# Difference between revisions of "Ionic Strength"

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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: | 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: | ||

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Where n is the number of charged species. | Where n is the number of charged species. | ||

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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. | 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. | ||

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=Ionic Strength (mole fraction based or x-based)= | =Ionic Strength (mole fraction based or x-based)= | ||

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In this case the ionic strength is calculated using the mole fraction rather than the molality: | In this case the ionic strength is calculated using the mole fraction rather than the molality: | ||

− | + | [[File:mass fraction based.png]] | |

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Where n is the number of charged species. | Where n is the number of charged species. |

## Revision as of 20:36, 13 February 2020

# 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.