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What Is a Conductometer?

Mal Baxter
Mal Baxter

A conductometer, typically a benchtop or handheld electronics device, is a piece of laboratory equipment also known as a conductivity meter. It measures the electrical conductivity displayed by charged ionic solutions. Attached by cable to a single or asterisk-shaped wand of rods made of different materials, this laboratory equipment essentially detects and measures the rate of transmitted thermal, or heat, energy. This device is often used in experimental and manufacturing applications. Sometimes called a quantitative heat conductometer, it performs in many areas of scientific interest where the changing states of liquids matters.

Temperature probes are sometimes placed at specific points to note minute temperature differences of a liquid solution being measured. These rods consist of an array of materials, such as copper, aluminum, steel, and others. Often featuring a simple control keypad and digital readout, a conductometer transmits an electric field between electrodes; it measures the electromagnetic behavior of charged ions in the liquid. Helping to determine chemical changes and other characteristics, the study of such phenomena is known as conductometry.

Scientist with beakers
Scientist with beakers

Ions are electrically charged particles; put simply, they are atoms or molecules that have gained or lost one or more electrons. This renders their net charges as positive or negative. While an ion can refer to a positive or negative particle, an anion is negatively charged and a cation is positively charged.

An electric charge travels between two electrodes of the conductometer and creates an electric field. The particles begin to migrate in this field according to their charges. Opposites attract; anions travel to the anode, or positively charged electrode. Cations run to the cathode, the negatively charged electrode.

As an aside, the anode and cathode terminals of voltaic cells or storage batteries perform similarly. These, however, are negatively and positively charged, respectively. This might explain a little confusion about these terms.

Sometimes, testing itself can interfere with what it measures; running a consistent electrical current through a solution can alter its composition. To avoid polarizing the substance and creating new layers or other reactions, the conductometer applies an alternating voltage through its electrodes. Analysis of the substance can be conducted with an onboard microprocessor. Occasionally, a cradle supports a labware flask to assist in direct measurements. Alternatively, some benchtop units have a spring-jointed or swivel arm similar to a desktop lamp that allows flexible positioning of the wand over a flask.

Another cylindrical conductometer design allows a self-contained unit to float independently in a solution. Regardless of such design differences, the conductive reading is usually displayed as temperature and range within specified tolerances. One reading is given as a temperature coefficient, which is a kind of numerical constant drawn from a measurement property; other indications can include temperature resolution and accuracy.

Usually, a conductometer can compare specific conductances between different solutions. For example, the conductance of a diluted solution can be compared to a stock solution. This can assist in recognizing factors that change a substance, such as humidity or bacterial growth.

Dissociation, or splitting up of atomic particles, essentially turns liquid into an electrical conductor. This permits studies of resistive capacities, as well as plotting conductance values on a graph to see how conductance corresponds to the concentration of the solution. Such technology helps determine conductivity in any case where the ingredients of liquids have to be examined. It might aid in monitoring bacterial contamination in milk pasteurization processes, to help determine its shelf life, that little sell-by date stamped on milk cartons. Additional uses involve detection of minerals and chemical analyses, the production of semiconductors and printed circuits, as well as pharmaceutical products and many more.

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      Scientist with beakers