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Calculations with stability (formation) constants

This type of question, asked 2 times: 2021 Paper 19, 2021 Paper 20. All 2 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    2021 Paper 19

    57
    The overall stability constant of the complex ion [Cu(NH3)4]2+\left\lbrack Cu\left( NH_{3} \right)_{4} \right\rbrack^{2 +} is 2.1×10132.1 \times10^{13}. The overall dissociation constant is y×10−14y \times10^{- 14}. Then yy is ____ . (Nearest integer)

  2. Question 2

    2021 Paper 20

    59
    The number of moles of NH3NH_{3}, that must be added to 2 L2\text{ }L of 0.80MAgNO30.80MAgNO_{3} in order to reduce the concentration of Ag+Ag^{+}ions to 5.0×10−8M(Kformation 5.0 \times10^{- 8}M\left( K_{\text{formation~}} \right. for  [Ag(NH3)2]+=1.0×108)\left. \ \left\lbrack Ag\left( NH_{3} \right)_{2} \right\rbrack^{+}= 1.0 \times10^{8} \right) is ____ . (Nearest integer) [Assume no volume change on adding NH3NH_{3} ]