A chemist needs to recover solid solutes separately from two aqueous mixtures: Solution X containing sodium chloride () to obtain anhydrous salt, and Solution Y containing hydrated iron(II) tetraoxosulfate(VI) () to obtain pure hydrated crystals. Which combination of techniques should be used to obtain the solutes from Solution X and Solution Y respectively?
- Evaporation to dryness for Solution X, and crystallization for Solution YCevap
- BCrystallization for Solution X, and evaporation to dryness for Solution Y
- CEvaporation to dryness for both Solution X and Solution Y
- DFiltration for Solution X, and simple distillation for Solution Y
Cevap
Evaporation to dryness for Solution X, and crystallization for Solution Y
The correct response identifies that sodium chloride solution can be safely evaporated to dryness because the salt is heat-stable and has no water of crystallization to preserve. Conversely, hydrated iron(II) tetraoxosulfate(VI) requires crystallization (partial evaporation to a saturated state followed by cooling) to retain its water of crystallization and avoid thermal decomposition.
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Anahtar Kavram
Selecting evaporation to dryness versus crystallization based on thermal stability and water of crystallization