14. Hydrocarbons
A section of Chemistry, 9701
Listing 10 of 313 questions
In each section of this question choose the answer or answers from the options listed. Six particles are listed. H• H+ Cl • Cl – •CH3 +CH3 Identify two particles produced during the reaction of methane and chlorine in the presence of UVlight. Identify the two particles produced by the heterolytic fission of a bond in chloromethane. Seven reaction types are listed. addition substitution oxidation elimination hydrolysis condensation reduction Name the type of reaction involved when Tollens’ reagent is used to identify an aldehyde. Name the type of reaction involved in the test for a carbonyl group using 2,4-DNPH. Name the type of reaction involved in the reaction of a ketone with NaBH4. Name the type of reaction involved in the reaction of an aldehyde with HCN.
9701_w16_qp_22
THEORY
2016
Paper 2, Variant 2
View
Some reactions are shown, based on methylpropan-2-ol, (CH3)3COH. (CH3)3COH (CH3)3CBr and (CH3)2CHCH2Br (CH3)2C=CH2 (CH3)3CBr reaction 1 reaction 2 reaction 3 reaction 4 For each of the reactions state the reagent, the particular conditions required, if any, and the type of reaction. For the type of reaction choose from the list. Each type may be used once, more than once or not at all. Each reaction may be described by one or more than one type. hydrolysis dehydration substitution oxidation addition condensation reaction reagentand conditions typeof reaction Draw a diagram to show the SN1 mechanism of reaction 2. Include all necessary charges, dipoles, lone pairs and curly arrows. 1-bromobutane is a structural isomer of the product of reaction 1. Define the term structural isomer and name the three different types of structural isomerism. definition types of structural isomerism 1-bromobutane is treated with the same reagents as in reaction2. Butan-1-ol is formed. Identify the mechanism of this reaction. Explain why this reaction proceeds via a different mechanism from that of reaction2. mechanism explanation  The product of reaction 3, methylpropene, does not show stereoisomerism. Give two reasons why methylpropene does not show stereoisomerism. Methylpropene can be polymerised to form a poly. State the type of polymerisation and draw the repeat unit of the polymer formed from methylpropene. type of polymerisation repeat unit State the difficulty associated with the disposal of poly. Name the two products of reaction 4. name of (CH3)3CBr name of (CH3)2CHCH2Br
9701_w17_qp_22
THEORY
2017
Paper 2, Variant 2
View
Define the term transition metal complex. Platinum can form the compound [Pt(NH3)4Cl 2][PtCl 4]. State the co-ordination numbers and the oxidation numbers of the platinum in the two ions of this compound. co-ordination number oxidation number [Pt(NH3)4Cl 2]2+ [PtCl 4]2– Draw three-dimensional diagrams to show the structures of the two isomers of [Pt(NH3)4Cl 2]2+. Solutions of the compounds [Pt(NH3)4Cl 2]Br2 and [Pt(NH3)4Br2]Cl 2 can be distinguished from each other by a simple chemical test. Assume that any species bonded to the platinum ion does not react in this test. Complete the table with a test that could be used to positively identify each compound. Give details of expected observations with each compound. test observation with [Pt(NH3)4Cl 2]Br2 observation with [Pt(NH3)4Br2]Cl 2 In this question you should consider geometrical and optical isomerism. What type of isomerism is shown by the following complexes? You should answer geometrical, optical, both or neither. octahedral [Co(NH2CH2CH2NH2)2Cl 2]+ square planar [Ni(CN)2Cl 2]2– tetrahedral [CuBr2Cl 2]2–  Many enzymes contain transition metal complexes. Describe, with the aid of a suitably labelled diagram, how an enzyme catalyses the breakdown of a substrate molecule.
9701_w17_qp_42
THEORY
2017
Paper 4, Variant 2
View
Calcium carbide, CaC2, reacts readily with water, forming ethyne, C2H2, and a sparingly soluble white ionic compound. Write an equation for the reaction of CaC2 with water. Draw a ‘dot-and-cross’ diagram for the carbide ion, C2 2–. Show outer electrons only. Ethyne is the simplest member of the alkyne homologous series. C ethyne H C H Propyne, C3H4, and butyne, C4H6, are the next two members of the series. Deduce the general formula for the alkynes. Ethyne can be polymerised into poly, which is a conducting polymer. C C H H polyn Suggest why this polymer conducts electricity. State the empirical formula of poly. By reference to a physical or chemical property, suggest one advantage of a conducting polymer when compared with metals. Alkynes can react with carbonyl compounds under basic conditions as shown in reaction1. C R C C small amount of base R' R'' O H C R C C reaction 1 R' OH R'' The first step of the mechanism of reaction1 involves the alkyne anion reacting with the carbonyl compound. Complete the first step of the mechanism and draw the intermediate for this reaction. Include all relevant dipoles, charges and curly arrows. C R C– C R' R'' O C R C intermediate C R' OH R'' Suggest the name of the mechanism in reaction 1. An alkyne, Q, and a carbonyl compound, R, react together to form compound P as shown. C CH2 C C C C2H5C C2H5C CH3 CH3 OH OH P 2Q + R Use reaction 1 to suggest the structures of Q and R. Q R A series of twelve separate experiments is carried out as shown in the table. Complete the table by writing in each box a tick () if a reaction occurs, or a cross ( ) if no reaction occurs. CH3CHO HCO2H CH3COCH3 HO2CCO2H hot, acidified MnO4 –alkaline I2warm Tollens’ reagent 
9701_w17_qp_42
THEORY
2017
Paper 4, Variant 2
View
The diagram shows a reaction sequence starting from ethanal. C P ethanal H3C H3C CO2H CO2H OH C C C R Q H H H O C S H3C O H CO2H HCN and NaCN reaction 1 H2SO4reaction 2 reaction 3 reaction 4 H Draw the displayed formula of P.  Name the type of chemical reaction that occurs in reaction3. Write an equation to represent reaction4. Use to represent the oxidising agent. State the reagents and conditions for reaction4. CompoundQ is formed as a mixture of two optical isomers. Explain what is meant by the term optical isomers. Draw the two optical isomers of Q, showing clearly their three‑dimensional structures.  R can be used to make a polymer, W, in two steps. R W addition polymerisation intermediate polymer NaOHDraw one repeat unit of W.  Compound Z, H2C=CHCH3, is produced from R. Z can be used in a two-step process to produce 2-aminopropane. In the first step, Z reacts with HBr to form two products. The structure of the product depends on which intermediate is formed, intermediateI or intermediateII. intermediate I CH3 C H3C H + intermediate II CH3 C H H H H C + Explain why intermediateI is more likely to form than intermediateII. When intermediateI forms, the product of the first step is T. Complete the diagram to show the mechanism for the conversion of Z to T. Include all relevant charges, partial charges, curly arrows and lone pairs. C C H H H Br H CH3 CH3 C H3C H + H3C Br H C T Z CH3  T can then be converted to 2-aminopropane. NH3 ethanol H3C Br H C T CH3 H3C NH2 H C 2-aminopropane CH3 Name the mechanism for this conversion. Compound S, CH3COCO2H, can be reduced by LiAl H4. Complete the equation using structural formulae to represent this reaction. Use to represent the reducing agent. CH3COCO2H + Other reducing agents containing Group1 metal cations include LiBH4, NaBH4 and KBH4. The strength of the reducing agent depends on the size of its cation. Give the electronic configuration of the Na+ cation. 1s2 Suggest why ionic radius increases down Group1. 
9701_w18_qp_22
THEORY
2018
Paper 2, Variant 2
View
An alkene, a carboxylic acid and a ketone, all of similar volatility, are mixed together. The mixture is then analysed by gas chromatography. The gas chromatogram produced is shown. absorption time / mins J K L The separation of the three compounds depends on their relative solubilities in the liquid stationary phase. The liquid stationary phase is an alkane. Complete the table to suggest which compound in the mixture is responsible for each peak J, K and L. Explain your answer by reference to the intermolecular forces of each compound. peak organic compound explanation J K L  A student calculates the areas underneath the three peaks in the chromatogram. peak J K L area / mm2 The area underneath each peak is proportional to the mass of the respective compound. Calculate the percentage by mass in the original mixture of the compound responsible for peak K.  % of mixture responsible for peak K = Chlorobenzene can be prepared from benzene as shown. Cl 2 Cl Al Cl 3 Aluminium chloride, Al Cl 3, catalyses this reaction. Write an equation to show how Al Cl 3 generates the electrophile needed in this reaction. Draw the mechanism of the reaction between this electrophile and benzene to form chlorobenzene. Include all relevant curly arrows and charges.  Write an equation to show how the catalyst is regenerated. Catalysts can be heterogeneous or homogeneous. Explain what is meant by a homogeneous catalyst. Complete the table by placing one tick () in each row to indicate the mode of action of the catalyst in each reaction. heterogeneous homogeneous Rh in the removal of NO2 from exhaust gases of cars Fe3+ in the I – / S2O8 2– reaction  
9701_w18_qp_42
THEORY
2018
Paper 4, Variant 2
View
Questions Discovered
313