Download Experiment: THE EFFECT OF LIGHT ON SILVER HALIDES

Experiment: THE EFFECT OF LIGHT
ON SILVER HALIDES
QUESTIONS
1
Which of the filter papers were affected by exposure?
Silver Chloride (AgCl) and Silver Bromide (AgBr) were the most
affected.
2
Why was the design left on the filter paper?
The design will form where the light was able to decompose the
silver ion into silver atoms.
3
Write a list of compounds in order from least affected to most affected.
AgI is the least sensitive and used in X-ray radiography; AgBr is
moderately sensitive, used in most standard photographic films;
AgCl is the most sensitive forming a black solid
4
Write equations for the reactions which occurred.
2Ag+ + 2Br– → 2Ag(s) + Br2 (g)
2Ag+ + 2I– → 2Ag(s) + I2 (g)
5
Why was the filter paper washed with the sodium thiosulfate solution? Write an equation for
3–
this reaction. (The product is Ag(S2O3)2 .)
After development, the film is "fixed," during which the remaining silver ions
are removed to prevent further decomposition. The agent used is sodium
thiosulphate, and reactions according to the following equation:
AgBr (s) + 2 Na2S2O3(aq) → Na3[Ag(S2O3)2](aq) + NaBr (aq)
With spectator ions removed: 2Ag+ + (S2O3)
2–
→
Ag(S2O3)2
3–
6
Why are silver compounds stored in dark bottles?
It is photosensitive, reacts with light to form a precipitate of
silver.
7
Suggest one use that could be made of these reactions.
To develop photos