1. In this experiment you titrated three separate samples of a known mass of zin
ID: 902417 • Letter: 1
Question
1. In this experiment you titrated three separate samples of a known mass of zinc chloride which had been dissolved in a known total volume. Explain why this was a better approach to determining the small, whole number ratio of moles zn to moles cl than titrating three separate mass samples of zinc chloride, each dissolved to a total volume of 25.00 mL.
Assume that before weighing out the sample, the zinc chloride used had absorbed atmospheric water.
a). Would the number of moles and mass of Zn determined to be in the titrated sample of zinc chloride be: greater than true/less than true/ or true? explain
b). Would the mass of Cl in the titreated sample be greater than true/less than true/true? explain
Explanation / Answer
(a)There wuld be no effect on the number of moles and mass of Zn determined, because while calculating the mass of Zn we donot use the mass of ZaCl2 as
mg of Zn = M(EDTA) x V(EDTA, mL)x molar mass of Zn x 10
(b) Since we calculate the mass of chlorine by subtracting the mass of ZnCl2 from the calculated mass of Zn, the mass of chlorine calculated will be greater than the actual value.
1) If we take separate mass of ZnCl2 and dissolve each in a total volume of 25.0 mL, then the mass of ZnCl2 calculated in each sample may be different creating less accuracy in calculation than dissolving a known mass in a known total volume.
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