Repeat step 3b with the H 2 SO 4 . Be sure to rinse the tester in distilled water to clean it. Stop when the light goes out. Check the cup at this point with litmus and pH papers. Clean the tester with distilled water.
Students return to their seats with their results.
Discuss the results. Only solutions that contain ions conduct electrical current. 2 SO 4 solutions must contain ions, but distilled water does not. Phenolphthalein is pink in the presence of a base but colorless in the presence of an acid. This suggests that the solution in the beaker changes color just when no more base is present.