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Table 12-1 Activity coefficients for aqueous solutions at 25°C\" Ion size Ionic

ID: 557922 • Letter: T

Question

Table 12-1 Activity coefficients for aqueous solutions at 25°C" Ion size Ionic strength ( M) Ion (, pm) 0.001 0.005 0.01 0.05 0.1 Activity coefficient () 9000.967 0.933 0.914 0.86 0.83 8000.966 0.931 0.912 0.85 0.82 7000.965 0.930 0.909 0.845 0.81 Charge (z) = ±1 CH-CHCH2C0%, (CHJ2CHCH2C0%, (CH,CHJ4N+, (C3H7)2NH3 600 0.965 0.929 0.907 0.835 0.80 500 0.964 0.928 0.904 0.83 0.79 Co(NH3)4(NO2):, CH3C0%, CICH2C0%, (CH3)4N (CH3CH2)2NH2, H2NCH2CO2 H3NCH CO,H, (CH3)3NH+, CH3CH2NH3 OH , F , SCN", OCN , HS , ClO3, CIO4, BrO3, IO4, MnO4, HCO7, H2citrate, CHzNHj, (CH32NHz K, Cl, Br , I, CN, NO2, NO3 Rbf, Cs*, NH, TI, Ag 450 0.964 0.928 0.902 0.82 0.775 400 0.964 0.927 0.901 0.815 0.77 350 0.964 0.926 0.900 0.81 0.76 300 0.964 0.925 0.899 0.805 0.755 250 0.964 0.924 0.898 0.80 0.75 Activity coefficient (Y) 800 0.872 0.755 0.69 0.52 0.45 7000.872 0.755 0.685 0.50 0.425 Charge (z) = ±2 Mg2*, Be2+ Ca2+, Cu2+, Zn2+, Sn2+, Mn2+, Fe2+, Ni2+, Co2+, c,H(CO22 6000.870 0.749 0.675 0.485 0.40:5 Sr*, Ba2+, Cd2+, Hg2+, S2-, S,O2 , woi, H,C(CO2)2 (CH2CO22, (CHOHCO2)2 500 0.868 0.744 0.67 0.465 0.38 Hcitrate 450 0.867 0.742 0.665 0.455 0.37 400 0.867 0.740 0.660 0.445 0.355

Explanation / Answer

How many grams of PbI2 can be dissolved in 1000 mL of a 0.100 M KI solution at 25  oC?

Activity of X = x * [X]

Where:

Activity coefficient () of “x”

[X] = molar concentration concentration of X

Note that Activity coefficient () depends on

Can be found in activity tables as well, with ionic strength of ions from 0.001 0.005 0.01 0.05 0.1

for

Pb+2 = 0.37

I- = 0.755

then

Now,

PbI2(s) = Pb+(aq) + 2I-(aq)

Ksp = Activity of Pb+2 * (Activity of I- ) ^2

Ksp = YPb2+ *[ Pb2+] * (YI- * [I-])

Ksp = 9.8*10^-9

Ksp = YPb2+ *[ Pb2+] * (YI- * [I-])

9.8*10^-9 =(0.37)(S) * (0.755)^2 * (0.1^2)

S = (9.8*10^-9)/((0.37*(0.755^2)*(0.1^2))

S = 0.000004646 M