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Alcohols, haloalkanes and analysis

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Question 21

Cyclohexanol can be dehydrated to form cyclohexene in the presence of an acid catalyst, such as concentrated phosphoric acid.

Cyclohexene is a liquid with a boiling point of 83 ∘C83\text{ }^\circ\text{C}83 ∘C and a density of 0.81 g cm−30.81\text{ g cm}^{-3}0.81 g cm−3. Cyclohexanol has a boiling point of 161 ∘C161\text{ }^\circ\text{C}161 ∘C.

A student plans to prepare 5.50 g5.50\text{ g}5.50 g of cyclohexene. The expected percentage yield is 60.0%60.0\%60.0%.

The molar mass of cyclohexanol is 100.0 g mol−1100.0\text{ g mol}^{-1}100.0 g mol−1 and cyclohexene is 82.0 g mol−182.0\text{ g mol}^{-1}82.0 g mol−1.

a.

Calculate the mass of cyclohexanol that the student should use, writing your answer to 3 significant figures.

[3]
b.

Describe and explain the key steps to obtain a pure, dry sample of cyclohexene from the reaction mixture distillate, which contains both aqueous and organic layers.

[4]
c.

The IR spectrum of the organic layer from the distillate shows a broad peak at 3200–3600 cm−13200\text{--}3600\text{ cm}^{-1}3200–3600 cm−1 and a sharp peak at 1620–1680 cm−11620\text{--}1680\text{ cm}^{-1}1620–1680 cm−1. Explain what each of these peaks indicates about the progress of the reaction.

[2]

Alcohols, haloalkanes and analysis Questions

  1. A Level
  2. /Chemistry
  3. /Alcohols, haloalkanes and analysis