2a) Moles of Na2EDTA.2H2O = (volume of Na2EDTA.2H2O in L)*(concentration of Na2EDTA.2H2O) = (0.635 mL)*(1 L/1000 mL)*(0.0100 M) = 6.35*10-6 mole (ans).
b) Write the balanced chemical equation for the reaction between Ca2+ ions and Na2EDTA.2H2O as below.
Ca2+ (aq) + Na2EDTA.2H2O (aq) ---------> CaEDTA (aq) + 2 Na+ (aq) + 2 H2O (l)
As per the stoichiometric equation,
1 mole Na2EDTA.2H2O = 1 mole Ca2+.
Therefore, mole(s) of Ca2+ reacted = 6.35*10-6 mole (ans).
3) We took 5.00 mL of tap water and the tap water contained 6.35*10-6 mole Ca2+ ions. Therefore, concentration of Ca2+ in the tap water = (moles of Ca2+)/(volume of solution in L) = (6.35*10-6 mole)/[(5.00 mL)*(1 L/1000 mL)] = 1.27*10-3 mol/L = 1.27*10-3 M (ans).
PRE-LABORATORY QUESTIONS, WATER: DETERMINING THE CONCENTRATION OF CALCIUM IONS IN WATER SAMPLES EXPT. SA HARD Prior...
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