Silver halide precipitates

You should have observed the following three colours of precipitates:


silver chloride - white	silver bromide - cream	silver iodide - pale yellow

You should notice that the colours aren't particularly different, so it helps to have a further test to distinguish them. We use the solubility in ammonia solution. Again you need to remember the results:

Silver chloride is soluble in dilute or concentrated ammonia solution

Silver bromide is sparingly soluble in dilute ammonia, but dissolves in concentrated ammonia

Silver iodideis insoluble in either dilute or concentrated ammonia solution

The final point of interest is that the silver halides are affected by light. The photochemical reaction produces metallic silver which changes the precipitate colour. Consequently, they are used in some photographic materials. More memory required here. Place your mouse over the images to see the effect of brief exposure to light:


AgCl - goes purple	AgBr - goes green	AgI - no visible effect

In order to form a precipitate we need to mix two solutions - one containing the silver ions and the other containing the halide ions. You should understand the principle behind precipitation, and be able to write full and ionic equations for this process. Suggest full and ionic equations for the formation of the three silver halide precipitates. Check your answers here.

In summary:

Precipitate	Colour	Solubility in ammonia (aq)	Change in light
Silver chloride	white	very soluble	goes purple
Silver bromide	cream	slightly soluble	goes green
Silver iodide	pale yellow	insoluble	none observed