How to test electrical conductivity of a solution

how to test electrical conductivity of a solution

Conductivity of Acids and Bases

Place about g of solid calcium carbonate (CaCO 3 into a small, clean beaker and test the conductivity. Add 5 mL distilled water to the calcium carbonate; test the conductivity of the solution. Dispose this solution in the sink and rinse the beaker. Use 5 mL of each of the following in mL beaker to test the conductivities. Oct 31, We may measure the electrical conductivity of a liquid solution by passing an electric current through it. The most primitive form of conductivity sensor (sometimes referred to as a conductivity cell) consists of two metal electrodes inserted in the solution, connected to a circuit designed to measure conductance (\(G\)), the reciprocal of resistance (\(1 \over R\)):Author: Tony R. Kuphaldt.

Electrical conductivity is based on the flow of electrons. Metals are good conductors of electricity because they allow electrons to flow through the entire piece of material. In comparison, distilled water is a very poor conductor of electricity since very little electricity flows through water.

Highly ionized substances are strong electrolytes. Strong acids and salts are strong electrolytes because they completely ionize dissociate or separate in solution. The ions carry the electric charge through the solution thus creating an electric current. The current, if sufficient enough, will light one or both LEDs on a conductivity metershown at right. Slightly ionized substances are weak electrolytes. Weak acids and bases would be categorized as weak electrolytes because they do not completely dissociate in solution.

Substances that do not conduct an electric current are called non-electrolytes. Non-electrolytes do not ionize; they do not contain moveable ions.

The LEDs of a conductivity meter will not light because there are no ions to carry the electric current. The table below lists examples of strong, weak and non-electrolytes. Solutions: acetic acid, aluminum nitrate, ammonium hydroxide, calcium hydroxide, citric acid, ethanol, hydrochloric acid, magnesium hydroxide, magnesium sulfate, nitric acid, potassium iodide, sodium chloride, sodium hydroxide, sucrose. Be cautious with hydrochloric acid, nitric acid, sulfuric acid and concentrated acetic acid.

Although low in concentration, what is gestalt therapy explained simply individuals may have extreme skin sensitivities. If you experience any tingling sensations or skin discolorations, rinse immediately with large amounts of water for 15 minutes.

Inform your instructor ASAP. Only the copper electrodes should be rinsed with water. Switch the meter on and dip the copper electrodes to test conductivity. Thoroughly rinse with distilled water after each test, and dry with Kimwipes. Switch the meter off between uses. How to get rid of gingivitis in a day sure to rinse and dry the electrodes between tests, using your wash bottle with waste beaker, and Kimwipes.

Dispose the solution and rinse the beaker in the sink between tests. Dispose the waste beaker solution in non-hazardous waste in the hood. Write each compound as it exists in aqueous solution e. Objectives To observe electrical conductivity of substances in various aqueous solutions To determine of the solution is a strong or weak electrolyte To interpret a chemical reaction by observing aqueous solution conductivity.

Dry using a Kimwipe tissue. When switched on, the lights should not be lit any color. If they are, repeat the rinsing and drying. Note Switch the meter on and dip the copper electrodes to test conductivity.

Why is distilled water a weaker conductor than tap water? Classify each of the following as non-ionized, partially-ionized, or ionized. Hydrochloric acid. Hydrobromic acid. Hydroiodic acid.

Nitric acid. Sulfuric acid. Perchloric acid. Chloric acid. Sodium hydroxide. Potassium hydroxide. Calcium hydroxide. Barium hydroxide. Sodium chloride. Potassium carbonate. Copper II sulfate. Acetic acid. Carbonic acid. Citric acid. Phosphoric acid. Ammonium hydroxide. Magnesium hydroxide. Silver chloride. Calcium carbonate. Barium sulfate. Distilled water.


Apr 24, As long as the solution is unsaturated, the salt will completely dissociate into sodium and chlorine atoms. To measure the conductivity you can use a conductivity meter. Wash thoroughly the mL beaker and electrodes with distilled (deionized) water. Your measurements will be erroneous if these are not completely clean. Nov 18, We look at the electrical conductivity of several solutions. Substances include tap water, distilled water, sodium chloride, hydrochloric acid, sodium hydrox. 1. Rinse conductivity cell with three portions of KCl, M 2. Immerse in the standard KCl solution 3. Adjust temperature compensation dial to / C 4. Adjust meter to read mho/cm EC meter without built-in temperature compensation 1. Rinse conductivity cell with three portions of KCl 2. Note the temperature of fourth portion Size: KB.

Remember me This feature requires cookies to be enabled. William DeBoer gives us a quick chemistry lesson. Electrical conductivity test EC is a quick and inexpensive way to determine the salt concentration of a solution. For growers, it provides a reliable method of nutrient monitoring.

But what exactly is EC? How does temperature affect it? How does fertilizer application correlate to EC values? And why does EC even matter to a grower? To answer these questions, first we must discuss four things:. An electrical current measured in amperes is the movement of electrons over time across a medium such as water.

Put simply, EC gauges how a current moves in solution. An EC probe is comprised of two electrodes to which voltage is applied. The instrument calculates the reciprocal of this value, allowing electrical conductivity to be calculated. The resistance is calculated based on the distance between the two electrodes.

The relationship between temperature and EC is direct, in that with a one degree Celsius increase Most EC probes that also measure temperature should have a built-in adjustment so that no correction is necessaryif in doubt, be sure to check the specifications of the EC probe. Next, the elements and compounds that act as electrical conductorsionsand the action of ionization will be examined. An ion is an element that has gained or lost an electron. This gain or loss of electrons occurs because water breaks the ionic bond of certain compounds in a process known as ionization.

For example, let us examine a compound such as magnesium chloride MgCl2. Since these are charged ions, they are now able to act as electrical conductors and will contribute to electrical conductivity.

What is important about this chemical process for growers to understand is the relationship between EC and fertilizers. Synthetic fertilizers are made from among other things soluble salts of nitrates or ammonia , phosphates , potassium , calcium , magnesium or sulfates.

Organic fertilizers are not high in salts and will often have a very low EC, so proper nutrient monitoring using standard guidelines is problematic. This will be an important consideration when attempting to mix appropriate fertilizer solutions for plants that will account for the ions in the water.

An EC reading will provide not only a measurement of the fertilizer content prior to incorporation with the plant, but also the salt content in a saturated substratea high EC value indicates high electrical conductivity and thus a high level of salt.

EC measurement does not differentiate between individual nutrients nitrogen, phosphorous, potassium and so on , but simply provides the sum total of all salt content. Also, EC measurements cannot determine whether one macronutrient or micronutrient is being absorbed at a higher rate than another. Measuring the EC of the saturated rooting substrate allows the grower to gauge the nutrient needs of the plant. For instance, if the EC value is high in the substrate, there is no need for further fertilizationif it is too high, then flushing with water might be necessary.

Likewise, if the reading is low, this is an indicator that the plant needs some supplementation of nutrients. Make sure that when using an EC probe the substrate is wet as there must be a solution for the current to travel through. One final consideration with EC monitoring is the relationship between salt and water content. As the substrate dries out, the nutrient salt content increasesat this point, the salt concentration might be high enough to damage the roots of the plant. Likewise, if the substrate is constantly flushed with water, the nutrients will be removed completely.

Consider the analogy of having boiling hot or freezing cold water poured onto your skin. Not a pleasant thought! This is especially true with tropical or warm-season plants whose roots are not acclimated to colder temperatures. While watering with cold temperatures might not kill your plants, it could cause root stress and will reduce the absorption of water and nutrients, leading to a slow decline in health.

With regard to watering regimes, avoid the pitfall of establishing a daily routine. Let the plantvia the rooting substratetell you when watering is necessary.

Monitor moisture by touching the top third of the substrate surfaceif it feels moist, delay watering; if it is dry, watering is appropriate.

It is important to note that plants will only use enough water to meet their physiological demands. Generally, plants will not utilize excess water and too much moisture in the substrate forces air out of the interstitial spaces, leading to anaerobic conditions.

Over time, this will lead to roots rotting due to insufficient oxygenation. Essentially, maintaining the proper EC levels prevents overfertilization. Excessive amounts of nutrient runoff from lawns, greenhouses and backyard gardens can enable algal populations to grow exponentially, drastically changing the ecosystem of a waterway.

For example, surface algae can cover the top of a body of water, blocking the path of light to the benthic bottom plants and eventually killing them. Algae will also impact dissolved oxygen levels at night when they respire andmore dramaticallywhen crashes occur due to the bacterial count being so high it causes hypoxia no oxygen.

This can kill off the fish and other aquatic life that are dependent on varying levels of dissolved oxygen, which in turn impacts terrestrial predators that rely on that aquatic food source. There is a direct and critical correlation between EC and plant growth performance. This means that for most plants an ideal EC range should be between one and three milli Siemens per centimeter.

Plants subjected to low nutrient levels low EC will present with nutrient deficiencies. Nutrient deficiencies are caused by poor watering regimes, improper fertilizer rates and improper pH levels. Some nutrient deficiencies a lack of nitrogen, for example can result in the yellowing of leavesespecially older leavesand a very pale green coloration to newer growth. Other signs of a nutrient deficiency include the yellowing of leaf margins and veins, burnt leaf tips and irregular leaf shape.

Fertilizer solutions with a high EC above three can cause burning of the roots due to excessive salt buildup in the substrate. In addition, this accumulation of salts in the substrate and subsequent uptake by the plant roots can result in salt stress. Symptoms of salt stress include necrosis death of the roots and yellowing and wilting of the leaves. Thus, even though nutrient levels might be high the plant might show signs of nutrient deficiencies and drought stress. Depending on the type of plant, the salt concentration and the duration of exposure, a very high EC can quickly lead to plant death.

If overfertilization occurs and the EC is too high, you should immediately flush the substrate with copious amounts of water to remove the salt. It is important to note that signs of salt stress and nutrient deficiencies can be very similar, so proper monitoring of your substrate salt content and moisture is essential for optimal plant health. In conclusion, electrical conductivity EC is an effective way to estimate the fertilizer content via salts in your growing substrate. Monitoring your EC will remove most of the guesswork in meeting the nutritional needs of your plants, resulting in a happier, healthier garden.

The recommendations set forth in this article are by no means set in stonepersonal research will give you the most complete understanding of the ideal growing conditions temperature, lighting, nutrient and water requirements, salt tolerance and so on of each particular plant species.

Hopefully this article has provided enough basic information for you to appreciate the importance electrical conductivity has on monitoring the nutritional needs of your plants. You must be 19 years of age or older to enter this site.

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Written by Bill DeBoer. Full Bio. Related Articles. Electrical Conductivity in the Garden. Master the Art of Measuring EC. Related Terms. Is not tilling better for my soil? My crops are showing salt deposits on the leaf edges. Can you give any advice on how to avoid this problem? More of your questions answered by our Experts.

Related Tags. Plant Nutrition. Plant Growth.

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