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The sum of the transport numbers for all of the ions in solution always equals unity: = The concept and measurement of transport number were introduced by Johann Wilhelm Hittorf in the year 1853. [1] Liquid junction potential can arise from ions in a solution having different ion transport numbers.
A metal ion in aqueous solution or aqua ion is a cation, dissolved in water, of chemical formula [M(H 2 O) n] z+.The solvation number, n, determined by a variety of experimental methods is 4 for Li + and Be 2+ and 6 for most elements in periods 3 and 4 of the periodic table.
A smaller ion with stronger hydration, for example, may have a greater Stokes radius than a larger ion with weaker hydration. This is because the smaller ion drags a greater number of water molecules with it as it moves through the solution. [1] Stokes radius is sometimes used synonymously with effective hydrated radius in solution. [2]
When such a bridge is used, the ions in the bridge are present in large excess at the junction and they carry almost the whole of the current across the boundary. The efficiency of KCl/NH 4 NO 3 is connected with the fact that in these salts, the transport numbers [clarification needed] of anions and cations are the same.
The number of solvent molecules surrounding each unit of solute is called the hydration number of the solute. A classic example is when water molecules arrange around a metal ion. If the metal ion is a cation, the electronegative oxygen atom of the water molecule would be attracted electrostatically to the positive charge on the metal ion. The ...
Ion transport through the RO membrane is driven by the gradient of chemical potential within the membrane. The solution-friction model describes this transport by considering the frictions between ions, ions and water, and ions and membrane. The force balance for an ion is given by the equation: [2]
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Between 1853 and 1859 his most important work concerned ion movement caused by electric current. In 1853 Hittorf revealed that some ions traveled more rapidly than others. This observation resulted in the concept of transport number, the fraction of the electric current carried by each ionic species. He measured the changes of the concentration ...