For Redox Analysis of Iron... ~0.02 M of potassium dichromate is prepared as titrant for dried unknown. ~.3 g of sample, 50ml of 6M HCl, 20mL SnCl2, 10 mL of saturated HgCl2 solution, 60 mL of 3M H2SO4, 15mL of concentrated H3PO4, 100mL DI water. HCl (+ heat in fumehood until samples dissolves), SnCl2 (added with pipet until solution changes from yellow to colorless/light green with 3 drops in excess), HgCl2 (after cooling), H2SO4, H3PO4, DI Water, is added to the sample solution with 8 drops of diphenylamine sulfonate indicator then titrated with the potassium dichromate to a violet blue endpoint. 1. What is the purpose of the phosphoric acid in this experiment? Please be specific. 2. How does the Diphenylamine sulfonate indicator work? What chemical reaction causes the color change? How is an indicator chosen in a redox reaction?
For Redox Analysis of Iron...
~0.02 M of potassium dichromate is prepared as titrant for dried unknown.
~.3 g of sample, 50ml of 6M HCl, 20mL SnCl2, 10 mL of saturated HgCl2 solution, 60 mL of 3M H2SO4, 15mL of concentrated H3PO4, 100mL DI water.
HCl (+ heat in fumehood until samples dissolves), SnCl2 (added with pipet until solution changes from yellow to colorless/light green with 3 drops in excess), HgCl2 (after cooling), H2SO4, H3PO4, DI Water, is added to the sample solution with 8 drops of diphenylamine sulfonate indicator then titrated with the potassium dichromate to a violet blue endpoint.
1. What is the purpose of the phosphoric acid in this experiment? Please be specific.
2. How does the Diphenylamine sulfonate indicator work? What
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