A square photographic film 2.00 cm on an edge was suspended in a 5% solution of Na2S2O3 to form a Ag(S2O3)2^3- complex and release the halide. After removal and washing of the film, the solution was treated with an excess of Br2 in basic solution to oxidize the I^- to IO3^- (and also to destroy the excess S2O3^2-). The solution was boiled to remove the Br2, and an excess of KI was added. The liberated I2 was titrated with 13.7 mL of 0.0352 M Na2S2O3 solution (the products are S4O6^2- and I^-).

a) Write balanced equations for the reactions of interest.
b) Calculate the mg of AgI per cm^2 of film.

--> I have no clue where my professor came up with the equations for part A, nor how he calculated the mg/cm^2.

asked by Jed

6 years ago

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A square photographic film 2.00 cm on an edge was suspended in a 5% solution of Na2S2O3 to form a Ag(S2O3)2^3- complex and release the halide.  After removal and washing of the film, the solution was treated with an excess of Br2 in basic solution to oxidize the I^- to IO3^- (and also to destroy the excess S2O3^2-).  The solution was boiled to remove the Br2, and an excess of KI was added.  The liberated I2 was titrated with 13.7 mL of 0.0352 M Na2S2O3 solution (the products are S4O6^2- and I^-).
a)  Write balanced equations for the reactions of interest.
b)  Calculate the mg of AgI per cm^2 of film.

--> I have no clue where my professor came up with the equations for part A, nor how he calculated the mg/cm^2.