Factors Affecting PH Measurement


Factors Affecting PH Measurement

1. Soil Solution Ratio:

Condition being the same, the more water added to the soil sample the higher the soil PH.

2. Salt and Electrolyte Content:

A salt also increases the hydrolysis of Al and Fe ions, increasing the H+ in solution. The salts lower the PH. The use of 0.01 M cacl2 has been recommend as a solution which masks small differences in salt contents without displacing a large fractions of the hydrogen ions.

3. Degree of Dissociations of Hydrogen Ions:

Soil colloids differ in the amounts of discrete hydroxyl groups capable of ionizing the hydrogen ions.

4. Type of the Acidity:

Hydrogen ions adsorbed to electrostatic bands that have great tendency to dissociate than those from the OH groups.

5. CO2 Content:

The CO2 dissolved in water forming H2CO3 lowers the PH markedly.

6. Liquid Junction Potential:

Appreciable liquid junction potential ( Ej) may occur at the liquid junction particularly into very concentrated colloidal electro suspension. Liquid junction potential kept low by the use of a saturated KCL solution.

7. Equipment and Procedure:

Major difference in the PH appears due to inadequate standardization of the equipment rather than a limitation of the equipment.

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