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A 200 mg sample of pure calcium carbonate was acidified and dissolved in 500 ml of solution. a 50 ml sample required 25 ml of an EDTA solution for titration. find the molarity of the EDTA solution
Accepted Answer
Calculate the number of moles of EDTA used in the titration
EDTA is a hexadentate ligand, meaning it can bind to a metal ion using six donor atoms.
In this case, we assume that EDTA binds to calcium ions in a 1:1 ratio.
Therefore, the number of moles of EDTA used in the titration is equal to the number of moles of calcium ions present in the 50 mL sample.
Convert the mass of calcium carbonate to moles of calcium ions
The molar mass of calcium carbonate is 100.09 g/mol.
Therefore, the number of moles of calcium carbonate in the 200 mg sample is:
200 mg / 100.09 g/mol = 0.002 mol
Since calcium carbonate dissociates into one calcium ion and one carbonate ion, the number of moles of calcium ions present in the 200 mg sample is also 0.002 mol.
Calculate the molarity of the EDTA solution
The volume of the EDTA solution used in the titration is 25 mL.
Therefore, the molarity of the EDTA solution is:
0.002 mol / 0.025 L = 0.08 M
Therefore, the molarity of the EDTA solution is 0.08 M.
EDTA is a hexadentate ligand, meaning it can bind to a metal ion using six donor atoms.
In this case, we assume that EDTA binds to calcium ions in a 1:1 ratio.
Therefore, the number of moles of EDTA used in the titration is equal to the number of moles of calcium ions present in the 50 mL sample.
Convert the mass of calcium carbonate to moles of calcium ions
The molar mass of calcium carbonate is 100.09 g/mol.
Therefore, the number of moles of calcium carbonate in the 200 mg sample is:
200 mg / 100.09 g/mol = 0.002 mol
Since calcium carbonate dissociates into one calcium ion and one carbonate ion, the number of moles of calcium ions present in the 200 mg sample is also 0.002 mol.
Calculate the molarity of the EDTA solution
The volume of the EDTA solution used in the titration is 25 mL.
Therefore, the molarity of the EDTA solution is:
0.002 mol / 0.025 L = 0.08 M
Therefore, the molarity of the EDTA solution is 0.08 M.
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