1.1. Compound B contains carbon, hydrogen and oxygen only.

It has the following percentage composition by mass: C 54.5%, H 9.1%, O 36.4%.

Calculate the empirical formula of B.

Show your working.

Empirical formula =

1.2. Compound C is the secondary alcohol, butan-2-ol, CH₃CH(OH)CH₂CH₃.

i) Butan-2-ol can be converted into but-2-ene by dehydration.

State the reagent and conditions required for this reaction.

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ii) Butan-2-ol is heated under reflux with acidified potassium dichromate(VI).

State the colour change observed.

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iii) Name the organic product formed in (b)(ii).

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1.3. But-2-ene exhibits geometrical (cis–trans) isomerism.

i) Explain the term geometrical isomerism.

In your answer, refer to the features of the double bond and the groups attached to it.

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ii) Draw the displayed formula of trans-but-2-ene.

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iii) Describe a chemical test to show the presence of the C=C double bond in but-2-ene.

Reagent: ………………………………………

Observation: …………………………………

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1.4. Infrared spectroscopy is used to identify functional groups.

Use the Data Booklet to identify the bond responsible for the following absorption peaks found in organic spectra.

i) A strong absorption peak at 1700 cm⁻¹.

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ii) A broad absorption peak in the range 3200–3600 cm⁻¹.

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iii) State how the infrared spectrum of the product formed in (b)(iii) would differ from the spectrum of butan-2-ol.

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