WAEC - Chemistry (2001 - No. 34)
Which of the following reactions represents the change that occurs when a photographic film is exposed to sunlight?
Ag → Ag+ + e-
Ag+ + e- → Ag
2Ag + Br22 → AgBr
Ag+ + Br- → AgBr
Uitleg
When photographic film is exposed to sunlight, it undergoes a chemical reaction that converts light energy into chemical energy. This reaction causes the film to change chemically and appear black, spoiled, or unable to be developed.The silver bromide in the film breaks down into silver grains. The film produces free silver, which appears as black spots.
The chemical equation for this reaction is:
- 2 AgBr → 2 Ag + Br2 Ag gains an electron to become reduced to Ag metal. -Option B