17.1. Aldehydes and ketones
A subsection of Chemistry, 9701, through 17. Carbonyl compounds
Listing 10 of 304 questions
W is CH3COCH2CH3. The reaction between W and alkaline aqueous iodine produces a yellow precipitate. Give the name of the compound formed as a yellow precipitate in this reaction. Give the name of W. There are two structural isomers of W that are also carbonyl compounds. Draw the structures of these two isomers of W.  Two reactions of W are shown. CH3COCH2CH3 CH3CH(OH)CH2CH3 H3C CH2CH3 C OH CN W X reaction 2 reaction 1 Identify the type of reaction occurring in reaction1. Identify the reagent for reaction1. Reaction2 is carried out by adding a mixture of HCN and NaCN to W. The product, X, is formed as a mixture of two isomers. Complete the mechanism for this reaction. Include the structure of the intermediate formed and all necessary charges, dipoles, lone pairs and curly arrows. H3C CH2 CH3 O C W X CN– H3C CH2CH3 C OH CN  State the name of the type of isomerism shown by X. Explain fully why X shows this type of isomerism. Question 4 continues on page 10. If X is treated with ammonia and the product hydrolysed, a compound, Y, is obtained that contains 51.3% C, 9.40% H, 12.0% N and 27.3% O by mass. Show that the empirical formula of Y is C5H11NO2.  The empirical formula of Y is C5H11NO2 and the Mr of Y is 117. Deduce the molecular formula of Y. You must explain your reasoning. molecular formula =  
9701_s18_qp_22
THEORY
2018
Paper 2, Variant 2
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CompoundV is a liquid. V contains 77.2% carbon, 11.4% hydrogen and 11.4% oxygen by mass. V has a relative molecular mass of 280. Calculate the molecular formula of V. Show your working.  molecular formula of V = V contains two types of functional group: a carboxylic acid and an alkene. Describe a chemical test and observation which confirms the presence of a carboxyl functional group. A 3.196 g sample of Br2 reacts completely with 2.800 g of V. Calculate how many alkene functional groups are present in one molecule of V. Show your working.  number of alkene functional groups in V = W, X and Y have the same molecular formula, C5H10O. W, X and Y are added separately to different reagents. Observations for these reactions are described in Table4.1. Table 4.1 + 2,4-dinitrophenylhydrazine + alkaline I2+ Fehling’s reagent and warm W orange precipitate seen no change orange-red precipitate seen X orange precipitate seen yellow precipitate seen no change Y orange precipitate seen W, X and Y each contain a common functional group. Name the functional group that is present in all three compounds. State the formula of the yellow precipitate produced when X is added to alkaline I2. W could be one of four structural isomers. ● Draw the skeletal formulae for two possible structural isomers of W. ● Describe the type of structural isomerism shown. isomer 1 isomer 2 type of structural isomerism  Fig.5.1 shows the mass spectrum of ketone Z, C5H10O. % abundance m/e value Use the information in Fig.5.1 to suggest the formulae of the fragments with m/e peaks at 29 and 57. Deduce the identity of Z. m/e = 29 m/e = 57 identity of Z  
9701_s22_qp_21
THEORY
2022
Paper 2, Variant 1
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State two typical chemical properties of a transition element. Aqueous solutions of cobalt(salts contain the complex ion [Co(H2O)6]2+. Define complex ion. Samples of [Co(H2O)6]2+ are reacted separately with an excess of aqueous ammonia, with an excess of concentrated HCl and with an excess of aqueous sodium hydroxide, as shown in . excess NH3excess NaOHexcess concentrated HCl [Co(H2O)6]2+A C B Complete Table 2.1 about the reactions shown by [Co(H2O)6]2+. Table 2.1 reagent added to [Co(H2O)6]2+formula of cobalt species formed colour and state of cobalt species formed type of reaction an excess of NH3A = an excess of concentrated HCl B = an excess of NaOHC = The ethanedioate ion, C2O4 2–, can act as a bidentate ligand. Explain what is meant by a bidentate ligand. The complex [Co(H2O)2(C2O4)BrCl ]− exists as stereoisomers. Complete the three-dimensional diagrams in to show four stereoisomers of [Co(H2O)2(C2O4)BrCl ]−. The C2O4 2– ligand is represented using O O . O Co O O Co O O Co O O Co O State the oxidation state of cobalt in this complex and a type of stereoisomerism shown. oxidation state of cobalt type of stereoisomerism
9701_s23_qp_42
THEORY
2023
Paper 4, Variant 2
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