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A professor I have gave the class this question, can anyone help? This is the first part of the question. (Also, my professor is from Bangladesh...so yea...)

It's the year 2395, and the world is in chaos. Two nations have conquered the world, USA and Bangladesh. You have been hired by Bangladesh's government to monitor acid baths used to remove oxidation on aerospace metallic material desperately needed for the new F-95 fighter jet engine.

The acid bath is made up of three components:

25-30% HNO3 4-5% HF Balance H2O

Unfortunately, a spy has broken into your facility and added large amounts of Chlorine to the acid bath. As the lead chemist, it is your job to determine how much Chlorine was added to the acid bath.

During sample collection, it is uncertain what any of the concentrations are, however once a sample is obtained you may manipulate it with any method you wish. Devise a method to determine the concentration of chlorine in the solution.

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The addition of chlorine to the bath will produce hydrochloric acid. If the chloride ion concentration in the bath sample could be determined, then you could back-calculate to the amount of hydrochloric acid added. The standard method to determine the amount of chloride ion in an aqueous sample is to precipitate it by adding silver nitrate solution followed by collecting the precipitate by filtration and then drying and weighing it. You could use that approach here because silver nitrate and silver fluoride (which would be created from silver nitrate and the hydrofluoric acid) are soluble* in water, so only the silver chloride would precipitate if silver nitrate were added to your acid bath sample. Here's a link to an actual gravimetric procedure for determining chloride ion content.

  • Note: silver fluoride is soluble to the extent of 1.8 kg/L, therefor silver fluoride should not precipitate upon addition of silver nitrate to your chlorine-contaminated sample because the hydrofluoric acid content of the bath was only 4-5%.
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  • $\begingroup$ Nice answer however I was wondering isn't this question off topic? Since it's a homework question and no work on part of the OP is shown $\endgroup$ – StackUpPhysics Aug 24 at 19:46
  • $\begingroup$ Just saw the year it was asked I saw it today while searching for something maybe the rules have changed $\endgroup$ – StackUpPhysics Aug 24 at 19:47
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I would suggest some form of multi-step redox titration. You'll need values for electrode potentials though.

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