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Electrolytes are substances that dissolve in water and dissociate into ions. Substances can be classified into three categories: strong electrolytes, weak electrolytes, and nonelectrolytes. Strong electrolytes dissociate completely into ions when dissolved in water. These include ionic compounds (salts) such as sodium chloride, which dissociates in water to form Na ^+ and Cl ^- ions. Strong electrolytes also include strong acids, which react completely with water to produce ions (Cl ^- and hydronium H_3O^+ ). Solutions containing strong electrolytes are good conductors because the ions produced when these substances dissociate allow the solution to conduct electricity.

Weak electrolytes are substances, when dissolved in water, only a fraction of the molecules dissociate into ions. These include weak bases and weak acids. Broadly speaking, weak bases contain an amine functional group. Weak bases, such as ammonia ( NH_3 ), partially react with water to form ions. In the case of ammonia, NH_4^+ and OH^- ions are produced. Only a small fraction of ammonia reacts to form these ions, and thus the vast majority of the ammonia molecules remain neutrally charged. Since very few ions are produced, solutions of weak bases are poor conductors. Similarly, weak acids are acids that only partially react with water to produce ions. A weak acid is an acid that isn't one of the seven strong acids. Typically, an inorganic acid's molecular formula starts with an H. Organic acids contain a carboxylic acid functional group. An example is acetic acid ( CH_3COOH ). A minor fraction of acetic acid reacts with water to form acetate ( CH_3COO^- ) and hydronium ions, but the majority of acetic acid does not react and instead remains neutrally charged. Since very few ions are produced, solutions of weak acids are poor conductors.

Nonelectrolytes are substances that do not dissociate into ions when dissolved in water. An example is glucose, which remains neutrally charged when dissolved in solution. Since no ions are produced, solutions of nonelectrolytes are nonconductive.

Additionally, you are welcome to watch this video demonstration which illustrates the differing conductivity of various solutions.  As the metal rods are placed into each solution, the free-floating ions (if any) in the solution will complete the circuit and allow electricity to flow through the light bulb, lighting it up. The larger light bulbs are a higher power rating (wattage), and therefore requires a greater conductivity to light up. So, for each solution tested, more more light bulbs/larger the bulbs it alights, the more conductive it is. 

For each of the solutions tested, can you tell if they are strong, weak, or non-electrolytes?

• 1 ^st solution: acetic acid (vinegar)
• 2 ^nd solution: hydrochloric acid
• 3 ^rd solution: distilled water
• 4 ^th solution: sugar
• 5 ^th solution: salt water
• 6 ^th solution: methanol
• 7 ^th solution: Gatorade