ta tantalum 180.9 105 Db dubnium chromium 52.0 42 Mo molybdenum 95.9 74 W tungste n 183. 8 106 Sg seaborgium manganese 54.9 43 Tc technetium rhenium 186.2 107 Bh bohrium iron 55.8 44 Ru ruthenium 101.1 76 Os osmium 190.2 108 Hs hassium Co cobalt 58.9 45 Rh rhodium 102. 9 iridium192. 2 109 Mt meitnerium nicke l58.7 46 Pd palladium 106. 4 platinum 195. 1 110 Ds darmstadtium copper 63.5 47 Ag silver 107. 9 79 Au gold 197. 0 111 Rg roentgenium zinc 65.4 48 Cd cadmium 112.4 80 Hg mercury 200. 6 112 Cn copernicium flerovium livermorium nitrogen 14.0 phosphorus 31.0 33 As arsenic 74.9 51 Sb antimony 121.8 bismuth 209.0 oxygen 16.0 sulfur 32.1 34 Se selenium 79.0 52 Te tellurium 127.6 84 Po polonium fluorine 19.0 17 Cl chlorine 35.5 35 Br bromine 79.9 iodine 126.9 Ne neon 20.2 18 Ar argo n39.9 krypto n 83.8 54 Xe xenon131. 3 86 Rn radon nihonium moscovium tennessine oganesson scandium 45.0 yttriu m 88.9 57?71 lanthanoids 89?103 actinoids 57La lanthanum 138.9 89 Ac lanthanoids actinoids actinium Ce cerium 140.1 90 Th thoriu m232.0 praseodymium 140.9 91 Pa protactinium 231.0 neodymium 144.4 uranium 238.0 promethium neptunium samarium 150.4 94 Pu plutonium europium 152.0 95 Am americium gadolinium 157.3 96 Cm curium terbiu m158. 9 97 Bk berkelium dysprosium 162. 5 californium holmium 164. 9 99 Es einsteinium erbium 167. 3 100 Fm fermium Tm thulium168. 9 101 Md mendelevium ytterbiu m 173.1 102 No nobelium lutetium 175.0 lawrencium