Chemistry mark scheme
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The rate equation for a reaction is rate = k[E] Explain qualitatively why raising the temperature by 10 °C has a much greater effect on the rate of the reaction than doubling the concentration of E. [3 marks]
Reaction occurs when molecules have E≥Ea Raising T by 10 °C causes many more molecules to have this E Whereas doubling [E] only doubles the number with this
Alcohol A (CH3)2CHCH(OH)CH3 undergoes reactions separately with acidified potassium dichromate(VI) and with concentrated sulfuric acid. Deduce the IUPAC name for alcohol A. (1)
3-methylbutan-2-ol
Butanone is reduced in a two-step reaction using NaBH4 followed by dilute hydrochloric acid. Write an overall equation for the reduction of butanone using [H] to represent By considering the mechanism of the reaction, explain why the product has no effect on plane polarised light.esent the reductant. (6)
Indicative Chemistry content Stage 1: Formation of product * Nucleophilic attack * Planar carbonyl group * H– attacks from either side (stated or drawn) Stage 2: Nature of product * Product of step 1 shown * This exists in two chiral forms (stated or drawn) * Equal amounts of each enantiomer/racemic mixture formed Stage 3: Optical activity * Optical isomers/enantiomers rotate the plane of polarised light equally in opposite directions * With a racemic/equal mixture the effects cancel
Name the mechanism when H-Br reacts but-1-ene
Electrophilic addition