HardChemistryHigh School (11–12)Organic Chemistry: Some Basic Principles and Techniques › Purification and Analysis of Organic CompoundsNumericalA-Level IB NEET

Aniline, M = 93 g/mol, is steam distilled…

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Aniline, $M = 93\ \text{g/mol}$ , is steam distilled. The mixture boils when the vapour pressures are about $720\ \text{mm Hg}$ for water and $40\ \text{mm Hg}$ for aniline. Find the mass of aniline that comes over for each gram of water, and the mass of aniline that comes over with $250\ \text{g}$ of water. Take $M = 18\ \text{g/mol}$ for water.

Need a reminder? The key ideaShow

Purification: sublimation (a solid that turns to vapour and back), crystallisation (hot saturated solution, then cooling), distillation (simple, fractional, under reduced pressure, steam) and differential extraction. Chromatography separates by different clinging to a stationary phase, and $R_f = \dfrac{d_s}{d_f}$ , the distance moved by the substance over the distance moved by the solvent front. In steam distillation, $\dfrac{w_1}{w_2} = \dfrac{p_1 M_1}{p_2 M_2}$ .

The worked solution

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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

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