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# Activity I.pptx

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# Activity I.pptx

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### Activity I.pptx

1. 1. Activity and Activity Coefficient • In a solution, diferent charged ions (cations and anions) have electrostatic interaction. This interaction in the neutral solutions do not have between inons. • When ions in a solution have high concentrations, cations tend to be surrounded by nearby anions and anions tend to be surrounded by nearby cations. This effect is significant at ion concentrations of 0.01 M and greater.
2. 2. Activity and Activity Coefficient • When ions in a solution have high concentrations, cations tend to be surrounded by nearby anions and anions tend to be surrounded by nearby cations. This effect is significant at ion concentrations of 0.01 M and greater.
3. 3. Activity and Activity Coefficient where Zi denotes the charge on an ion. Ci is related to the formal concentration of each ion. The charge concentration of a solution is describe by the ionic strength, which is calculated from the following expression:
4. 4. Activity and Activity Coefficient
5. 5. Activity and Activity Coefficient Based on these activity coefficients, the equilibrium constants of ideal solutions can be used to determine equilibria in non-ideal solutions. Activity coefficients are unitless numbers that are computed from the Debye- Hückel equation:
6. 6. • Activity coefficients can be computed from the Debye-Hückel equation: Activity and Activity Coefficient
7. 7. Effective hydrated diameters of ions in aqueous solution (25 oC). Cations Anions Rb+, Cs+, NH4 +, Tl+, Ag+ 0.25 K+ Cl-, Br-, I-, NO3 -, HCOO- 0.3 OH-, F-, HS-, ClO4 -, MnO4 - 0.35 Na+ HCO3 -, H2PO4 -, HSO3 -, CH3COO- 0.4-0.45 Hg2 2+ HPO4 2-, SO4 2-, CrO4 2- 0.40 Pb2+ CO3 2-, SO3 2- 0.45 Sr2+, Ba2+, Cd2+, Hg2+ S2- 0.5 Li+, Ca2+, Cu2+, Zn2+ Sn2+, Mn2+, Fe2+, Ni2+, Co2+ Phthalate2-, C6H5COO- 0.6 Mg2+, Be2+ 0.8 H+, Al3+, Cr3+, Fe3+, La3+ 0.9 Activity and Activity Coefficient