Kylie has two glasses with equal volumes of pure water. She adds 40 g of sugar to one of the glasses of water and 40 g of salt to the other. When sugar is dissolved in water, it does not change the number of ions present. When salt is dissolved in water, however, the number of ions significantly increases.

Question

Which of the following is true about the electrical conductivity of Kylie's two solutions?
A.
Pure water will have a higher conductivity than both the sugar water and the salt water.

B.
The solution of sugar water will have a higher conductivity than the solution of salt water.

C.
The solution of salt water will have a higher conductivity than the solution of sugar water.

D.
The solution of salt water and the solution of sugar water will have the exact same conductivity.

Answer 1

The correct option is:

C. The solution of salt water will have a higher conductivity than the solution of sugar water.

Here’s the reasoning:

• Pure water has very low conductivity because it has very few ions.
• When sugar is dissolved in water, it does not dissociate into ions; it remains as sugar molecules, which do not conduct electricity. Therefore, the conductivity of the sugar solution is relatively low, but still higher than pure water due to the presence of sugar molecules.
• When salt (sodium chloride, NaCl) is dissolved in water, it dissociates into sodium ions (Na⁺) and chloride ions (Cl⁻). This process significantly increases the number of ions in the solution, which enhances its ability to conduct electricity.

Thus, the saltwater solution will have a much higher electrical conductivity compared to the sugar water solution.