[ermintrudes_barn]

Hey there, i'm doing a coursework in school on how the hardness of water is affected by boiling it. We are supposed to have three different experiments to add credence to our results. I'm already doing a titration, and measuring the amount of lather produced with soap, but i'm stuck on what else i can do for my third experiment, someone has mentioned colourimetry but i'm unsure as how to go about that and what chemicals, etc i would need to carry that out.
Could someone please possibly suggest what i would need to carry out colourimetry on samples of water and what i would need to compare them with, i'm measuring hardness as the amount of calcium and magnesium present in the samples of water.
Thanks
Sian

[jdurg]

Hmmm.  Could you add some sodium carbonate to the water sample to ppt out calcium and magnesium carbonate?  you could then filter the solution through a pre-weighed coffee filter, let it dry, then weight it to get a quantitative mass of ppt on the filter.

[Tetrahedrite]

I would've said the same thing, add some Na carbonate. For extra points, you can add some sodium sulfate first to produce gypsum (gentle heating helps this to ppte), filter and weigh. Then repeat using sodium carbonate, thus giving you the relative proportions of Mg:Ca in your hard water

[kevins]

Please try to use Calmagite indicator and measure the ABS at 522nm.