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Hydrogen — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistryHydrogen5 Marks
Question
Do you expect different products in solution when aluminium (III) chloride and potassium chloride treated separately with:
  1. Normal water.
  2. Acidified water, and
  3. Alkaline water? Write equations wherever necessary.
✓

Answer

  1. In normal water,
$\text{AlCl}_3+3\text{H}_2\text{O}\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ }\text{Al(OH)}_3+3\text{HCl}$

KCl will dissolve in water and ions will get hydrated.
  1. KCl will be unaffected in acidified water. While in acidic water $\mathrm{H}^{+}$ion react with $\mathrm{Al}(\mathrm{OH})_3$ to form $\mathrm{Al}^{3+}(\mathrm{aq})$ ions and $\mathrm{H}_2 \mathrm{O}$. Thus in acidic water $\mathrm{AlCl}_3$ existes as $\mathrm{Al}^{3+}(\mathrm{aq})$ and $\mathrm{Cl}^{-}(\mathrm{aq})$ ions,
$\text{AlCl}_3(\text{s})\xrightarrow{\ \ \ \ \ \ {\text{Acidified}} \ \ \ \ \ \ \ \ }\text{Al}^{3+}(\text{aq})+3\text{Cl}^-(\text{aq})$
  1. In alkaline water since the aqueous solution of $KCl$ is neutral therefore, it is unaffected.
$Al(OH)_3$ reacts to form soluble tetrahydroxoaluminate complex or meta-aluminate.

$\text{AlCl}_3(\text{s})\xrightarrow{\ \ \ \ \ \ {\text{Alkaline}\\ \text{ water}} \ \ \ \ \ \ \ \ }\text{Al}^+\big[(\text{OH})_4\big]^-+3\text{Cl}^-\text{OH}^-\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \downarrow\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \text{AlO}_2 ^-(\text{aq) }2\text{H}_2\text{O(l)}+3\text{Cl}^-(\text{aq})$

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