ph meter

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Analog and Digital pH meter

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Presentation Transcript

pH Meter:

pH Meter

pH:

pH is a unit of measure which describes the degree of acidity or alkalinity (basic) of a solution. It is measured on a scale of 0 to 14. It is defined as the negative logarithm of the hydrogen ion concentration. pH = -log[H+] The pH scale is logarithmic, so a one unit change in pH actually reflects a ten fold change in the acidity or alkalanity. pH

Slide 3:

Litmus Paper Method for Determining pH

Slide 4:

Litmus Paper Litmus paper is useful to determine the pH of a solution when you do not have a pH meter available Proper storage of the litmus paper is essential to maintain quality control

pH value:

The pH value of a substance is directly related to the ratio of the hydrogen ion and hydroxyl ion concentrations. If the H+ concentration is higher than OH- the material is acidic . If the OH- concentration is higher than H+ the material is basic . 7 is neutral, <7 is acidic, >7 is basic pH value

Slide 6:

The pH Scale

Slide 7:

The pH Scale

pH Measurement:

A pH measurement system consists of three parts: a pH measuring electrode, a reference electrode, and a high input impedance meter. The pH measuring electrode is a hydrogen ion sensitive glass bulb. The reference electrode output does not vary with the activity of the hydrogen ion. pH Measurement

The reference electrode supplies a constant value against which we measure the potential of the pH electrode:

The reference electrode supplies a constant value against which we measure the potential of the pH electrode

pH Meter:

A sample is placed in a cup and the glass probe at the end of the retractable arm is placed in it. The probe is connected to the main box. There are two electrodes inside the probe that measure voltage. One is contained in liquid with fixed pH. The other measures the acidity of the sample through the amount of H+ ions. pH Meter

Digital pH meter:

Digital pH meter