Chemistry – Experimental techniques and chemical analysis - Separation and purification | e-Consult
Experimental techniques and chemical analysis - Separation and purification (1 questions)
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A suitable method is precipitation followed by filtration.
Procedure:
- Add a dilute solution of sodium carbonate (Na2CO3) to the solution. This will react with the copper(II) ions to form a copper(II) carbonate precipitate. The balanced equation is: Cu2+(aq) + CO32-(aq) → CuCO3(s)
- Allow the precipitate to settle.
- Filter the solution to remove the solid copper(II) carbonate.
- Dissolve the copper(II) carbonate precipitate in dilute hydrochloric acid (HCl). This will convert the copper(II) carbonate to copper(II) chloride. The balanced equation is: CuCO3(s) + 2HCl(aq) → CuCl2(aq) + H2O(l) + CO2(g)
- Filter the solution to remove any insoluble impurities.
- Evaporate the water to obtain solid copper(II) chloride.
Scientific Principles:
- Precipitation: The formation of an insoluble solid (the copper(II) carbonate) from the solution. The solubility product (Ksp) of copper(II) carbonate is low, so it readily precipitates.
- Filtration: Separating the solid precipitate from the liquid solution using a filter paper.
- Acid-Base Reaction: The reaction of the copper(II) carbonate with hydrochloric acid to regenerate copper(II) chloride in solution.