Which type of compound cannot be split into ions by electrolysis?

• A. Ionic compounds
• B. Covalent compounds
• C. Acids
• D. Metals

Answer: (B)

Electrolysis needs free charged particles to move in an electric field. Ionic compounds, when melted or dissolved, separate into positive and negative ions, so they can be decomposed by electrolysis. Acids in solution also dissociate into ions, which allows their components to be split by the electric current. Covalent compounds, however, are held together by shared electrons and do not form ions in the melted or dissolved state, so there are no free charges to carry the current and they don’t decompose into ions by electrolysis. Metals aren’t compounds and conduct via delocalized electrons rather than ions, so they aren’t described as being split into ions by electrolysis. Therefore, covalent compounds cannot be split into ions by electrolysis.