Question

(10 pts.) (5 pts. (5 pts.) 3. Soils in the rice paddies of Mekong delta have been continuously submerged and used for growing rice. These soils developed on pyrite (FeS.)-rich former marine deposits. During this process, SO and Fes are being released into the environment. Answer the following questions: (a) Assuming that the oxidation state for Sin Fes, is -1, write the balanced half reactions for Fe and S. (b) Write the complete redox reaction for this system. (c) Using information from the final redox reaction for this system, comment on how the pH of this system is affected. 4. Microorganisms play an important role in mediating chemical reactions that are thermody namically favored. Consider the following reaction: NO; + H2O + 2H - NH; +20, (a) Write N and O balanced half reactions that lead to the above redox reaction (b) Is this reaction thermodynamically favored? (Hint: Calculate A.G.) (10 pts.) (10 pts.)

Answer 1

* Answer 2 -2 3) a Balanced half Reactions for Fe and S. For Fe (Half) Fet2 - Fets te For s (Half) 5² + 8 H2O 2500 + 16 Ht + 146 b) Complete Redox Reaction for the System 4 FeS₂ + 1502 + 2H2O 2 Fe₂(SO4)3 + 2H₂50u humid or moist Conditions, sedimentary aerobic sulphide minerals can oxidise Chemically, but it is a Slow process. Various micro-organism are adaptea to onidise Sulphides either directly through sulphur transformatians or by facilitating (catalysing) such rate-limiting Reactians. The following following Oridation equation Reaction pyrite describe Reaction Equation and formation of sulphuric acid that causes Soil PH to Reduce below 4 FeS₂ +1502 + 2H20 - 02 Fe2(SO4)₂ + 2 H2504 c) Under humid or moist a