Chemistry 2022 · May/June · Paper 22

Radium, Ra, is an element found in Group 2 of the Periodic Table. It is a crystalline solid at room temperature and conducts electricity.

based on the properties described.

Solid Ra and Ca show similar reactions with H O, but the reactions occur at different rates. Separate samples, each containing a single piece of solid Ra or Ca, are added to equal volumes of cold water. Each sample contains equal numbers of moles of solid and the H O is in excess.

Construct an equation for the reaction of Ra with H

Identify which element, Ra or Ca, reacts with H O at a faster rate. Suggest how the observations of each reaction would differ.

Suggest why these reactions occur at different rates.

One of the solutions is cloudy when the reaction has finished. At the end of each reaction, universal indicator is added to each reaction mixture. Suggest pH values of the solutions made in both reactions. Explain your answer.

A sample of aqueous calcium halide, CaX

, contains either chloride, bromide or iodide ions. Complete Table 2.1 to describe a two-step process that could be used to identify the halide ion present. Table 2.1 step method observation observation with CaBr observation with CaI step 1 step 2 [3] [Total: 11] equation 1 2HI(g)

Explain what is meant by dynamic equilibrium.

Describe one difference in the initial appearance of the reaction mixture compared to the mixture at equilibrium.

Write an expression for K for the reaction described in equation 1. [1] Calculate the amount of HI

present in the mixture at equilibrium. Show your working. amount of HI

= mol

Use equation 1 and the bond energy values in Table 3.1 to calculate the change in enthalpy, Table 3.1 H-H 436 I-I 151 H-I 299

Describe the effect of increasing pressure on the value of K for the decomposition of HI

is not prepared by adding NaI

to concentrated H because the HI

produced also reacts with concentrated H

Identify the type of reaction that occurs when NaI

reacts with concentrated H form HI

Write an equation for the reaction of HI

and concentrated H

Explain why HI

reacts with concentrated H whereas HCl does not. [Total: 12]

Bromine reacts with butane in the presence of ultraviolet light to form bromobutane. Two structural isomers with the molecular formula C Br are produced during this reaction.

Draw the two structural isomers and state the systematic name of each isomer. structural isomer 1 name structural isomer 2 name

Identify the type of structural isomerism shown in (a)(i).

Halothane is an anaesthetic. halothane

Identify the chiral centre in halothane and mark it with an asterisk (*). [1] When halothane reacts in ultraviolet light, homolytic fission occurs and the C-Br bond is broken.

Construct an equation to show the homolytic fission of halothane, CF CHBrCl.

Complete Fig. 4.2 to show the arrangement of electrons in a bromine atom using the electrons in boxes notation. [Ar] 4p4s

X is an addition polymer.

Draw the monomer of X.

Suggest one reason why the disposal of items made from X is difficult. [Total: 8]

Fig. 5.1 shows three reactions of 2-bromopropane, CH CH(Br)CH CH(Br)CH CH(NH)CH CH(OH)CH C=CHCH reaction 1 reaction 3 reaction 2

Complete Table 5.1 for each reaction, by: Table 5.1 reaction reagent and conditions type of reaction

A sample of 2-iodopropane, CH CH(I)CH , reacts under the same conditions as reaction 1 to produce CH CH(OH)CH Explain why 2-iodopropane reacts at a faster rate than 2-bromopropane.

Fig. 5.2 shows how butan-1-ol can be made from 1-bromopropane in three steps. step 1 step 2 step 3 N HO

In step 1, 1-bromopropane reacts with CN to form butanenitrile. Complete Fig. 5.3 to show the mechanism for step 1. Include charges, dipoles, lone pairs of electrons and curly arrows as appropriate. Br HC [2] Construct an equation for the reaction in step 2.

Step 3 is a reduction reaction. Construct an equation for the reduction reaction in step 3. Use [H] to represent one atom of hydrogen from the reducing agent.

State the identity of a suitable reducing agent in step 3. [Total: 13]

Z is a molecule which contains the elements carbon, hydrogen and oxygen only. Z contains only alkene and carboxyl functional groups.

Complete Table 6.1 by describing the observations that occur when two different reagents are added to separate samples of Z(aq). Table 6.1 reagent added to Z(aq) observation

Table 6.2 shows the percentage by mass of each element present in Z. Table 6.2 carbon 41.38 hydrogen 3.45 oxygen 55.17 Using the data in Table 6.2, demonstrate that the empirical formula of Z is CHO. Show your working.

Fig. 6.1 shows the mass spectrum of Z. 10 20 30 40 50 60 70 80 90100 120110 relative abundance/ e

Deduce the molecular formula of Z. Explain your answer by referring to the molecular ion peak in Fig. 6.1 and the empirical formula of Z.

Use Fig. 6.1 to suggest the formulae of the fragments with m / e peaks at 45 and at 71. / e 45 / e 71

Suggest the structure of Z using relevant information from Table 6.1,

. [1] [Total: 7] 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 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 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.