Question

Semi-related to Why do some salt ions in solution conduct electricity better than others?

After conducting more experiments, using deionised water as an analyte only, I found the potential difference decreases as more silver nitrate is added. This goes against what I was lead to believe that it is actually disruption in forms of pure water that actually conduct electricity (i.e. pure water should not technically conduct electricity at all). This graph shows how the potential difference drops, from my findings. The last data points plotted are at 1cm3 of silver nitrate added; the interval is 0.05cm3. So, why is it that I see a massive drop in potential when even the slightest (0.50cm3) amount of silver nitrate is added?

Answer 1

When silver nitrate is added to deionised water, it releases ions that should increase the conductivity. However, the observed potential difference decreases, suggesting other factors at play such as precipitate formation, which interferes with ion mobility and thus conductivity.

Step-by-step explanation:

The student is observing a drop in potential difference when adding silver nitrate to deionised water, which is puzzling because they expected that pure water would not conduct electricity, and any addition should increase conductivity. The ionic compounds in the solid state, like sodium chloride, do not conduct electricity due to the immobility of ions within the crystal lattice.

When these compounds dissolve in water, the lattice breaks, releasing ions that move freely and conduct electricity. Thus, as silver nitrate is added to deionised water, it dissolves and ionizes, increasing the number of mobile charged particles responsible for conducting electrical current.