Questions and Answers of Cambridge International AS And A Level Chemistry

a. Look back to Figure 29.18. The high resolution NMR spectrum shown is from a sample of ethanol containing traces of water. How would the NMR spectrum differ if D2O had been added to the sample of
a. Name the following compounds:i. CH3CH2CH2CH2CH2NH2ii. (CH3CH2CH2)2NHiii. C2H5NH3+Cl–b. Predict whether diethylamine is a stronger or weaker base than ethylamine. Explain your reasoning.
Draw sketch graphs of reaction rate against concentration of the reactant in bold for each of the following reactions:a. NO(g) + CO(g) + O2(g) → NO2(g) + CO2(g) for which the rate equation is: rate
Use the data from experiments 2 and 3 in Table 22.5 to calculate the rate constant for the following reaction.H2O2(aq) + 2I–(aq) + 2H+(aq) → 2H2O(l) + I2(aq)The rate equation for this reaction
3268 kJ are required to change 1 mole of ethanol into its gaseous atoms.C2H5OH(g) → 2C(g) + 6H(g) + O(g)a. Calculate the entropy change of the surroundings during this process when it is carried
a State the electronic configurations of the following atoms or ions:i. Ti ii. Cr iii. Coiv. Fe3+ v. Ni2+vi. Cu+b. Explain why scandium (which forms only one ion, Sc3+) and zinc (which
Define the following terms:a. Transition elementb. Ligandc. Complex ion.
a. Explain why the 1st ionisation energy of calcium is lower than that of cobalt.b. Explain why the density of calcium is lower than the density of nickel.
Use subshell notation (1s2 2s2 2p6, etc.) to give the electronic configurations of the following:a. An Fe atomb. A Co2+ ionc. A Ti3+ ion.
a. What is the oxidation number of the transition metal in each of the following complexes?i. [Co(NH3)6]3+ii. [Ni(CN)4]2–iii. [Cr(OH)6]3–iv. [Co(en)3]3+v. Cu(OH)2(H2O)4b. EDTA4– ions can act as
a. Write two half-equations for the reactions that take place when Fe2+(aq) is oxidised by dichromate(VI) ions.b. Combine the two half-equations and write the equation for the oxidation of Fe2+(aq)
a. Give the formulae of two iron compounds in which iron has different oxidation states. Give the oxidation states of the iron in each compound.b. Explain why complexes of iron compounds are coloured.
Write balanced ionic equations and describe the observations for the reactions that occur when:a. Sodium hydroxide solution is added to a solution containing [Cu(H2O)6]2+(aq)b. Excess concentrated
a. Cobalt forms a complex with the simplified structure:i. Give the co-ordination number in this complex.ii. Draw the stereoisomer of this complex.iii. Explain why this is a stereoisomer.b. Draw the
The half-cell reactions given below are relevant to the questions that follow.Cl2 + 2e– → 2Cl–
a. Blue cobalt chloride paper gets its blue colour from [CoCl4]2– ions. What is the oxidation number of the cobalt in this complex ion?b. Blue cobalt chloride paper is used to test for water. If
Copper forms complexes with chloride ions and with ammonia.log10 Kstab for aqueous Cu2+ ions with Cl– as a ligand is 2.80.log10 Kstab for aqueous Cu2+ ions with NH3 as a ligand is 4.25.a. A
a. Write expressions for the stability constants for the following reactions:i. [PtCl4]2–(aq) + 2NH3(aq) → PtCl2(NH3)2(aq) + 2Cl–(aq)ii. [Cr(H2O)6]3+(aq) + 2Cl–(aq) → [Cr(H2O)4Cl2]+(aq) +
a. What do we mean by degenerate atomic orbitals?b Explain why an octahedral complex of a transition element is coloured.c. Draw the non-degenerate 3d orbitals in a Ni2+ ion on a diagram similar to
a. A solution of Sc3+ ions is colourless. Suggest a reason for this.b. A solution of Zn2+ ions is colourless. Suggest a reason for this.
a. How many electrons are involved in the π bonding system in a benzene molecule?b. From which type of atomic orbital do the electrons in part a come from?c. What do we mean by the term
a. What is the empirical formula of benzene?b. What is the molecular formula of benzene?c. i. Draw the full displayed formula of the Kekulé structure of benzene, showing all atoms and using double
a. Draw the displayed or skeletal formula of:i. 1,3,5-tribromobenzeneii. 1,3-dichloro-5-nitrobenzene.b. Name the molecules below:i.ii. OH CH3
Benzene reacts with bromine.a. Write a balanced chemical equation for this reaction.b. Name the catalyst used.c. What visual observations could be made during the reaction?d. Benzene will also react
a. Write the equation for the reaction of chlorine with benzene in the presence of an iron(III) chloride catalyst.b. What do we call this type of mechanism for the reaction in part a?c. Draw the
Phenol is an aryl compound.a. i. What is the molecular formula of phenol?ii. What is the empirical formula of phenol?b. Molten phenol reacts with sodium metal. Give one observation and write a
a. Copy and complete the two equations below, which can be used to show the nitration of methylbenzene:i. C6H5CH3 + NO2+ → — + — ii. iii. Name the possible
Benzene can be nitrated to give nitrobenzene.a. Name the mechanism for this reaction.b. The species attacking benzene in the reaction is NO2+. How is this generated in the reaction mixture?(Name the
a. Copy and complete the two equations below, which can be used to show the alkylation and acylation of benzene, to produce the monosubstituted products.i. C6H6 + CH3CH2CH2Cl → — + — ii.
a. Describe the bonding in benzene. Include a description of the model used for the arrangement of electrons in the molecule.b. Cyclohexene decolorises bromine water; benzene has no effect on bromine
Hexylbenzene is refluxed with alkaline potassium manganate(VII) and then acidified with dilute sulfuric acid. The same experiment is carried out using hexane and the oxidising agent. Compare what
a. Place the following molecules in order of their acidity, starting with the most acidic:CH3COOH C6H5OH
a. Place these molecules in order of ease of nitration, with the most reactive first:C6H6 C6H5CH3
a. Place the following acids in order of strength, starting with the strongest acid first.CH3CH2COOH CH3CCl2COOH CH3CHClCOOHb. Explain why
Acyl chlorides and carboxylic acids can both be used to prepare esters.a. i. Give the reagents and conditions required to make ethyl ethanoate directly from a carboxylic acid.ii. Write an equation to
a. Why is methanoic acid never prepared by refluxing methanol with acidified potassium dichromate(VI) solution?b. Look back at the two half-equations for the oxidation of methanoic acid. Write two
a. Draw the displayed formula of butanoyl chloride.b. i. Give the name and formula of a reagent that can be used to prepare butanoyl chloride from butanoic acid.ii. Write a balanced equation for the
Write a balanced equation, using structural formulae for the organic compounds, and state any conditions necessary, to show the formation of:a. Propanoyl chloride from a suitable carboxylic acid and
In its reaction with a nucleophile, explain why an acyl chloride reacts faster than an alcohol.
a. Name the products of the hydrolysis of propanoyl chloride.b. i. Place the following compounds in order of ease of hydrolysis, starting with the most reactive first.C6H5Cl
a. Using an acyl chloride as a starting compound in each case, name the reactants you would use to make:i. Ethyl ethanoateii. Methyl butanoateiii. Phenyl benzoate.b. Complete the following
Ethylamine and phenylamine are two organic nitrogen compounds. Both compounds are basic.a. Draw the displayed formula of each compound, including lone pairs.b. Write a balanced symbol equation for
a. i. Give the reagents and conditions needed to make butylamine from butanenitrile.ii. Name the bromoalkane that can be used to make the butanenitrile in part a i.iii. Name two types of organic
Phenylamine can be made using nitrobenzene as starting material.a. Name this type of reaction.b. What reagents are used to bring about this change?c. Write a balanced symbol equation for this
The R groups in the 2-amino-carboxylic acids alanine and valine are —CH3 and (CH3)2HC— , respectively.a. Draw the structures of both these amino acids.b. Give an equation to show the formation of
a. i. Which would be more readily attacked by an electrophile – benzene or phenylamine? Explain your answer.ii. Write a general equation to show the equation for the reaction of phenylamine with
The formulae of two amino acids, glycine (Gly) and alanine (Ala), are given here:glycine is H2nCH2CooH alanine is H2nCH(CH3)CooH.a. i. Give the systematic
Phenylamine reacts with nitrous acid (nitric (III) acid) to form a diazonium salt.a. Which two reagents would you use to prepare the nitrous acid?b. What are the essential conditions for the
a. i. What is the general structural formula of a 2-amino-carboxylic acid?ii. Why are all amino acids solids at 20°C?b. i. Draw the displayed formula of the 2-aminocarboxylic acid called serine, in
a. Write an equation to show the formation of the following compounds using an acid chloride:i. Propanamideii. N-ethylpropanamide.b. Write an equation to show the hydrolysis of:i. butanamide by
The diazonium salt formed in question 3 reacts with phenol to form a useful substance, X.a. What are the essential conditions for the reaction?b. Give the displayed formula of X.c. Write a balanced
A mixture of three amino aids is separated by gel electrophoresis. The three amino acids are glycine, valine and phenylalanine (Figure 27.14).a. The electrophoresis is carried out in a buffer
The structure of a certain tripeptide is shown here:a. i. Draw the displayed formulae of the three amino acids that make up the tripeptide.ii. Which of these amino acids has two chiral carbon
a. Which of these monomers form addition polymers and which form condensation polymers?i. NH2CH(CH3)COOHii. H2C=CHC6H5iii. H2C=CHCOOHiv. NH2CH2COOHv. CH3CH(OH)COOHb. Explain the basis of your
Both glycine and alanine are amphoteric.a. Explain the term amphoteric.b. Explain the structural features of both glycine and alanine that enable them to be amphoteric.c. i. Amino acids form
Different types of nylon are identified by the number of carbon atoms in each of its monomers, with the diamine quoted first, followed by the dicarboxylic acid.a. Draw the skeletal formula of each
a. Explain the term condensation polymer.b. Kevlar is a condensation polymer that is used for making bullet-proof vests. Here are two monomers that could be used for making Kevlar:i. Explain the term
a. Polyesters are condensation polymers. Give the structures of two monomers that could be used to give a polyester.b. Give the structure of the polyester formed from these two monomers.
a. Name and give the formulae of the two functional groups present in all amino acids.b. Name an example of an amino acid with a nonpolar side-chain.c. Draw a diagram of two molecules of serine to
a. Glycine is an amino acid with the formula H2NCH2COOH.i. Give the systematic name for glycine.ii. Give the structure of the polymer that could be formed from glycine, showing at least two repeat
a. A polypeptide is said to have direction. How are the two ends of the chain described?b. What type of chemical bonding is responsible for maintaining the primary structure of a protein?c. What is
Sections of some polymers are shown below. For each polymer:i. Identify the repeat unit.ii. Give the structures of the monomers used to make the polymer.a.b.c.d.e. || || C-0 0-C O=C
Give the structures of the polymers formed from the monomers given below, showing at least two repeat units. For each polymer identify the following:i. The repeat unitii. The type of linkage
The diagram here represents the basic chemical unit from base which DNA is formed.a. State the name of: i. The whole unit ii. Xiii. Yb. Name the four nitrogen-containing bases present in
a. Representing the nitrogen-containing bases by 'B' sugars by 'S' and phosphate groups by 'P', show how these are linked in a short length of double-stranded DNA. Use full lines (——) to show
a. Explain the term biodegradable.b. Explain how the production of biodegradable polymers has lessened the impact of polymers on the environment.c. Poly(L-lactic acid) is a biodegradable polymer.
a. An analysis of the bases in a sample of doublestranded DNA gave the partial result: adenine 23 mol % and guanine 27 mol %. What would you expect the rest of the analysis to show? Explain your
Ribonuclease is an enzyme. Its secondary structure contains both α-helices and β-pleated sheets.a. i. Describe the structure of a typical α-helix.ii. Describe the structure of a typical β-pleated
a. Draw the repeat unit of the polyester, PLA.b. Draw the repeat unit of Terylene®.
The structure of DNA is stabilised by hydrogen bonding.a. Give the full name of DNA.b. Write the names of the bases A, C, G and T.c. Explain, in terms of intermolecular bonding, how the structure of
a. The word ‘resilient’ means to return to the original form or position after being bent, compressed or stretched. Explain why the process of vulcanising makes rubber ‘more resilient’.b.
Three levels of protein structure are primary, secondary and tertiary.a. Describe the primary structure of a typical protein containing one polypeptide chain. Name the type of chemical bonding
a. How does a non-solvent-based adhesive, such as an SMP, set to become a solid?b. What type of monomers react together to form an epoxy resin?c. i. Draw the displayed formula of the monomer used in
a. What type of polymerisation reaction formed the polymer shown below?b. Draw the displayed formula of the single monomer used to make the polymer shown in part a. H H H O H H H |
a. Identify the fragments that would cause peaks in the mass spectrum of HOCH2COCH3 with the following m/e values:i. m/e = 15ii. m/e = 17iii. m/e = 31iv. m/e = 43v. m/e = 57vi. m/e = 59b. At what
Look at this paper chromatogram:a. The solvent used was ethanol. Which sample of ink, A, B or C, has the greatest relative solubility in ethanol?b. Work out the Rf value of the ink whose partition
The gas–liquid chromatogram for a mixture of organic compounds is shown below.a. Give the correct labels for a, B and C.b. What percentage of the mixture is pentan-1-ol?c. Give an explanation for
Compound E has the composition 69.8% carbon, 11.6% hydrogen and 18.6% oxygen. Its mass and 1H NMR spectra are shown below.a. Calculate the empirical formula of E.b. From the mass spectrum, find the
a. Look at the series of lines clustered at about 125 ppm in Figure 29.22.i. One line is separated slightly from the main cluster – explain which carbon atom in ethylbenzene is most likely to have
a. TLC can separate mixtures of components. What do we call the mechanism of separation usually at work in TLC?b. A mixture of propanone and hexane was separated on a TLC chromatogram using alumina
Paper chromatography was used to separate a mixture of amino acids. The mixture was run in two dimensions using two different solvents. The chromatogram obtained is shown below.a. Explain briefly how
a. For GLC separations explain:i. How retention time is measuredii. How the areas under the component peaks are used.b. What can you use as an approximate measure of the proportion of a component in
Compound B has the composition 62.1% carbon, 10.3% hydrogen and 27.6% oxygen. Its mass and 1H NMR spectra are shown below.a.b.a. Calculate the empirical formula of B.b. From the mass spectrum, find
a. Explain why tetramethylsilane (TMS) is used as a standard in NMR spectroscopy.b. In NMR we use solvents such as tetrachloromethane to prepare samples for the machine (Figure 29.16).i. What is the
Predict the number of peaks and the relative areas under each peak, where appropriate, on the low resolution proton NMR spectrum of:a. Methanol, CH3OHb. Benzene, C6H6c. Chloroethane, C2H5Cld.
Arene C has the composition 90.6% carbon and 9.4% hydrogen. Its mass and 1H NMR spectra are shown below.a.b.a. Calculate the empirical formula of C.b. From the mass spectrum, find the molecular mass
A pathologist was given a sample of a white tablet found at the scene of a suicide. In order to complete her report the pathologist received an NMR spectrum of the sample (Figure 29.20a) and
Compound D has the composition 77.8% carbon, 7.41% hydrogen and 14.8% oxygen. It mass and 1H NMR spectra are shown below.a.b.a. Calculate the empirical formula of D.b. From the mass spectrum, find
Look at Figure 29.25, which shows the mass spectrum of ethanol, C2H5OH. A structural isomer of ethanol is methoxymethane, an ether with the formula CH3OCH3.a. Predict the mass-to-charge ratio of a
A hydrocarbon has a molecular ion peak at a mass-to charge ratio of 84 (relative abundance of 62.0%) and an [M + 1] peak with a relative abundance of 4.1%.a. How many carbon atoms are in the
a. List the ions responsible for the M, [M + 2] and [M + 4] peaks in a mass spectrum of dibromomethane.b. What would be the mass-to-charge ratio and relative abundances of the major peaks with the
Look at Figure 29.27.a. What is the retention time of the compound shown?b. What is the approximate relative molecular mass of the compound shown?c. How would the compound be identified? 100 200 80
Look at Figure 29.28.a. Calculate the relative molecular mass of leucine enkephalin (C28H37N5O7) using relative atomic masses. (Ar values C = 12.0, H = 1.0, N = 14.0, O = 16.0)b. i. How is the
a. Which method was used to determine the structure of HIV protease in 1988?b. Which method could be used to show the shape of the enzyme in solution?c. What type of natural polymer is an enzyme such
A sample of lactic acid (CH3CH(OH)COOH) was extracted from a natural source and found to be optically active. It was then subjected to two reactions, as shown below.Sample 1 was optically active but
In an experiment to determine the formula of an oxide of copper, the copper oxide was reduced by hydrogen gas. The hydrogen was passed over the oxide of copper in a boiling tube with a hole near its
a. Why are pure enantiomers rather than racemic mixtures the better option for use as pharmaceutical drugs from the point of view of:i. A patientii. A pharmaceutical company?b. Why are modern
Explain how 2-aminopropanoic acid can be prepared from lactic acid in two steps. You should give the reagents and conditions necessary plus balanced symbol equations for the reactions taking place.
a. In the experiment described in Question 1, a student weighed a mass of 11.35 g of the oxide of copper on a balance reading to the nearest 0.05 g. What was the percentage error in this
a. Name the functional groups in the molecules of:i. Aspirinii. Paracetamol.b. i. Both the molecules in part a are broken down when refluxed with dilute hydrochloric acid. Write an equation each for

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