[lingo_belle]

Dear all,

I'll need to prepare 200ppm of sodium hypochlorite solution. Any idea how am I going to do so? Do I need to determine the free chlorine concentration in my concentrated sodium hypochlorite before determining the volume to draw and dilute to my desired vol?

Thanks in advance! 

belle

[Arkcon]

For starters, that would depend on if you're supposed to prepare a "200 ppm sodium hypochlorite solution", or a "sodium hypochlorite solution, such that the hypochlorite is 200 ppm."  It really does depend on how your protocol is written.

[Fleaker]

What Arkcon said is particularly cogent!

Think carefully on what all may be present with hypochlorite in solution. What species are present?

Recall that sodium hypochlorite does not exist as a solid, so you will be preparing it from a solution the concentration of which you will know or have to determine.


You might look into titrimetry, specifically iodometric titrations...
When I worked on water sterilization methods/technologies, that was how I did my free halogen determination.