A 10.0 g sample of a mixture of 2‑butanol (C_{4}H_{10}O, M = 74.12 g·mol^{-1}) and tert‑butyl alcohol (C_{4}H_{10}O, M = 74.12 g·mol^{-1}) is heated with excess concentrated H_{2}SO_{4}. Only the secondary alcohol (2‑butanol) undergoes acid‑catalysed dehydration to give but‑2‑ene (C_{4}H_{8}, M = 56.11 g·mol^{-1}) according to the equation:
C_{4}H_{10}O ightarrow C_{4}H_{8} + H_{2}O.
The reaction is carried out to completion with 100 % yield for the dehydration of 2‑butanol, and 0.80 g of but‑2‑ene is isolated.
(a) Determine the mass percent of 2‑butanol in the original mixture.
(b) Calculate the mass of water formed in the reaction.

Question

A 10.0 g sample of a mixture of 2‑butanol (C_{4}H_{10}O, M = 74.12 g·mol^{-1}) and tert‑butyl alcohol (C_{4}H_{10}O, M = 74.12 g·mol^{-1}) is heated with excess concentrated H_{2}SO_{4}. Only the secondary alcohol (2‑butanol) undergoes acid‑catalysed dehydration to give but‑2‑ene (C_{4}H_{8}, M = 56.11 g·mol^{-1}) according to the equation:
C_{4}H_{10}O ightarrow C_{4}H_{8} + H_{2}O.
The reaction is carried out to completion with 100 % yield for the dehydration of 2‑butanol, and 0.80 g of but‑2‑ene is isolated.
(a) Determine the mass percent of 2‑butanol in the original mixture.
(b) Calculate the mass of water formed in the reaction.

Accepted Answer

Mass % of 2‑butanol = 10.6\%; mass of water formed = 0.257 g

Neco 2019 Chemistry Question 24

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