2 MnO_2^2- + 5C_2O_4^2- + 16H^+ rightarrow Mn^2+ + 5 CO_2 + 8H_2O What is the ox

Question

2 MnO_2^2- + 5C_2O_4^2- + 16H^+ rightarrow Mn^2+ + 5 CO_2 + 8H_2O What is the oxidizing agent in the balanced net ionic equation above? What is the reducing agent? Which is oxidized? Which element is reduced If 32.24 mL of a 0.0185 M KMnO_4 solution were required to titrate the iron in a 0.989 g of unknown iron sample. Calculate the percent iron in the sample. Indicate what error(small, large, or none) is Introduced into the percent iron in the unknown and explain briefly why in each case If the permanganate solution contains some contaminant. If H_2SO_4 is not added to the solution. If some iron unknown is spilled after weighing, but before titrating with KMnO_4. Using the Internet, find the MSDS for phosphoric acid, sulfuric acid and potassium permanganate. Write in table form the chemical name, formula, MW, density, hazard and any other cautionary information. What is the importance of redox reactions in biological systems?

Explanation / Answer

Ans:-

1.  2MnO4- (aq) + 16H+ (aq) + 5C2O42- (aq) --> 2Mn2+ (aq) + 8H2O (l) + 10CO2 (g)

MnO4- (the oxidizer, it takes electrons)
H+ (combines with MnO4 - oxygen to make water)
C2O42- (the reducer, it loses electrons)
Mn2+ (the reduced form of manganese formed by MnO4- taking electrons)
H2O (molecule formed with MnO4- oxygen)
CO2 (molecule formed with the oxidized form of carbon after oxalate lost electrons

2. Given that 32.42 ml of a 0.0185M KMnO4 solution required for 0.989gm of the Fe containing sample

Therefore % of Fe in the sample can be calculated as follow:-

Mno4- + 8H+ + 5Fe ------>Mn2+ + 5Fe3+ + 4H2O

158.034 X 0.0185 X32.24/1000 = 5 x 55.845 x 0.0185 X32.24/1000

0.094258 gm of KMnO4 = 0.166541 Fe

0.166541/0.989 x100 = 16.83933%

So the % of Fe in the sample is 16.84 %

3. As the basic equation of the redox reaction is Mno4- + 8H+ + 5Fe ------>Mn2+ + 5Fe3+ + 4H2O

a. In case of any contamination in KMnO4 solution it will give wrong results.

b. The redox reaction is carried out in the presence of acid H2SO4, in case the acid is not used the reaction will not proceed as considered and MnO4- will get reduced in different manner.

c. Any change in weight of the sample will give wrong results.

4. The cellular respiration in the biological process involves oxidation of organic compounds to release energy. Thus redox reaction is base for an oxidation-reduction reaction in biological system.

0.166541/0.989 x100 = 16.83933%

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