Acids and Bases: What happens when H+ ions dissociate
Today was all about acids and bases. Students put on their safety goggles and investigated how scientists classify acids and bases using the pH scale. The lesson began by teaching our young scientists about ions, an atom that loses or gains an electron. Once atoms become ions and are charged, they can attract or repel each other, like magnets. This is how acids and bases react. We introduced the pH scale, so they understood how scientists measure the acidity or basicity of a solution.
We then predicted what we thought the pH would be for several common substances found in every day life, including ammonia, vinegar, cola, baking soda, borax, milk and the tap water at CHA! We tested the pH of the solutions using indicator strips and compared the actual pH with the previously predicted pH.
The students then used red cabbage juice as an acid/base indicator. The dark purple color in the cabbage comes from a pigment called anthocyanin, which changes color depending on pH. Acids made the purple juice from the red cabbage turn red, while bases made the purple juice turn green. Looking at the color change, the students then decided whether the solution was an acid or a base, and if it might be a strong or weak acid/base. The young scientists were shocked to discover that some solutions were extremely acidic or basic and found that soda is very acidic–sugar isn’t the only reason it is bad for your teeth!
This is an AWESOME video about what happens to an “aluminium” coke can in a strong acid (HCl “hydrochloric acid”) and a strong base (NaOH “sodium hydroxide), the same liquids you saw today!