Learn how to make potassium chloride solution for calibration of conductivity meter which is needed in many applications such as research, practical, pharmaceutical, chemical laboratory, industries, etc.
The conductivity meter is a very significant tool in several applications for measuring conductance, it measures the level of conductivity in solutions. To provide reliable readings, the conductivity cell must be in proper working condition.
A few factors that could shorten the lifespan of the conductivity cell include sample composition, temperature, and how the conductivity cell is stored and maintained. Care and preservation of conductivity cells ensure not just a longer lifespan but also more precise readings.
Requirements of glassware, chemicals, and apparatus:
Digital balance, beaker, pipette, pipette bulb, volumetric flask, measuring cylinder, glass rod, funnel, distilled water, AR/LR grade potassium chloride (KCl), etc.
How to prepare calibration solution for conductivity meter:
Calculation method:
Molar mass KCl = 39.1+35.45 = 74.55 g/mol,
Mol KCl needed to make 100 mL of 0.01 M solution:
mol = 100 mL / 1000 mL/L x 0.1 mol /L = 0.01 mol KCl
Mass KCl required = 0.01 mol * 74.55 g/mol = 0.7456 g KCl
Therefore, to make a standard KCl solution for conductivity (0.01 M KCl, 1411 μS at 25°C), weigh accurately 0.7456 gm of potassium chloride and dissolve it in 500 ml of distilled water in a volumetric flask. Once it has completely dissolved, make up the volume to 01 liter with distilled water, and properly mix it.
The standard value of conductance at coefficient-1.92, K=cell constant:
|
Molarity/Concentration of KCl |
Standard conductivity |
|
0.001 M |
147 µS/cm ±10% at 25°C |
|
0.01 M |
1.413 mS/cm ±10% at 25°C |
|
0.1 M |
12.88 mS/cm ±10% at 25°C |
Why do we use KCl for calibration of the conductivity meter?
The conductivity meter should be frequently calibrated using pre-prepared standard solutions to get accurate and reproducible results. Potassium chloride (KCl) is the most common solution to perform the calibration of the conductivity meter because it is soluble and very stable.
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