Hard water is formed when water passes through or over limestone or chalk areas and calcium and magnesium ions dissolve into the water.
The hardness is made up of two parts: temporary (carbonate) and permanent (non-carbonate) hardness. When water is boiled, calcium carbonate scale can form, which can deposit on things like kettle elements. The scale will not stick to kettles that have a plastic polypropylene lining but will float on the surface. The permanent hardness that comprises calcium and magnesium sulphate does not go on to form scale when heated or boiled. concept of complexometry is a form of volumetric analysis in which the formation of a colored complex is used to indicate the end point of a titration. Complexometric titrations are particularly useful for the determination of a mixture of…show more content… A 25.00 mL aliquot (a portion or part) of the standard calcium solution reacts with 27.25 mL of the EDTA solution. What is the molarity of the EDTA? 3. Ca2+ concentration in an unknown solution CaCO3 reported as ppm CaCO3.
A 50.00 mL unknown solution requires 25.55 ml of the standardized EDTA solution for complete reaction. What is the Ca2+ concentration in the unknown reported as ppm CaCO3 ? Calculations
1. To determine the titrant volumes used, subtract the initial volume from the final volume for each trial. Record the titrant volumes for the two trials on the Data & Calculations sheet.
Important: If the titrant volumes for the two trials are not in close agreement, you should repeat Steps 1–3 of the Testing Procedure until you have two trials that are close.
2. Calculate the value of total water hardness.
a. For each trial, determine total water hardness using the equation total water hardness as CaCO3 (mg/L) = (titrant volume) ✕ 20.0
b. Record the total water hardness value on the Data & Calculations sheet.
3. Calculate magnesium hardness (mg/L as CaCO3) and magnesium concentration (mg/L