11.5. Alkenes
A subsection of Chemistry, 0620, through 11. Organic chemistry
Listing 10 of 149 questions
The alkenes are unsaturated hydrocarbons. They form a homologous series, the members of which have the same chemical properties. They undergo addition reactions and are easily oxidised. The following hydrocarbons are isomers. CH3 CH3 CH2 CH CH CH3 CH2 CH2 CH2 CH Explain why these two hydrocarbons are isomers. Give the structural formula of another hydrocarbon which is isomeric with the above. Give the structural formula and name of each of the products of the following addition reactions. ethene and bromine structural formula of product name of product propene and hydrogen structural formula of product name of product but-1-ene and water structural formula of product name of product Alkenes can be oxidised to carboxylic acids. For example, propene, CH3 – CH = CH2, would produce ethanoic acid, CH3 – COOH, and methanoic acid, H – COOH. Deduce the formulae of the alkenes which would form the following carboxylic acids when oxidised. ethanoic acid and propanoic acid only ethanoic acid Describe the colour change you would observe when an alkene is oxidised with acidifi ed potassium manganate(. Alkenes polymerise to form addition polymers. Draw the structural formula of poly, include at least two monomer units. The structural formula of the monomer, cyanoethene, is given below. C C H CN H H
0620_w13_qp_31
THEORY
2013
Paper 3, Variant 1
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Bromine is a red-brown liquid which is soluble in cyclohexane. A few drops of liquid bromine were placed at the bottom of a beaker containing cyclohexane. After 3 days, a red-brown colour had spread throughout the beaker. at the start after 6 hours after 3 days cyclohexane bromine Explain these observations using the kinetic particle model. The structure of a compound containing bromine is shown. H C H Br Br C H C C O O H H H Deduce the molecular formula of this compound showing the number of carbon, hydrogen, oxygen and bromine atoms. State the name of the C O O H functional group. The relative atomic mass of bromine is 80. Complete the definition of relative atomic mass using terms from the list. an atom an element a molecule average carbon hydrogen total Relative atomic mass is the mass of naturally occurring atoms of on a scale where of the 12C isotope has a mass of exactly units. Dilute hydrobromic acid reacts with magnesium ribbon. Suggest three ways of increasing the rate of this reaction. Hydrobromic acid reacts with oxygen. The products are water and bromine. Balance the chemical equation for this reaction. HBr + O2 2H2O + 2Br2
0620_w17_qp_31
THEORY
2017
Paper 3, Variant 1
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Alkenes and carboxylicacids are both families of similar compounds with similar chemical properties. Alkenes and carboxylicacids have different reactions. State the term used for a ‘family’ of similar compounds. State the general formula of alkenes. The structure of but-2-ene is shown. H C H H C H C C H H H H But-2-ene reacts with aqueous bromine in an addition reaction. Describe the colour change seen when but-2-ene is added to aqueous bromine. from to State what is meant by the term addition reaction. Write the chemical equation for the reaction between but-2-ene and bromine. But-2-ene forms a polymer. Suggest the name of the polymer formed from but-2-ene. Name and draw a structural isomer of but-2-ene. Show all of the atoms and all of the bonds. name structure  Butanoic acid, CH3CH2CH2COOH, is a carboxylicacid. Deduce the empirical formula of butanoicacid. Complete the chemical equation for the reaction of butanoicacid and sodiumcarbonate, Na2CO3. 2CH3CH2CH2COOH + Na2CO3 → + +  Butanoicacid reacts with methanol to form an organic compound and water. ● Name the organic compound formed. ● Draw the structure of the organic compound formed. Show all of the atoms and all of the bonds.  
0620_w21_qp_41
THEORY
2021
Paper 4, Variant 1
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Questions Discovered
149