Questão de Natural Sciences and their Technologies #019e354b
O magnésio metálico utilizado em ligas leves é produzido em um processo que envolve várias etapas e utiliza água do mar como matéria-prima. A primeira etapa desse processo consiste na reação entre o íon Mg2+ e hidróxido de cálcio, Ca(OH)2, obtendo uma mistura que contém hidróxido de magnésio, pouco solúvel, e íons Ca2+, de acordo com a equação química:
Mg2+ (aq)+Ca(OH)2 (aq)→Mg(OH)2 (s)+Ca2+ (aq)
O método adequado para separar o Mg(OH)2 dessa mistura é a
filtration.
picking.
distillation.
dissolution.
evaporation.
Explicação Oficial / Explicações da Comunidade
Analysis of the Magnesium Hydroxide Separation Process
The correct answer is option A. A) filtration.
1. Identifying the Nature of the Mixture
The question describes the final stage of a chemical process, which results in a mixture. To choose the correct separation method, we need to analyze the components of this mixture and their physical states, according to the given chemical equation:
Mg²⁺(aq) + Ca(OH)₂(aq) → Mg(OH)₂(s) + Ca²⁺(aq)
The final mixture consists of:
- Magnesium hydroxide - Mg(OH)₂ (s): The notation (s) indicates that this compound is in the state solidThe statement also reinforces that it is "slightly soluble," meaning that it forms as a solid precipitate in the solution. 2. Calcium ions - Ca²⁺ (aq): The notation (aq) indicates that these ions are aqueousThat is, dissolved in water, which serves as the solvent for the reaction.
Therefore, we have a heterogeneous mixture, consisting of a phase solid (the Mg(OH)₂ precipitate) disperses in a phase liquid (an aqueous solution containing Ca²⁺ ions and other components).
2. Evaluation of Separation Methods
The goal is to separate the solid component (Mg(OH)₂) from the liquid component. Let's analyze the options:
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A) Filtration: This is the standard method for separating a insoluble solid of a liquid. The mixture is passed through a porous medium (a filter), which retains the solid particles while allowing the liquid to pass through. This is the perfectly suitable technique for the situation described.
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B) Sorting: It is a manual method for separating visibly different solids (e.g., selecting good beans from bad ones). It does not apply to a fine precipitate in a liquid.
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C) Distillation: It is used to separate liquids with different boiling points or a liquid from a dissolved solid (when the goal is to recover the liquid). It is not the most direct or efficient method for separating an undissolved solid.
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D) Dissolution: It is the act of dissolving a solid in a liquid to form a solution, not a separation method in this context.
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E) Evaporation: It is used to separate a dissolved solid from a solvent, discarding the solvent (e.g., obtaining salt from seawater). If applied here, the water would evaporate, but the Ca²⁺ ions and other soluble salts would remain mixed with the Mg(OH)₂, not achieving the desired separation.
3. Conclusion
Given that the task is to separate solid magnesium hydroxide from an aqueous solution, the most suitable and direct method is: filtration.