Electrical Conductivity of Liquids

Introduction to Experiment

Aim of this experiment is to show that acids, bases, and salts are electrolytes. Electrolytes conduct current with ions and not electrons like metals. Acids, bases, and salts are examples of electrolytes. In this experiment, we will understand that acids, bases and salts are electrolytes with the help of an electric continuity test. 

1. In strong acid (HCl), electric current is well conducted by the acid dissociating into H⁺ and Cl^–. Thus, it is an electrolyte.
2.  In a strong base (NaOH), electric current is well conducted by the base dissociates into Na⁺ and OH^–. Thus, it is an electrolyte. 
3. In an aqueous solution, NaCl dissociates into ions that are free to move around and conduct electricity. Thus, the bulb glows. Electric current is well conducted by the salt dissociates into Na⁺ and Cl^–. Thus, it is an electrolyte.
4. In the case of distilled water, the bulb does not glow when the key is plugged in because the electric current never passes through the distilled water as it doesn’t readily dissociate into ions like HCl, NaOH and NaCl. 

Apparatus and Materials Required

Apparatus

• Beaker- 100 mL 
• Battery 
• Battery holder
•  Bulb 
• Bulb holder
• Rubber cork
• Iron nails
• Plug key
• Connecting wire
• A piece of sandpaper
• Glass rod
• Spatula 

Chemicals

• Concentrated Hydrochloric acid  
• Sodium hydroxide flakes
• Sodium chloride
• Distilled water

Procedure

The following steps to follow for the procedure:

1. By using sandpaper, clean the insulation layers from the ends of the connecting wires.
2. Fix two iron nails in a dry rubber cork at a distance. These will serve as electrodes. Also, connect these two nails separately with connecting wires. 
3. Form the circuit for performing an electric continuity test that contains either an acid or a base or a salt solution as a part of it.
4. Connect the different components, like the battery to the battery holder, the bulb to the bulb holder, a plug key, and the electrolytic solution to the circuit.
5. Take four beakers (250 mL) and add 100 mL of distilled water into each beaker. Label them as beakers ‘A’, ‘B’, ‘C’, and ‘D’. 
6. Convert the beaker ‘A’ into an acidic solution by adding five drops of HCl into it. Similarly, dissolve 100 mg of NaOH in beaker ‘B’ to prepare a basic solution, and add about 2-3 g of sodium chloride salt to beaker ‘C’ to get a sodium chloride salt solution. Add nothing to the distilled water in beaker ‘D’.
7. Fix two iron nails into the rubber cork and connect them to the circuit without dipping them in any beaker. Insert the key into the plug. The electric bulb does not glow, as the rubber cork does not conduct electricity. Remove the key from the plug. 
8. Now, place the rubber cork in the beaker ‘A’ such that the two iron nails are partially dipped in the solution, and insert the key into the plug to observe electric continuity. 
9. The bulb glow indicates that the electric circuit is now complete and that the hydrochloric acid conducts electricity. Thus, it is an electrolyte. Record your observations.
10.  Remove the key from the plug. Take out the rubber cork from the beaker ‘A’, and wash it thoroughly and keep it dry to use in the next beaker. 
11.  Now, repeat the same procedure performed for beaker ‘A’ with the remaining beakers to observe their electrical conductivity and record the observations for every beaker. 

In this experiment, we conclude that an electric continuity test is performed for the chemicals, namely, dilute HCl, dilute NaOH, NaCl solution and distilled water.

When distilled water is connected to the electric circuit, the bulb doesn’t glow, indicating that the ions formed are so small and negligible so that electric current doesn’t pass through the circuit. 

Hence, distilled water is a non-electrolyte.

When the electric circuit is made to complete with acid, base and salt solution separately, the bulb starts glowing due to the dissociation of ions in water, and these ions are responsible for the passage of electricity.

FAQs on Electrical Conductivity of Liquids