Calculations 1. Determine the molarity of your EDTA solution. Since Zn+ reacts with EDTA in a 1:1 mole ratio the moles of EDTA will be equal to the moles of Zn+. For a solution, moles can be determined by multiplying molarity by volume. mol EDTA = mol Zn+ MEDTAVEDTA MZn2+VZn2+ rearranging the equation above we get: MEDTA MZn2+VZn2+/ VEDTA = 2. Determine an average value and a standard deviation for your EDTA molarity. You can do this on your calculator or use excel. 3. Calculate the value for total water hardness (amount of Ca + Mg). Following convention, this will be reported in terms of CaCO3 in units of mg/L. The moles of hard water is equal to the moles of EDTA used in the titration. Use the equation MEDTA VEDTA= Mhardwater Vhardwater to solve for the molarity of the hard water and then convert the molarity into units of mg/L using the molar mass of CaCO3 which is 100g and the conversion factor 1000 mg = 1.00 g. For the molarity of the EDTA, use your average value as determined in step 2 above. The equation is as follows: Total Hardness = (MEDTA VEDTA/Vhardwater) (100 g CaCO3/mol)(1000 mg/1g) 4. Calculate the magnesium hardness (reported in terms of CaCO3 in units of mg/L, just like the total hardness). Use the equation that follows. magnesium hardness = total hardness(from step 3) - calcium hardness(given by your instructor) 5. Calculate the magnesium concentration (reported in terms of Mg2+ in units of mg/L). Use the equation that follows. Magnesium concentration = (magnesium hardness(from step 4) (24 mg Mg2+/100 mg CaCO3) 6. Determine an average value and standard deviation for your magnesium concentration. 7. Determine your percent error. (Get the actual value from your instructor) Trial 2 Initial Buret Volumre? Final Burut Vorduur) Total Volume 1 11.2 ml 11.2 in 2 11. 2 ml 11 ml 3 11.4 ml 11. 2 ml 0.0ml 0.1 ml 0.2 ml Trial Initial Buret Volumine (Final Buret Volume 1 0.0ml 2.0 ml 2 3 0.0 ml 0.0 ml 2.5ml 3.3ml Total Volume 2.0ml 2.5 ml 2.3 ml