Unformatted text preview: CaCO 3 solution that will be prepared. After the molarity of the EDTA solution is calculated and standardized, a sample of CaCO 3 with an unknown molar concentration will be obtained and titrated three times with the EDTA solution to the end point color change from wine to blue. The volume of titrant added will be recorded and the molarity of the unknown solution can be calculated form this data. Chemical reactions: Ca 2+ + Y 4----------> CaY 2-K f = [CaY 2-] / [Ca 2+ ][Y 4-] = 10 10.69 Mg 2+ + Y 4----------> MgY 2-K f = [MgY 2-] / [Mg 2+ ][Y 4-] = 10 8.79 Questions and calculations: If you have 25mL of a standard 1 mg/mL CaCO 3 solution how many mLs of the 0.010 M solution do you expect to use in the titration? 25 mL X 1mg/1mL X 1mmol/100mg X 1mol CaCO 3 /1000mmol X 1mol EDTA/1mol CaCO 3 X 1000mL/0.010mol EDTA=25mL of 0.010 mol EDTA solution...
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- Spring '07
- Chemistry, Hard water, magnesium ions