Electrolytes

Sports drinks, like the one shown in Figure 23, taste salty because they contain salts of elements such as sodium, potassium, and calcium. Salts are examples of electrolytes. An electrolyte is a substance that ionizes or dissociates into ions when it dissolves in water. The resulting solution can conduct electric current. The electrolytes in sports drinks help restore the balance of ions in your body.

Electrolytes can be classified as strong or weak. Strong acids and bases are strong electrolytes because they dissociate or ionize almost completely in water. For example, sodium hydroxide is a strong electrolyte that produces many ions in water. Salts are also strong electrolytes. When potassium chloride dissolves in water, it dissociates into potassium and chloride ions. In contrast, acetic acid is a weak electrolyte because it only partially ionizes.

Batteries and other portable devices that produce electricity also contain electrolytes. Car batteries use lead plates in combination with the electrolyte sulfuric acid to produce electricity. Space shuttles use devices called fuel cells that provide electricity to power all the crafts' devices. Fuel cells use the strong base potassium hydroxide as an electrolyte. Instead of metal electrodes, the fuel cells use oxygen and hydrogen brought from Earth. At the same time that the fuel cells provide electrical energy to power a space shuttle, they also produce water that the crew can use.

Figure 23 Drinking sports drinks after exercising can restore the balance of ions in your body.