2. A potassium oxalate solution with known concentration is often used to standa
ID: 1028161 • Letter: 2
Question
2. A potassium oxalate solution with known concentration is often used to standardize a potassium permanganate solution. 2a. 1.1270g of potassium oxalate monohydrate (K2C.0 H20, FW- 184.24) are dissolved in 50 mL of deionized water. The resulting solution is quantitatively transferred to a 100 mL volumetric flask and the flask is filled to volume with deionized water. Calculate the molarity of the solution. 2b. 10 mL of the solution are pipetted into a 125 mL Erlenmeyer flask. Calculate the number of moles of oxalate ion, C20A, are present in the flask. 2c. Referring to the equation in Question 1, calculate the number of moles of permanganate ion, MnOs, required to completely react with the oxalate ion in the flask. 2d. The amount of MnO calculated in Question 2c was contained in 23.80 mL of KMn0 solution. Calculate the molarity of the KMn04 solution.Explanation / Answer
2a. Molarity of the solution = Moles of oxalate / volume (L)
Moles of Oxalate = Mass/molar mass
= 1.1270 g/184.24 = 6.1170 X 10 -3 moles
Volume of the solution = 50.0 ml = 50.0 X 10 -3 L
molarity = 6.1170 X 10 -3 moles/50.0 X 10 -3 L = 0.122 M
2b. 10.00 ml of the solution is pietted in to 125 ml erlenmeyer flask. calculate moles of oxalate ion:
Moles of oxalate = molarity*volume = 0.122 moles/L * 10.0 X 10-3 L = 1.22 X 10 -3 moles
2c. For 1 mole of C2O42- you would need 1 moles of MnO4-, so for 1.22 X 10 -3 moles of oxalate you would need
1.22 X 10 -3 moles of MnO4-
2d. Molarity = moles /volume = 1.22 X 10 -3 moles /23.80 X 10 -3 L = 0.0513 M
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