CAIE
Chemistry
(9701)
Questions & Answers
Manganese, Mn, and its compounds are widely used in many chemical reactions.
Mn is usually found as a single isotope, manganese-55.
Determine the number of protons, neutrons and electrons in an atom of manganese-55. number of protons neutrons electrons
Define isotopes.
A sample of manganese from the Moon is found to contain manganese-53 in addition to manganese-55. State the two pieces of information needed to determine the relative atom ic mass, A , of manganese in this sample. 1 2
The shorthand electronic configuration of manganese is [Ar] 3d
Complete the full electronic configuration of manganese.
Deduce the total number of unpaired electrons in an atom of manganese.
Manganese(IV) oxide reacts with methanal, CH O, in acidic conditions to produce carbon dioxide. The movement of electrons to or from relevant species is shown in the following half-equations. half-equation 1 CH O + H O CO + 4H + 4e half-equation 2 MnO + 4H + 2e + 2H
Identify the species that is reduced in half-equation 2. Explain your answer.
The oxidation state of carbon in methanal is 0. Calculate the oxidation state of carbon in carbon dioxide.
Construct the ionic equation for the reaction of manganese( IV) oxide with methanal in acidic conditions. [Total: 10] * 0000800000003 *
The Period 3 elements show trends in physical and chemical properties across the period.
(i) Explain why the elements Na to Al are good electrical conductors.
Explain why the elements P, S and Cl do not conduct electricity .
Fig. 2.1 shows the variation in melting point of the Period 3 elements Si to Cl. 1800 1600 1400 1200 1000 melting point / K Si P S Cl The Period 3 elements Si to Cl are all non-metals. Explain why there is a large dif ference between the melting point of Si and the melting points of P, S and Cl.
Table 2.1 gives some information about some Period 3 chlorides. Row B refers to the pH of the solution that forms when the Period 3 chloride is added to water. Table 2.1 formula of Period 3 chlorideNaCl MgCl Al Cl SiClPCl oxidation number of element bonded to Cl B pH of solution 6.5 C bonding ionic D structure giant Complete T able 2.1. Y ou may use the following abbreviations. I = ionic, C = covalent, M = metallic G = giant, S = simple
(i) Write an equation for the formation of Al Cl from its elements.
Write an equation for the formation of H from PCl
reacts with Cl
in a reversible reaction to form SCl
Under certain conditions, a dynamic equilibrium is established.
State what is meant by dynamic equilibrium.
Identify the condition necessary to establish dynamic equilibrium.
is yellow and SCl
is red.
State what is observed when the following changes are made to an equilibrium mixture of S
and SCl
Explain your answers. observation explanation observation explanation
Aqueous MgCl reacts with aqueous Na to form a white precipitate. Upon heating, the white precipitate undergoes thermal decomposition.
Construct an equation to show the reaction of aqueous MgCl with aqueous Na Use state symbols in your equation.
Identify the products of the thermal decomposition of the white precipitate.
State the trend in thermal stability of the Group 2 carbonates down the group. [Total: 20] * 0000800000006 * BLANK PAGE * 0000800000007 *
The alkanes are a homologous series of organic molecules. Alkanes are generally unreactive and are commonly used as fuels.
Define homologous series.
Give two reasons to explain the general unreactivity of alkanes. 1 2
Alkanes with low relative molecular mass, M , are more useful than those found in heavier crude oil fractions. Name the process that is used to obtain alkanes with low M from heavier crude oil fractions.
Hexane, C , has four structural isomers. Fig. 3.1 shows hexane and two of its structural isomers. DCBAhexane
Complete Fig. 3.1 by drawing structures for C and D, the other two structural isomers of hexane.
A, B and hexane have dif ferent boiling points. Arrange A, B and hexane in order of increasing boiling point. Explain your answer. lowest < < highest [3] * 0000800000008 *
Hexane can be converted into compounds E and F at high temperature and pressure. Fig. 3.2 shows the reaction scheme involving hexane, E and F. reaction 3 reaction 2 = +215 kJ mol reaction 1E F
Identify a suitable reagent for reaction 3.
Use the data in Fig. 3.2 and in Table 3.1 to calculate the enthalpy change of reaction 2, Table 3.1 compound enthalpy change of / kJ mol +48 = kJ mol
Write an equation for the complete combustion of hexane. [Total: 14] * 0000800000009 *
Fig. 4.1 shows how propane, C , can be converted to propanoic acid, CH COOH. Cl CH OH CH COOH reaction 1 reaction 2 reaction 3
Reaction 1 in Fig. 4.1 takes place in the presence of sunlight. + Cl Cl + HCl The reaction takes place via initiation, propagation and termination steps.
Name the mechanism shown by reaction 1.
Complete the mechanism for reaction 1. Construct equations to describe the steps of the mechanism. initiation Cl propagation 1 propagation 2 termination CH
Reaction 1 is initiated by the bond fission of Cl State the type of bond fission shown in the initiation step.
Compound Q is a by-product of reaction 1. HCCCHHHHCl Name Q.
The molecular formula of Q is C Identify the types of structural isomerism and stereoisomerism that a molecule with molecular formula C can show. type of structural isomerism type of stereoisomerism
State the reagent and solvent required for reaction 2.
Reaction 3 takes place when CH OH is heated under reflux with acidified potassium dichromate(VI) solution.
State the colour change that takes place in the reaction mixture.
Construct an equation to represent reaction 3. Use [O] to represent an atom of oxygen from the oxidising agent.
CH COOH reacts with an unsaturated alcohol R to form unsaturated ester S.
State the type of reaction that forms S.
The infrared spectrum of S is shown in Fig. 4.2. 4000 3000 2000 1500 wavenumber / cm 1000 500 transmittance / % Three absorptions in the infrared spectrum in Fig. 4.2 confirm that S is an ester and is unsaturated. have identified in Fig. 4.2. Table 4.1 absorption 1 2 3 bond responsible [3] * 0000800000012 * Table 4.2 bondfunctional groups containing the bond characteristic infrared absorption range (in wavenumbers) / cm C-Ohydroxy, ester 1040-1300 C=Caromatic compound, alkene 1500-1680C=O amide carbonyl, carboxyl ester CNnitrile 2200-2250 C-Halkane 2850-2950 N-Hamine, amide 3300-3500O-H carboxyl hydroxy
The mass spectrum of S shows the following peaks. Table 4.3 peak relative abundance 4.7 [M+1] 0.31 Use Table 4.3 to calculate the number of carbon atoms in S. number of carbon atoms in S = [1] [Total: 16] * 0000800000013 * BLANK PAGE * 0000800000014 * Important values, constants and standards molar gas constant R = 8.31 J Kmol Faraday constant F = 9.65 × 10 C mol Avogadro constant L = 6.02 × 10mol electronic charge e = -1.60 × 10-19 molar volume of gas V = 22.4 dmmol at s.t.p. (101 kPa and 273 K) = 24.0 dmmol at room conditions ionic product of water K = 1.00 × 10-14mol (at 298 K (25 °C)) (4.18 J g ) * 0000800000015 * 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 Ta ble of Elements hydrogen 1.0 helium 4.0 12 13 14 15 16 17 18 3456789 10 11 12 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 strontium 87.6 caesium 132.9 barium 137.3 francium radium boron 10.8 aluminium 27.0 gallium 69.7 indium 114.8 thallium 204.4 carbon 12.0 silicon 28.1 germanium 72.6tin 118.7 lead 207.2 titanium 47.9 zirconium 91.2 hafnium 178.5 rutherfordium vanadium 50.9 niobium 92.9 tantalum 180.9 dubnium chromium 52.0 molybdenum 95.9 tungsten 183.8 seaborgium manganese 54.9 technetium rhenium 186.2 bohrium iron 55.8 ruthenium 101.1 osmium 190.2 hassium cobalt 58.9 rhodium 102.9 iridium 192.2 meitnerium nickel 58.7 palladium 106.4 platinum 195.1 darmstadtium copper 63.5 silver 107.9 gold 197.0 roentgenium zinc 65.4 cadmium 112.4 mercury 200.6 copernicium flerovium livermorium nitrogen 14.0 phosphorus 31.0 arsenic 74.9 antimony 121.8 bismuth 209.0 oxygen 16.0 sulfur 32.1 selenium 79.0 tellurium 127.6 polonium fluorine 19.0 chlorine 35.5 bromine 79.9 iodine 126.9 neon 20.2 argon 39.9 krypton 83.8 xenon 131.3 radon nihonium moscovium tennessine oganesson scandium 45.0 yttrium 88.9 57-71 lanthanoids 89-103 actinoids lanthanum 138.9 lanthanoids actinoids actinium cerium 140.1 thorium 232.0 praseodymium 140.9 protactinium 231.0 neodymium 144.2 uranium 238.0 promethium neptunium samarium 150.4 plutonium europium 152.0 americium gadolinium 157.3 curium terbium 158.9 berkelium dysprosium 162.5 californium holmium 164.9 einsteinium erbium 167.3 fermium thulium 168.9 mendelevium ytterbium 173.1 nobelium lutetium 175.0 lawrencium - * 0000800000016 *