Science Buddies: "Ask an Expert"

We did an experiment to test for water hardness using the soap in the water and shake the jar method where we measured the height of the suds in ml, and then using a commercial water hardness test giving us measurements in parts per million (ppm). Is there any way to compare the results of the two tests? The point of the investigation was to see if the soap suds test is an accurate method of finding water hardness as compared to a commercial test but it seems like its comparing apples and oranges.

Hi! If you know how many liters were in the jar, you may have some luck converting ppm to ml/L. http://www.endmemo.com/sconvert/ppmml_l.php That is a link to a convertor that will do the job for you. 1 ppm = 0.001 ml/l; 1 ml/l = 1000 ppm. Then, if you divide each of your ml measurements by the number of liters in the jar, you will have comparable data.

I hope this helped! Good luck with your project! —Trystan