Photosensitivity of silver chloride

Object contour is drawn by light.

Scientific name: Photosensitive silver chloride decomposes when exposed to ultraviolet light.


Cool Science: Silver Chloride Photochemistry

Photosensitivity of silver chloride

Silver chloride photography

by chemistry858


Wear eye protection goggles and gloves. Perform this experiment in a fume hood.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

AgNO3 + HCl → AgCl ↓+ HNO3

2AgCl -light → 2Ag + Cl2

Step-by-step instruction

  1. To prepare silver chloride mix together solutions of silver nitrate and hydrochloric acid.
  2. A white precipitate forms.
  3. Filter the solution. Put a funnel with filter paper in an empty beaker. Pour the solution through the funnel.
  4. Dry the precipitate. Put it into the petri dish and cover it with foil in order to prevent light incidence.
  5. When the precipitate becomes dry remove the foil.
  6. Put any opaque object, such as a key, on the top of the substance.
  7. Use a burning magnesium ribbon as the ultraviolet light source.
  8. White powder of silver chloride turns grey except for the place covered by the key. This area remains white.

Scientific background

Silver chloride is a photosensitive substance. When it is exposed to light it decomposes with the formation of elemental silver. The ultraviolet light obtained from the burning magnesium ribbon is very intense and the process passes very fast. The effect of common light will be the same but the reaction speed will be much lower. The effect of photosensitivity of silver halide was used in photography. The silver chloride emulsion in gelatin solution was coated on to a film base. Since different areas of film receive different amounts of light it allows getting the image.


Published on 14 May 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst