【Daily Question】Chemical Engineering Principles 558: The reason why industrial hydrochloric acid is yellow (May 17)
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The Chemical Engineering Theory section is launching the \"One Question per Day\" campaign starting today, aimed at helping everyone reinforce their basic knowledge in chemical engineering. Subsequent series will include those on \"Principles of Chemical Engineering,\" \"Mass Transfer and Separation,\" \"Thermodynamics in Chemical Engineering,\" and \"Chemical Process Engineering.\" We hope you will give it your active support~~~ Answers to the \"One Question per Day\" questions can be viewed directly here; the topic will be closed after 1 day! ! To encourage everyone’s continued participation this year! Participation earns 3 wealth points, with an additional 4 wealth points for correct answers~~~ Short answer question: What impurity is present in industrial hydrochloric acid that causes it to be yellow? Iron ions
Industrial hydrochloric acid turns yellow due to the presence of iron chloride impurities. To remove iron chloride, taking advantage of the volatility of hydrochloric acid, distillation can be used to separate hydrogen chloride from it; since iron chloride is not volatile, the gas obtained through distillation can then be dissolved in water to yield pure hydrochloric acid
Ferric chloride, when dissolved in water, causes the solution to turn yellow.
Industrial hydrochloric acid is yellow because it contains Fe3+ iron ions