[toshiba]

Hi, first post here, nice to meet you all. If this is posted in the wrong section, please feel free to move it as required.

Anyways, Im doing this activity about arsenic and how its causing diseases, cancers, and such when people drink water with arsenic in it. So, what I have to do is find a way to reduce the amount of arsenic. Since we are in a classroom, we used sodium phophate instead of arsenic. So, what we did was take that sodium phosphate, made a 250 mL solution with a concentration of 0.15 mole/L with distilled water. Ok so far, so good. Now comes the hard part....

We were provided with several other chemicals including iron (iii) phosphate, iron (iii) sulphate, iron chloride and ferric something. What we had to do was mix a certain amount of our sodium solution, with a certain amount of each of these chemicals, and then form a precipitate. We then have to weight out the solid or something, and compare which chemical had the greatest amount of sodium phosphate, or in other words lower the amount of sodium phosphate....i have no idea at all. i do not even know if that is what we are supposed to do. Does anyone recognize this method??? How do I know how much of each chemical i use??? I can provide other details, just dont know which ones so please ask and I may know.

Thanks for taking the time to read this, and I hope you guys can guide me through on what to do.

[toshiba]

I'm not much interested in the numbers, but more on what I have to do. I balanced an equation and found that I need to add about 1.47 g of Ferric sulphate (thats one one) to our sodium phosphate solution. The reason why I could do this was because I was dealing with ferric sulphate, which is a solid, thus I was dealing with mass in grams. Now, with the liquids I pretty much did the same thing and found out how much I needed to add into our solution. How would you figure out the amount of precipitate that would form after the reaction???