When examining the conductivity of a solution, what is a key factor that determines the reading?

The key factor that determines the conductivity reading of a solution is the ionic composition of the solution. Conductivity is primarily influenced by the presence of ions in the solution, as these ions are what carry electrical charge. Different types of ions have varying charges and mobilities, which directly affect how well the solution can conduct electricity.

For example, a solution with a high concentration of strong electrolytes, such as sodium chloride, will exhibit much higher conductivity compared to a solution with weak electrolytes or non-electrolytes, which do not dissociate into ions in the same manner. This makes the ionic composition critical in assessing conductivity.

While other factors like temperature can influence conductivity to some extent — as higher temperatures generally increase ion mobility and thus conductivity — the fundamental determinant of conductivity itself is the types and concentrations of ions present in the solution.