pH meter and pH paper-Difference between pH meter and pH paper or Litmus Paper

This page compares pH meter vs pH paper and mentions difference between pH meter and pH paper or Litmus Paper.

pH is mathematical tool to measure acidity of a solution in chemistry. Its value ranges from 0 to 14.
Refer what is pH value and how it is measured >>.

pH meter

pH meter working

• The pH meter is electronic device which is used to measure pH value of liquid. pH indicates acidity ot alkalinity of liquid. It measures concentration of H+ ions in the solution.
•  The figure-1 depicts working of pH meter. As shown it consists of pair of electrodes (glass electrode or measuring electrode and reference electrode) interfaced with meter which can measure smaller voltages usually in milli-volts. It measures the electrical potential produced by the solution whose acidity is to be measured by comparing it with voltage of standard solution. It uses difference in voltage between them to calculate the difference in pH.

pH paper | Litmus Paper

pH paper,Litmus Paper

• The figure-2 depicts pH paper used for pH measurement of a liquid.
• It is dipped in the liquid and kept inside for sometime and removed.
• The change in color of pH paper is verified against the universal pH scale as shown in the figure-3 below.

pH universal scale

• pH paper or hydrion paper is a paper which contains universal indicator as shown.
• Universal Indicator refers to several indicators mixed in order to emit a different color for each pH value.
• pH paper is red in acid solutions and purple in basic solutions.

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