# E6: Activity Coefficients at 25°C

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occonline.occ.cccd.edu/online...nt%20Table.pdf

Ion Effective Radius $$R_x$$ Activity Coefficients at Ionic Strengths
0.001 0.005 0.01 0.05 0.1
H3O+ 900 pm 0.967 0.933 0.914 0.86 0.83
Li+ , C6H5COO‐ 600 pm 0.9 0.929 0.907 0.84 0.80
Na+ , IO3 ‐ , HSO3 ‐ , HCO3 ‐ , H2PO4 ‐ , H2AsO4 ‐ , C2H3O2 ‐ 4 400‐450 pm 0.964 0.928 0.902 0.82 0.78
OH‐ , F ‐ , SCN‐ , HS‐ , ClO3 ‐ , BrO3 ‐ , IO4 ‐ , MnO4 ‐ 350 pm 0.964 0.926 0.900 0.81 0.76
K+ , Cl‐ , Br‐ , I ‐ , CN‐ , NO2 ‐ , NO3 ‐ , HCOO‐ 300 pm 0.964 0.925 0.899 0.80 0.76
Rb+ , Cs+ , Tl+ , Ag+ , NH4 + 250 pm 0.964 0.924 0.898 0.80 0.75
Mg2+, Be2+ 800 pm 0.872 0.755 0.690 0.52 0.45
Ca2+, Cu2+, Zn2+, Sn2+, Mn2+, Fe2+, Ni2+, Co2+ 600 pm 0.870 0.749 0.675 0.48 0.40
phthalate2‐ 600 pm 0.870 0.749 0.675 0.48 0.40
Sr2+, Ba2+, Cd2+, Hg2+, S 2‐ 500 pm 0.868 0.744 0.670 0.46 0.38
Pb2+, CO3 2‐ , SO3 2‐ , C2O4 2 450 pm 0.868 0.742 0.665 0.46 0.37
Hg2 2+, SO4 2‐ , S2O3 2‐ , CrO4 2‐ , HPO4 2‐ 400 pm 0.867 0.740 0.660 0.44 0.36
Al3+, Fe3+, Cr3+, La3+, Ce3+ 900 pm 0.738 0.540 0.440 0.24 0.18
PO4 3‐ , [Fe(CN)6] 3‐ 400 pm 0.725 0.500 0.400 0.16 0.095
Th4+, Zr4+, Ce4+, Sn4+ 1100 pm 0.588 0.350 0.255 0.10 0.065
[Fe(CN)6] 4‐ 500 pm 0.570 0.310 0.200 0.048 0.021

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