Question

Why sugar solution is not a good conductor but salt solution is?

Answer 1

Salt solution such as sodium chloride (NaCl) conducts an electric current because it has ions in it that have the freedom to move about in solution. These ions are produced when sodium chloride dissolves in pure water to produce sodium (Na+) and chloride ions (Cl–).

When you insert the electrodes of a conductivity tester in the salt solution, the positive sodium ions usually move to the negative electrode, while the negative chloride ions move to the positive electrode. This movement of ions to opposite ends of the electrodes allow electric current to flow through the solution.

On the other hand, sugar solution does not conduct an electric current because sugar (C12H22O11) dissolves in water to produce sugar molecules. These sugar molecules are usually neutral (not charged), and so are unable to move to the opposite ends of the electrodes like the ions.