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This question is about the preparation of hexan-2-ol - AQA - A-Level Chemistry - Question 5 - 2022 - Paper 2

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This question is about the preparation of hexan-2-ol. Hexan-2-ol does not mix with water and has a boiling point of 140 °C Hexan-2-ol can be prepared from hex-1-ene... show full transcript

Worked Solution & Example Answer:This question is about the preparation of hexan-2-ol - AQA - A-Level Chemistry - Question 5 - 2022 - Paper 2

Step 1

Suggest, with a reason, one other appropriate safety precaution for this experiment.

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Answer

Wear gloves.

Reason: Gloves protect against spills and contact with corrosive substances, such as concentrated phosphoric acid.

Step 2

Give a reason for adding the distilled water in steps c and f.

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Answer

To remove water-soluble impurities and to ensure a complete reaction with the excess acid.

Step 3

Give a reason for adding anhydrous magnesium sulfate in step h.

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Answer

To dry the organic layer by absorbing any remaining water in the distillate.

Step 4

Complete and label the diagram of the apparatus used to filter the mixture under reduced pressure in step i.

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The apparatus includes a round-bottom flask connected to a vacuum pump through a vacuum adapter. Label the flask and the connection to the vacuum pump.

Step 5

Identify the most likely organic impurity, other than hex-1-ene, in the distillate collected in step j.

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Answer

Impurity: Hexan-3-ol.

Reason: It is likely to have a similar boiling point to hexan-2-ol, making it difficult to separate during distillation.

Step 6

Calculate the mass, in g, of hexan-2-ol formed from 11.0 cm³ of hex-1-ene if the yield is 31.0%.

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Answer

First, calculate the moles of hex-1-ene:

extDensityofhex1ene=0.678extg/cm3 ext{Density of hex-1-ene} = 0.678 ext{ g/cm}^3

Mass of hex-1-ene: 11.0extcm3imes0.678extg/cm3=7.458extg11.0 ext{ cm}^3 imes 0.678 ext{ g/cm}^3 = 7.458 ext{ g}

Molar mass of hexan-2-ol: C6H14O=100.16extg/molC_6H_{14}O = 100.16 ext{ g/mol}

Moles of hexan-2-ol produced (theoretical): ext{moles} = rac{7.458 ext{ g}}{84.16 ext{ g/mol}} = 0.0885 ext{ moles}

Actual yield of hexan-2-ol: 0.0885extmolesimes0.31=0.0274extmoles0.0885 ext{ moles} imes 0.31 = 0.0274 ext{ moles}

Mass of hexan-2-ol produced: 0.0274extmolesimes100.16extg/mol=2.75extg0.0274 ext{ moles} imes 100.16 ext{ g/mol} = 2.75 ext{ g}

Thus, the final answer is: 2.8 g.

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