The following assumptions are valid for this exam unless stated otherwise:

• A temperature of 25°C.
• Volumes are additive.
• Monoprotic acid assumptions for polyprotic acids can be used where appropriate.  These assumptions do not need to be checked unless it is requested in the question.

Calculate the solubility of CuS in a solution that is 1.00 x 10 ^–3 M in NH ₃ .  You may neglect any acid-base effects and assume that the concentration of ammonia remains constant at the value stated in the problem.

For Cu ²⁺ and NH ₃ :

b ₁ = 1.00 x 10 ⁴

b ₂ = 3.16 x 10 ⁷

b ₃ =  2.00 x 10 ¹⁰

b ₄ =  6.31 x 10 ¹¹

Write a mass balance for ammonia for the solution described in the problem previous.  Include species that might result from acid-base equilibria in the solution.

  

Write the charge balance for the solution described in the problem. Include species that might result from acid-base equilibria in the solution.