Question

On first glance, both table salt, $NaCl$, and ordinary table sugar, sucrose, $C_{12}{H}_{22}{O}_{11}$, appear very similar; both are white, crystalline solids. Of the four possibilities listed below, which one would be a useful test to distinguish between table salt and sucrose? Tasting of chemicals in the laboratory is never an option, so it has not been included.

• A. Test electrical conductivity in the solid state
• B. Test to see if the solid is water soluble
• C. Test electrical conductivity in aqueous solution
• D. Test the pH of an aqueous solution of the substance

Answer 1

The correct option is C Test electrical conductivity in aqueous solution

Table salt $\left(NaCl\right)$ conducts electricity in aqueous solution because it has ions that have the freedom to move about in solution. These ions are produced when sodium chloride dissolves in pure water in the form of sodium $\left(N{a}^{+}\right)$ and chloride ions $\left(C{l}^{-}\right)$ while on the other hand ordinary table sugar, sucrose $\left(C_{12}{H}_{22}{O}_{11}\right)$ solution does not conduct electricity because sugar, 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.
Thus, $\left(C\right)$ is right answer.