# How do silver ions interact with halide ions? How can the presence of ammonium in aqueous solution be evidenced?

##### 1 Answer
Mar 22, 2017

$A {g}^{+} + C {l}^{-} \rightarrow A g C l \left(s\right) \downarrow$

#### Explanation:

Of course, the equation presupposed the ABSENCE of other metal ions that form insoluble halides, i.e. we assume the absence of $P {b}^{2 +}$, and $H {g}_{2}^{2 +}$ ions.............

For ammonium ions, we could exploit the acid-base properties of ammonium cation:

$N {H}_{4}^{+} + H {O}^{-} \rightarrow N {H}_{3} \left(g\right) \uparrow + {H}_{2} O \left(l\right)$

The odour of ammonia is unmistakable. Ammonium forms an insoluble tetraphenylborate, $N {H}_{4} B P {h}_{4}$, but tetraphenylborate salts are VERY expensive, and tend not to be used in this scenario.