In order to determine the chloride concentration in a solution, a Mohr titration is perform. This involves adding a small amount of chromate to the solution and then slowly adding silver nitrate. Silver chloride is pale yellow solid while Silver chromate is a dark red. The appearance of the red silver chromate is the endpoint of the titration. Answer the questions below about this process.
(Ksp of AgCl= 1.7x10^-10 and Ksp of Ag2CrO4= 1.12x10^-12)
A 100 mL sample of water from a potentially contaminated stream is collected. A 0.0010 g of sodium chromate is dissolved in the sample.
1) if the solution had been 0.015 M in NaCl, what percent of the chloride is still in solution?
Given the answer to the question above, it should be clear that "all" of the chloride is removed before the silver chromate appears. This is why we can use it as an endpoint.
2) if it requires 21.4 mL of a 0.1 M solution of silver nitrate to reach the equivalence point with 100 mL of solution, what was the original concentration of chloride? (Remember that the endpoint uses "100%" of the chloride. therefore you can treat this as a simple stoich problem)
3) how many mL of 0.1 M silver nitrate would be needed to titrate 25.06 mL of a 0.0445M solution of KCl?
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