Question

from the class results, did the Ksp change significantly depending on the [K+] concentration firm KCl

Given below is a set of representative data for this lab. This is exactly the sort of date you would have collected in the lab had you done it yourself. Solution # KL HT Volume of Base required (mL) Ave. K K (from KCI) (sum of K from KCl and K from KHT) (same as solubility of KHT) mol/L 26.86 0.000 0.0384 0.0384 0.0015 23.30 0.010 0.049 0.0333 0.0016 20.59 0.020 0.049 0.0294 0.0014 18.36 0.030 0.055 0.0248 0.0014 15.75 0.040 0.063 0.0225 0.0014 1442 0.050 0.071 0.0206 0.0015 12.25 0.060 0.078 0.0175 0.0014 11.14 0.070 0.086 0.0159 0.0014 10.30 0.080 0.095 0.0147 0.0014 9.61 0.090 0.104 0.0137 0.0014 11 8.58 0.100 0.11 0.0123 0.0014 From the class results, how was the molar solubility affected by the change in (K"] concentration from KCI? Explain your answer. From the class results, did the K change significantly depending on the [K] concentration from KCI? Explain your answer.

Answer 1

#7.

Ksp [KHT] = [K+] [HT-]

molar solubility of KHT mol/L , decreases with increasing KCl concentration , as since KCl contributes K+ ions to solution which is common-ion for KHT , thus due to common ion effect molar solubility of KHT decreases with increasing [K+]. ( Common-ion effect describes the suppressing effect on ionization/solubility of an electrolyte/ionic compound when another electrolyte is added that shares a common ion )

[K+] = [K+]KHT + [K+]KCl

thus, Ksp [KHT] = ( [K+]KHT + [K+]KCl } [HT-] , with increasing [K+]KCl , there is decrease in molar solubility of KHT .

#8.

Ksp [KHT] = [K+] [HT-] = ( [K+]KHT + [K+]KCl } [HT-]

It reamins unaffected by KCl conc. in solution as it is product of [K+] and [HT-] ions solubility in solution, thus it is value-neutral property with respect to KCl of KHT solubility in solution.