Question

Explain the difference between a double salt and a complex salt.

Hint:

Double salts dissociate completely; complex salts give stable complex ions in solution.

Answer 1

Step 1: Definition of Double Salt.
A double salt is formed by the combination of two simple salts in a definite proportion that crystallize together. In aqueous solution, it completely dissociates into its constituent ions.
Step 2: Definition of Complex Salt.
A complex salt consists of a central metal ion bonded to one or more ligands. It does not dissociate completely in water but gives a complex ion.
Step 3: Example.
- Double Salt: \( \text{Mohr's salt } (FeSO_4 \cdot (NH_4)_2SO_4 \cdot 6H_2O) \) dissociates completely into \( Fe^{2+}, NH_4^+, \) and \( SO_4^{2-} \).
- Complex Salt: \( K_4[Fe(CN)_6] \) does not dissociate completely; it gives complex ion \( [Fe(CN)_6]^{4-} \).
Step 4: Key Difference Table.
\begin{tabular}{|p{4cm}|p{5cm}|} \hline Double Salt & Complex Salt
\hline Completely dissociates in water & Partially dissociates, forms complex ion
\hline Exists only in solid state & Exists in solution as complex ions
\hline Example: Mohr's salt & Example: Potassium ferrocyanide
\hline \end{tabular}