Iodometric Titration of Cu(II) Calculation Preparation of a ~0.0015M KIO3 soluti

Question

Iodometric Titration of Cu(II) Calculation

Preparation of a ~0.0015M KIO3 solution
I weighed out 0.090 g of KIO3 and dissolved it in a 250 mL volumetric flask.

Preparation and standardization of a 0.01M Na2S2O3 solution
I boiled 1 L of distilled water, and cooled it to room temperature. I then weighed
out 2.5 g of Na2S2O3*5H2O in a 1-L volumetric flask, and added 10 mL i-butyl alcohol, fill up
to mark.

I measured out three 10.00 mL aliquots of the KIO3 solution into separate100-mL
Erlenmeyer flasks, and added 0.30 g KI, 30 mL of distilled water, 1 mL 20% (distilled) HCl solution.And then titrate with the thiosulfate solution. I saw the yellow color of the iodine turned to yellowish.After it turned to yellowish, I then added 10 drops of the starch indicator. I then titrate from dark blue into colorless.

Turn from yellow to yellowish:

Trial 1: 11.45 mL

Trial 2: 11.35 ml

Trial 3: 11.05 mL

Iodometric titration of the Cu(II) unknown
I dissolved 1.0 g of unknown in DI water to the mark of a 100 mL volumetric flask.

In 3 different 125 mL Erlenmeyer flasks, I placed 10.00 mL aliquots of my dissolved
unknown above, 40 mL of distilled water, 5 mL 10% acetic acid, and 1 g of KI. I then titrate with the thiosulfate solution from the yellow color of the iodine to yellowish. After it turned to yellowish, I added 10 drops of the starch indicator, and then titrate from dark blue into colorless.

Turn from yellow to yellowish:

Trial 1: 45.5 mL

Trial 2: 44.5 mL

Trial 3: 43.5 mL

Can anyone help me to find the percent mass of Cu in the unknown?

Thanks

Explanation / Answer

I think the answer is a or b

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.