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NaCl is added slowly to a solution that is 0.010 M each in aqueous Cu^+ Ag^+ and

ID: 1052225 • Letter: N

Question

NaCl is added slowly to a solution that is 0.010 M each in aqueous Cu^+ Ag^+ and Au^+ The K_sp's for CuCI, AgCl, and AuCl are 1.9 times 10^-7, 1.8 times 10^-10, and 2.0 times 10^-13 respectively. Which compound will precipitate first? A solution of 30.00 mL of 0.1230 M MCI (aq) is titrated with 0.1750 M NaOH (aq). Calculate the initial pH of the HCI solution What volume of NaOH (aq) will be required to reach the equivalence point? What is the pH of the solution at the equivalence point? What is the pH after addition of 15.50 mL of NaOH solution? What is the pH after addition of 35.70 mL of NaOH solution?

Explanation / Answer

7)

A) Given that 30 mL of 0.125 M HCl

Hence,

[H+] = molarity x volume in Litres = 0.125 M x 0.03 L = 0.00375 mol

pH = -log [H+]

= - log (0.00375)

= 2.42

pH = 2.42

B) At equivalence point,

MHCl VHCl = MNaOH VNaOH

  0.125 M x 30 mL = 0.175 M x VNaOH

  VNaOH = 21.4 mL

Hence,

volume of NaOH required to reach equivalence point = 21.4 mL

C)

pH at  equivalence point = 7.00

Since strong acid (HCl) is titrated with strong base ( NaOH) ,

pH at equivalence point is neutral i.e. 7.