Give equations and describe the process for the developing of black and white photographic film. When sodium thiosulphate solution is treated with acidic solution turns milky white. Give the half reaction of the above described process.
Text Solution
Verified by ExpertsCHECK THE SOLUTION.
Developer is usually a weak reducing agent like potassium ferrous oxalate, an alkaline solution of pyrogallol or an alkaline solution of quinol.
In the process of development of the photographic film, the exposed/activated AgBr grains are preferentially reduced by one of the reducing agent described above.
HO 
HO 
O 
O + 2e – + 2H +
Hydroquinone Quinone
AgBr + e – 
Ag(s) + Br –
The photographic film is then fixed by washing with hypo solution to remove the unreduced AgBr grains from the film.
AgBr + 2Na 2 S 2 O 3 
Na 3 [Ag(S 2 O 3 ) 2 ] + NaBr.
S 2 O 3 2– + H 2 O 
2SO 2 + 2H + + 4e – .
S 2 O 3 2– + 6H + 
2S ↓ (white milky) + 3H 2 O.
Prepare Smarter with CGP Edu
Get practice questions, solutions, and test series in one place.
Write a Review
Share your experience with this question and solution.
Commentary
Send your comment, doubt, correction, or feedback to admin.
Similar Questions
Explore conceptually related problems