Science, Tech, Math › Science Weak Electrolyte Definition and Examples Share Flipboard Email Print Acetic acid is an example of a weak electrolyte even though it is highly soluble in water. ELLA MARU STUDIO / SCIENCE PHOTO LIBRARY / Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Todd Helmenstine Todd Helmenstine is a science writer and illustrator who has taught physics and math at the college level. He holds bachelor's degrees in both physics and mathematics. our editorial process Todd Helmenstine Updated July 19, 2019 A weak electrolyte is an electrolyte that does not completely dissociate in aqueous solution. The solution will contain both ions and molecules of the electrolyte. Weak electrolytes only partially ionize in water (usually 1% to 10%), while strong electrolytes completely ionize (100%). Weak Electrolyte Examples HC2H3O2 (acetic acid), H2CO3 (carbonic acid), NH3 (ammonia), and H3PO4 (phosphoric acid) are all examples of weak electrolytes. Weak acids and weak bases are weak electrolytes. In contrast, strong acids, strong bases, and salts are strong electrolytes. Note a salt may have low solubility in water, yet still be a strong electrolyte because the amount that does dissolve completely ionizes in water. Acetic Acid as a Weak Electrolyte Whether or not a substance dissolves in water is not the determining factor in its strength as an electrolyte. In other words, dissociation and dissolution are not the same things. For example, acetic acid (the acid found in vinegar) is extremely soluble in water. However, most of the acetic acid remains intact as its original molecule rather than its ionized form, ethanoate (CH3COO-). An equilibrium reaction plays a big role in this. Acetic acid dissolves in water an ionizes into ethanoate and the hydronium ion, but the equilibrium position is to the left (reactants are favored). In other words, when ethanoate and hydronium form, they readily return to acetic acid and water: CH3COOH + H2O ⇆ CH3COO- + H3O+ The small amount of product (ethanoate) makes acetic acid a weak electrolyte rather than a strong electrolyte.