concentration of chlorine

tolypine · Posted: Tue May 10, 2005 11:19 am Post subject: concentration of chlorine

I have being given a task to determine the concentration of a saturated aqueous solution of chlorine. The question is as follows:

The concentration of a saturated aqueous solution of chlorine (approximately 7g dm3) can be determined by a back titration method.

In the first stage of the procedure, the solution of chlorine is added to an excess suitable reducing agent such as iron(II) compound.

In the second stage the amount of reducing agent left over is determined by titration.

Plan and describe a procedure that could be used safely to determine the exact concentration of saturated aqueous solution of chlorine by back titration. Can anyone please help me with this task. i dont know how to write up the procedure

RobJim · Posted: Tue May 10, 2005 10:14 pm Post subject:

Here's the basic idea.

You carefully determine the exact number of moles of iron(II) you have in your solution. Then you determine the exact volume of the chlorine solution.

Next, mix the two together.

Then, find some reagent that will let you determine the amount of iron(II) you have left via titration. Once you know this, you subtract the amount of iron(II) you have left from the original amount of iron(II). This tells you how much iron (II) got reacted off by the chlorine.

Then, use the chemical equation for chlorine reacting with iron(II) to determine how much chlorine there was. Then divide the chlorine content by the original volume of chlorine solution to get the concentration you're looking for.