In this worksheet, we will practice describing iodometry, iodimetry, and other redox titration methods and troubleshooting common errors.
Oxalic acid and potassium permanganate react according to the net ionic equation:
Titration of a 20.0 mL aqueous solution of oxalic acid required 23.24 mL of 0.09113 M aqueous potassium permanganate. Calculate to 3 significant figures the concentration of the oxalic acid solution.
A 58.3 mg sample containing is dissolved in 1.0 M . If 23.6 mL of 0.010 M is required to reach the end-point of the titration, what is the mass percent (w/w%) of tin in the original sample?
A 0.357 g sample contains only lead(II) iodide and sodium iodide in 100 mL of distilled water. Titration to the Fajan’s end point requires 22.37 mL of 0.050 M silver nitrate. What is the mass percent (w/w) of lead(II) iodide in the sample?
Triiodide ions are produced by the reaction of iodine with iodide ions. Why should iodine solutions contain an additional iodide salt if used as a titrant?
- ATriiodide ions are more strongly oxidizing than iodine.
- BTriiodide ions are more highly colored than iodine in water.
- CTriiodide ions are more stable than iodine when stored under air.
- DTriiodide salts are more soluble in water than iodine.
- ETriiodide ions undergo a more visible color change during reduction-oxidation reactions.
Which of the following is an accurate description of iodometry?
- AIodine is used as a titrant for an oxidizing analyte.
- BIodine is used as a titrant for a reducing analyte.
- CExcess sodium thiosulfate is reacted with an analyte, and the remainder titrated against iodine.
- DExcess iodide is reacted with an analyte, and the resulting iodine titrated against sodium thiosulfate.
- EExcess analyte is reacted with iodine, and the remained titrated against sodium thiosulfate.
Which of the following would not improve the accuracy of an iodometric titration?
- AAdding starch indicator to the iodine solution.
- BUsing excess iodide in the iodine solution.
- CUsing only fresh iodide solutions.
- DLowering the pH of an acidic analyte solution.
- EUsing only fresh thiosulfate solutions.
Copper(II) nitrate reacts with potassium iodide in water to produce solid copper(I) iodide and elemental iodine:
A copper(II) nitrate solution has a volume of 43.88 mL and concentration of 0.3842 M. Calculate the volume of a 0.2089 M potassium iodide solution needed to convert all of the copper(II) nitrate to copper(I) iodide.
- A 179.4 mL
- B 153.0 mL
- C 175.1 mL
- D 161.4 mL
- E 180.0 mL
Adding aqueous sodium chloride to aqueous silver nitrate results in the precipitation of silver chloride: Calculate the concentration of silver nitrate in a 23.00 mL aqueous sample if 32.10 mL of 0.203 M aqueous sodium chloride is required for the end point to be reached.
- A 0.203 M
- B 0.145 M
- C 0.128 M
- D 0.283 M
- E 0.270 M