Difference between revisions of "Ionic Strength"
(→Ionic Strength (molal based or m-based)) |
(→Converting from Mole fraction to Molal-based units) |
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Where n is the number of charged species. | Where n is the number of charged species. | ||
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+ | == Converting from Mole fraction to Molal-based units == | ||
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+ | The equation to use is the following: | ||
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+ | [[File:Ionic Strength Conversion-Revised.png]] | ||
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+ | Where: | ||
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+ | I(m) = ionic strength in molal-based units <br> | ||
+ | I(X) = ionic strength in mole fraction-based units<br> | ||
+ | n<sub>LIQUID</sub> = moles of liquid (true species)<br> | ||
+ | n<sub>H<sub>2</sub>O</sub> = moles of water in the liquid phase (true species)<br> | ||
+ | |||
[[user:DMILLER | Author: Diana Miller]] | [[user:DMILLER | Author: Diana Miller]] |
Latest revision as of 12:27, 8 September 2022
Ionic Strength (molal based or m-based)
The ionic strength is a quantity representing the strength of the electric field in a solution, and it is equal to the sum of the molalities of each type of ion present multiplied by the square of their charges, as represented by the following equation:
Where n is the number of charged species.
For example, a 1.0 molar solution of NaCl has 1.0 moles of Na^+ions and 1.0 moles of Cl^- ions in 1 kg of H2O. Therefore, the ionic strength is 1.0 molal.
Now, consider a 1.0 molal solution of CaCl2. This solution has 1.0 moles of Ca^(+2) ions and 2.0 moles of Cl^- ions in 1 kg of H2O. Therefore, the ionic strength is 3.0 molar, or it can be said that a 1.0 molal solution of CaCl2 behaves similar to a 3.0 molar solution of NaCl.
Ionic Strength (mole fraction based or x-based)
In this case the ionic strength is calculated using the mole fraction rather than the molality:
Where n is the number of charged species.
Converting from Mole fraction to Molal-based units
The equation to use is the following:
Where:
I(m) = ionic strength in molal-based units
I(X) = ionic strength in mole fraction-based units
nLIQUID = moles of liquid (true species)
nH2O = moles of water in the liquid phase (true species)