The Museum Team's Investigation
At a science museum's mixing comparison bench, visitors examined two clear cups. One held water, and the other held white vinegar. The museum team wanted to investigate whether adding the same powder to these liquids would produce evidence of a new substance. A new substance has properties different from the starting substances. A change in appearance can be a clue, but scientists compare several observations before deciding what happened.
An educator supervised the tests. Everyone wore safety goggles and kept materials away from their mouths and eyes. The team used small amounts of food ingredients in open plastic cups. They did not taste the mixtures or put lids on bubbling cups. Before adding powder, they stirred each liquid for ten seconds. A few small bubbles appeared in both liquids. These bubbles disappeared within five seconds after stirring stopped.
For the mixing tests, the team measured thirty milliliters of water into one cup and thirty milliliters of vinegar into another. Both liquids started at room temperature. They added two grams of baking soda to each cup and stirred each mixture for ten seconds. They used matching cups and the same stirring motion. They changed the liquid, kept the other steps the same, and measured how long visible bubbling continued after stirring stopped.
The team repeated the comparison three times with fresh materials. Small bubbles in the water mixtures disappeared quickly. The vinegar mixtures produced many bubbles that continued after stirring ended. After several minutes, neither mixture had visible baking soda grains. The team recorded bubbling times in the graph. They also noted that a disappearing powder, by itself, did not tell them what substances were present afterward.
At the same bench, the team stirred table salt into water until no grains were visible. They poured this mixture onto a clean tray. After several days, the water had evaporated at room temperature, leaving white crystals. The crystals looked like the starting salt. The team saved both samples for further comparisons instead of deciding from appearance alone.