Bases conduct electricity when they are dissolved in water or heated until they melt. In a water solution, bases typically release a specific negative particle called hydroxide (\(\text{OH}^-\)). This process of dissolving allows the substance to become electrically conductive by creating mobile, charged particles.
The Role of Ions in Electrical Conductivity
For any liquid to carry an electrical current, it must contain mobile, charged particles (ions). Unlike metal wires where electrons carry the charge, in liquids, the charge is carried by atoms or molecules that have gained or lost electrons, which must be free to move to facilitate current flow.
Pure water is a very poor conductor of electricity because it contains very few of these necessary charged particles. The water molecules themselves do not carry a net charge, and only a tiny fraction naturally separates into charged components. When a substance dissolves in water and breaks apart into charged components, it creates the necessary conditions for electrical conduction.
The ability of a liquid to conduct electricity is directly related to the concentration and mobility of these charged particles. The greater the number of mobile charges in the solution, the more easily the electrical current can flow through it. This principle applies universally to all conducting solutions, whether they are made from salts, acids, or bases.
How Bases Dissolve to Create Conductive Solutions
When a base is introduced into water, its component parts separate, creating the mobile charged particles needed for conduction. A common example is sodium hydroxide, a base often used in cleaning products, which immediately splits apart when dropped into water.
The sodium hydroxide molecule separates into two distinct parts: a positively charged sodium particle (\(\text{Na}^+\)) and a negatively charged hydroxide particle (\(\text{OH}^-\)). The splitting of the base into these two types of charged components is called dissociation. These newly freed, charged particles are now dispersed throughout the water.
The positively charged sodium particles move toward the negative terminal of an electrical circuit, while the negatively charged hydroxide particles move toward the positive terminal. This coordinated movement of oppositely charged particles in opposite directions is the flow of electricity through the base solution. The mobility of these charged components allows the solution to conduct electricity.
Measuring Conductivity: Strong Versus Weak Bases
The degree to which a base conducts electricity is not uniform across all basic substances. This difference in conductivity is directly related to how completely the base separates into its charged components when dissolved. Bases that separate completely, such as sodium hydroxide, are classified as strong bases.
Strong bases are highly conductive because nearly every molecule of the substance breaks apart, flooding the solution with a high concentration of mobile charged particles. This high concentration allows a strong and steady electric current to pass through the solution, which can be measured using a conductivity meter.
In contrast, some bases only separate partially when dissolved in water; these are known as weak bases. Ammonia (\(\text{NH}_3\)) is a common example of a weak base, where only a small percentage of the molecules react with water to form the necessary charged components. At any given moment, the solution contains fewer mobile charged particles than a strong base solution of the same concentration.
Because weak bases produce fewer charged components, they are less conductive than strong bases. The electrical conductivity of a base solution serves as a direct measure of its strength, indicating the proportion of molecules that have successfully dissociated.