Difference between revisions of "Ionic Strength"

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(Created page with "=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 mo...")
 
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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:
  
I=1/2 ∑_(i=1)^n▒〖(z_i^2 m_i)〗
+
[[File: ionic molal based.png ]]
  
 
Where n is the number of charged species.
 
Where n is the number of charged species.
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I=1/2((z_(Na^+ ) )^2 (m_(Na^+ ) )+(z_(Cl^- ) )^2 (m_(Cl^- ))
+
[[File:molal based.png]]
 
+
I=1/2((1)^2 (1)+(-1)^2 (1)=1
+
  
  
 
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.
  
 
+
[[File:numbers molal based]]
I=1/2((z_(Ca^+ ) )^2 (m_(Ca^+ ) )+(z_(Cl^- ) )^2 (m_(Cl^- ))
+
 
+
I=1/2((2)^2 (1)+(-1)^2 (2)=3
+
 
+
  
 
=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]]
I=1/2 ∑_(i=1)^n▒〖(z_i^2 x_i)〗
+
  
  
 
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:

Ionic molal based.png

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.


Molal based.png


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.

File:Numbers molal based

Ionic Strength (mole fraction based or x-based)

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

Mass fraction based.png


Where n is the number of charged species.