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Lab: pH Introduction: The numerical scale called pH indicates how acidic or basi

ID: 863617 • Letter: L

Question

Lab: pH

Introduction: The numerical scale called pH indicates how acidic or basic an aqueous solution is, or whether that solution is neutral. Many environmental processes and environmental engineering applications relay on pH such as coagulation, softening, alkalinity, etc..

Apparatus:

1.100 mL beaker

2. pH meter & probe

3. DI H2O wash bottle & beaker for liquid waste Reagents: Standard buffer solutions pH 4.0, 7.0, 10.0 Procedure:

1. Check to see if pH meter needs to be calibrated by immersing probe about two inches into pH 7.0 buffer solution until reading is complete. If reading falls within 6.95 and 7.05, proceed to next step. If reading is outside that range, calibrate the meter using pH 4, 7, and 10 buffer solutions. (Each meter

Explanation / Answer

answer 3)

The pH of a solution is a measure of the molar concentration of hydrogen ions in the solution and as such is a measure of the acidity or basicity of the solution. The letters pH stand for "power of hydrogen" and the numerical value is defined as the negative base 10 logarithm of the molar concentration of hydrogen ions.

pH = -log10[H+]

The measurement of the pH of a sample can be done by measuring the cell potential of that sample in reference to a standard hydrogen electrode, as in the accepted procedure for measuring standard electrode potentials. This procedure would give a value of zero for a 1 Molar solution of H+ ions, so that defines the zero of the pH scale. The cell potential for any other value of H+ concentration can be obtained with the use of the Nernst equation. For a solution at 25