For example, water does have a pH and it does conduct electricity. Impurity particularly CO 2 picked up from the air is the source of these readings. Water also ionizes a small extent again giving background pH and conductivity measurements. To answer this you need to measure pH and conductivity of distilled water. Another problem when making measurements is how to decide if differences are significant.
Experience helps and so does statistical decision making methods.
We want you to learn to recognize the difference between large differences due to differences in the system and differences due to randomness in samples. We want you to do this in a qualitative way. To do this, we will supply two other baseline samples that you should use to see differences between conducting electricity and conducting electricity a small amount. Dissolving or not dissolving in water together with conductivity measurements are necessary but not sufficient ways to distinguish between pure substances. You will investigate if pH measurement and the behavior of the substance in the presence of acid or base can provide additional levels of classification.