Systematic Treatment of Equilibrium: In this Question #2 you are going to employ

Question

Systematic Treatment of Equilibrium: In this Question #2 you are going to employ the systematic treatment of equilibrium to determine the equilibrium concentrations of all species in a solution – specifically in an ion chromatography mobile phase solution. When you perform ion chromatography (IC) in the CHEM326 laboratory, you utilized a mobile phase constructed by adding 1.4x10-3 moles of NaHCO3 (sodium bicarbonate, pKA2 = 10.3), 4.5x10-3 moles of Na2CO3 (sodium carbonate, pKB = 3.7) to a volumetric flask and filling to the 1.0 L mark with nanopure H2O. For this question assume all activity coefficients are equal to 1.0 and that there is no CO2 in the system from the atmosphere (there will be some from the carbonate added, but no exchange with the atmosphere); i.e. we are assuming the nanopure water used for the mobile phase is initially carbonate free and is never exposed to the atmosphere.

Help:

H2CO3 (carbonic acid) has a pKA1 = 6.3 (for dissociation of the first proton)

CO2(aq) + H2O(l) <-> H2CO3(aq) K = 1.70x10-3

While we may write the chemical formula for sodium carbonate as Na2CO3 and sodium bicarbonate as NaHCO3 – in solution these ionic compounds should be assumed to be 100% dissociated into Na+, HCO3 - , and CO3 2- ions.

System is at room temperature (298 K) and 1 atm. pressure

a. How many different chemical species are present in this solution at equilibrium? List every chemical species found in this solution at equilibrium.

b. As part of the systematic treatment of equilibrium, you must produce as many linearly independent equations as unknown variables in the system. List all of the equations necessary to determine the equilibrium concentrations of all of the chemical species in the solution at equilibrium. You do not have to re-arrange your algebraic equations into a form conducive for plugging them input into a numerical solver (Python) – e.g. you can just provide the equilibrium, charge balance, and material balance expressions in their native form.

c. For the material balance equation you constructed in Part B for the carbonate species in the system – report the formal concentration that you are going to utilize for this systematic treatment of equilibrium.

d. For the material balance equation you constructed in Part B for the Na+ species in the system – report the formal concentration that you are going to utilize for this systematic treatment of equilibrium.

e. Implement the systematic treatment of equilibrium in Python and compute the pH, CO2(aq) concentration, and HCO3 - (bicarbonate) concentration in the solution at equilibrium. Report the pH to 1 decimal place and the other two concentrations with 2 significant digits. i. Equilibrium pH:_______________ ii. Equilibrium [CO2]aq: ____________________ iii. Equilibrium [HCO3 - ]:____________________

Explanation / Answer

When equilibrium is achevied that means conc. Of reactants and products on both side is equal .if we distrub the equilibrium by applying conc. Temp. Pressure. That equilibrium is distrub and shift that means forward and backwards according to situation.

And pH is the negative logarithmic of hydrogen ion conc

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