Test+14+-+Total+Water+Hardness

﻿Total Water Hardness

** What is total water hardness? Total water hardness is the sum of calcium and magnesium in the water. When water passes over deposits like limestone the calcium and magnesium can increase and cause the water to be classified as hard water. ** ** The usual exspected levels of calcium hardness in freshwater is in the range of 10 to 250 mg/L. With magnesium the hardness is nearly half the amount of calcium (5 to 125 mg/L). Typical seawater has calcium hardness of 1000 mg/L,and a magnesium hardness of 5630 mg/L, and total hardness of 6630 mg/L. High levels of hard water ions like calcium and magnesium can cause scaly deposits in plumming, appliances, and boilers. ** **Testing Procedure ** 1. Obtain a clean buret and rinse it with a few mL of the 0.0100 M EDTA titrant. Fill the buret a little above the 0-mL level with the EDTA solution. Drain a small amount of the solution so it fills the buret tip and leaves the EDTA solution at the 0-mL mark. Record the buret level on the Data & Calculations sheet, to the nearest 0.01 mL. 2. Prepare the water sample for titration. Use a graduated cylinder to measure 50 mL of your water sample into a 250-mL flask. Add 1 mL of Hardness 1 Buffer Solution to the Erlenmeyer flask using the 1-mL calibrated dropper. Swirl the contents of the flask to mix. Add the contents of one Calmagite 3 powder pillow to the Erlenmeyer flask. Gently swirl the contents of the flask to mix. The solution should now be red in color. 3. Titrate the sample you prepared in Step 2. Slowly add 0.01 M EDTA titrant to the sample in the Erlenmeyer flaskÑstart with1-mL additions. Swirl the sample after each addition of titrant. Near the equivalence point, the red color will start to fade, and become more violet. You should reduce the addition volume to 1 drop at a time.