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Zorluk: OrtaTypes and Preparation Methods of Salts

A chemist needs to prepare a pure, hydrated sample of copper(II) tetraoxosulfate(VI) (CuSO4⋅5H2OCuSO_4 \cdot 5H_2O) starting from insoluble copper(II) oxide (CuOCuO). Which of the following experimental procedures is correct for this preparation?

  1. Add excess copper(II) oxide to dilute tetraoxosulfate(VI) acid, filter the mixture, concentrate the filtrate, and allow it to cool for crystallization.Cevap
  2. B
    Mix aqueous copper(II) nitrate with aqueous sodium tetraoxosulfate(VI), filter off the precipitate formed, and dry it in an oven.
  3. C
    Titrate copper(II) oxide solution against dilute tetraoxosulfate(VI) acid using phenolphthalein, then evaporate the liquid to complete dryness.
  4. D
    Dissolve copper(II) oxide in hot distilled water, add sodium chloride solution, and collect the resulting salt crystals.

Cevap

The correct procedure is to react excess insoluble copper(II) oxide with dilute tetraoxosulfate(VI) acid, filter out the unreacted solid, concentrate the filtrate by gentle heating, and cool to form crystals.
The standard method for preparing a soluble salt from an insoluble oxide involves adding excess oxide to hot dilute acid to ensure complete acid neutralization, filtering out the unreacted solid, and partially evaporating the filtrate so that hydrated crystals form upon cooling.

Adım Adım Çözüm

1
Identify the solubility of the product salt and reactants
Copper(II) tetraoxosulfate(VI) (CuSO4CuSO_4) is a soluble salt, while copper(II) oxide (CuOCuO) is an insoluble base.
Soluble salts prepared from insoluble bases require the excess insoluble reactant method.
2
Neutralize dilute acid with excess insoluble base
Warm H2SO4(aq)H_2SO_4(aq) reacts with excess CuO(s)CuO(s) according to: CuO(s)+H2SO4(aq)→CuSO4(aq)+H2O(l)CuO(s) + H_2SO_4(aq) \rightarrow CuSO_4(aq) + H_2O(l).
Using excess base ensures all acid is fully consumed.
3
Separate unreacted solid and crystallize
Filter off unreacted CuOCuO, heat the filtrate to crystallizing point, and cool slowy to obtain hydrated crystals (CuSO4⋅5H2OCuSO_4 \cdot 5H_2O).
Filtration removes insoluble excess, and gentle cooling preserves water of crystallization.

Anahtar Kavram

Preparation of soluble salts using dilute acids and insoluble bases
Tahmini Süre:1m 30s
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Konular

Types and Preparation Methods of Salts

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