Precipitation Reactions

Common Ion Effect

The addition of concentrated hydrochloric acid to a saturated solution of sodium chloride causes solid sodium chloride to precipitate out.

Fehling Test

When blue Fehling's reagent is added to glucose and fructose solution a brick-red precipitate forms - no rxn with sucrose.
Fehling Test

Zinc Complex Ion Formation

Zinc ion is precipitated by sodium hydroxide. The addition of more hydroxide redissolves the precipitate.

Copper-Ammonia Complex

Copper chloride solution forms a pale blue precipitate then a deep blue solution as ammonia is added.
Copper Hydroxide

Aldol Clock

A solution of cinnamaldehyde and acetone suddenly turns bright yellow after induction period.
Aldol Clock

Precipitation of Lead(II) Iodide

When lead(II) nitrate and potaasium iodide are mixed in water, students observe the formation of a bright yellow precipitate, lead(II) iodide.
Precipitation of lead(II) iodide


© Copyright 2012 Email: Randy Sullivan, University of Oregon Chemistry Department and UO Libraries Interactive Media Group