A student is tasked with carrying out an oxidation-redaction titration to determ
ID: 509571 • Letter: A
Question
A student is tasked with carrying out an oxidation-redaction titration to determine the amount of hydrogen peroxide. H_2 O_2, in a standard, drug store bottle. The student uses standardized solution of KMnO_4, as the a. Write a balanced half reaction to describe the reduction of MnO_4 (aq) to Mn^3+ (aq) in acidic solution. Write a balanced half-reaction to describe the oxidation of hydrogen peroxide to gaseous oxygen and aqueous H^+ ions in acidic solution. c One of the products of the oxidation-reaction of MnO_4(aq) in basic solution is MnO_4, an insoluble solid. Why should a basic medium be avoided for this titration? d The student prepares a 3% H_2 O_2 solution for titration by adding 10.0 mL of deionized water, 100 mL of 3 M H_2SO_4 and 1.0 mL. of the H_2SO_4 solution to a 250-mL flask. For which of the three species (deionized water H_2SO_4 H_2O_2) mentioned above is knowledge of the exact volume added to the 250-mL flask necessary? Justify your answer. ii. If the student forgets to swirl the flask and rinse the walls of the flask before the endpoint is reached, how might the calculation of the percent H_2 O_2 in the bottle be impacted? Justify your answer. iii. Calculate the volume of 0.02 M MnO_4 (aq) required to completely titrate a 1 mL sample of 3% H_2o_2, the density of which is equal to 1.00 g/mL. e The ion is easily precipitated from solution with alkylammonium cations, polyatomic ions with nitrogen centers. One example, tetrabutylammonium (TBA), forms a stable permanganate salt at room temperature. In contrast, tetramethylammonium (TMA) permanganate is extremely sensitive to shock and highly explosive. The act of scraping it from a glass beaker with a metal spatula can initiate an explosion. The significant difference between the two cations is size. The four methyl groups in TMA are significantly smaller than the four butyl groups in TBA. Use this information to explain why tetramethylammonium permanganate is shock-sensitive and tetrabutylammonium permanganate is stable under normal conditions.Explanation / Answer
(a) MnO4^- + 8H+ + 5e- -------> Mn^2+ + 4H2O
(b) H2O2 -----> O2 + 2H+ + 2e-
(c) Oxidising power of KMnO4 in acidic medium much higher than in basic medium. MnO4^- is not able to oxidise H2O2 is basic medium.
(d) (i) It is necessary to known the exact volume of H2O2.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.