Assignment 1 CVEN9887 Value: 10% Total Marks: 100 Due date: 15th of June 11:00 Hand in via electronic hand-in box in Moodle The following describes a simplified soil system where CO2 from vegetation respiration and bacterial respiration in soil is dissolved in the soil pore water to produce a dissolved soil water [CO2]T = 1ꞏ10-2 M. The system is assumed to have reached equilibrium at standard state (P = 1 atm, T = 25 °C). So the recipe is [CO2]T = 1ꞏ10-2 M and pure water. The species in the system are therefore: (H2O), H+, OH-, H2CO3*, HCO3-, CO32- (a) write the reaction equations relevant for water and the carbonate system describing the system. Make sure that the equilibrium constants are consistent (i.e. at standard state). (b) Construct a tableau for the system. (c) Write all the mole balance equations (satisfying the tableau) and the mass law equations for the problem as defined by the tableau. (d) Verify that the mole balance equations satisfy the condition of electro-neutrality (charge balance). (e) Sketch a graphical solution in a log C vs. pH diagram. (f) Using the mole balance and mass law equations defined by the Tableau to derive an algebraic solution. Justifiable approximations should be used. Calculate pH and the concentration of all species. (g) Calculate an updated value of the dominant carbonate specie. Use the calculated concentration of all carbonate species calculated in question (f) above and use the mole balance equation for total carbonate. Important: Verify the validity of all your assumptions! (such as omitting species from mole balance equations by assuming low concentrations). End of the assignment














































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