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    oxalate concentration for calcium oxalate to precipitate

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    7. The Ksp for calcium oxalate (CaC2O4) is 2.7 x 109. If the free Ca+2 concentration were 1mM, what would need to be the oxalate concentration for calcium oxalate to precipitate?

    8. What would be the voltage of a Zn|Zn+2||Cu+2|Cu cell, once the concentration of Zn+2 went to 1.5M and the CU+2 concentration diminished to 0.5M?

    © BrainMass Inc. brainmass.com December 24, 2021, 6:43 pm ad1c9bdddf
    https://brainmass.com/chemistry/oxidation-reduction-and-electrochemistry/oxalate-concentration-calcium-oxalate-precipitate-133459

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    7. The Ksp for calcium oxalate (CaC2O4) is 2.7 x 109. If the free Ca+2 concentration were 1mM, what would need to be the oxalate concentration for calcium oxalate to precipitate?
    CaC2O4¬ -- Ca2+ + (C2O4)2-
    If the reaction quotient is greater than the Ksp, precipitation occurs.

    We know the concentration of Ca2+ is 1 mM = 0.001 M, so

    So the oxalate concentration needs to be greater than for calcium oxalate to precipitate.
    I believe the Ksp should be 2.7 x 10-9 since calcium oxalate is only soluble.

    8. What would be the voltage of a Zn│Zn+2║Cu+2│Cu cell, once the concentration of Zn+2 went to 1.5M and the CU+2 concentration diminished to 0.5M?
    The voltage of any electrochemical cell is a function of the molar concentrations of the compounds involved in the cell, as described by the Nernst equation:
    aA(s) + bB+(aq) ---> cC(s) + dD+(aq)
    Ecell = E° - (0.06/n) log {[D+]d/[B+]b}

    For Zn│Zn2+║Cu2+│Cu cell,
    Zn(s) + Cu2+(aq) ---> Cu(s) + Zn2+(aq)
    n = 2, then the voltage equation becomes

    Now we need to figure out E0, which is the standard electrode potential.
    Cu2+(aq) + 2e- ---> Cu(s) E° reduction = +0.34 V
    Zn(s) ---> Zn2+(aq) + 2e- E° oxidation = -0.76 V
    So
    Now we know the two ion concentrations,

    So voltage of the cell is 1.0857 V with the given concentrations.

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    © BrainMass Inc. brainmass.com December 24, 2021, 6:43 pm ad1c9bdddf>
    https://brainmass.com/chemistry/oxidation-reduction-and-electrochemistry/oxalate-concentration-calcium-oxalate-precipitate-133459

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