pH -> alkalinity in ppm

[deleted-322471]

Hi there!

For a project of mine I need the alkalinity of water in ppm. I didn't think it to be too hard but when I needed to do the actual calculation my brain just stopped and now I pretty much stuck.

What I got is this:
A pH of 5.

That's it. I know alkalinity can be calculated using the pOH (which in this case would be 9) and I know it isn't that hard of a calculation but I am just stuck

Please help?

[deleted-291782]

Hello and thank you for your question,

The measurement of pH and alkalinity can be correlated, but you cannot derive it just by knowing the pH. The pH of a solution is indicative of how strong an acid is (related to the concentration of H+ ions in solution), while the alkalinity is a measure of water's buffering capacity (the concentration of ions that resist pH changes, such as carbonate ions).

In order to measure the alkalinity, you can do a titration experiment in a lab that ultimately allows you to express alkalinity in terms of CaCO3 in mg/L, which can be converted to ppm. See the website below, it gives some helpful information on alkalinity and pH:

http://dnr.wi.gov/regulations/labcert/d ... enchem.pdf

Let us know if you will have to do further experiments (such as the titration experiment above), and we can help you on the setup.

Best of luck!