with Kim Rodgers
This week in Chemistry we learned about acids and bases. A base has an OH group (an oxygen atom and a hydrogen atom) and an acid has an H group (just a hydrogen atom). Both acids and bases are important and needed in lots of very useful reactions. We learned that acids generally
taste sour and bases taste bitter and are slippery.
We put our new found knowledge to the test through an experiment. We had 7 liquids: white grape juice, lemon juice, grapefruit juice, milk, baking soda water, mineral water, and water with alka-seltzer tablets. The students first made predictions whether they thought each liquid would be “sour” or “not sour.” I made it clear that the liquid might not taste very good, but that didn’t mean it was sour. Some of them might taste more bitter. It’s very easy to find foods that are acidic, but more difficult to find foods that are basic. The only two safe ones used in our experiment were baking soda water and the antacid. Most household cleaning products are basic, but they obviously aren’t safe to taste!
After they made their predictions, we tested them. The students tasted the liquids and determined if their predictions were correct or not. If a student didn’t want to try one, they relied on their classmates' opinion on whether the liquid was sour or not. We decided that the only two liquids that were actually sour were the lemon juice and the grapefruit juice.
Next we used an indicator (red cabbage water that I had boiled the day before) to see if there was a change in color. The milk turned a gray color, but we thought that was because we added a deep purple color to a creamy white color, so we decided there wasn’t color change, per se. The mineral water also didn’t change much. The white grape juice, lemon juice, and grapefruit juice changed to pink. The antacid and the baking soda water changed to an oily black color with maybe a green tinge next to the edge of the glass. The liquids that turned the cabbage juice pink are called acids and the liquids that turned the juice blackish green are called bases. Some liquids like milk don’t change color much because they are neutral, which means they aren’t acids or bases.
For Next Week...
For our project the students and I went over the symbolism used in the coat of arms knights used on their shields. People couldn’t tell which knight was which in battle because they were covered in armor from head to foot. Their coat of arms was what gave them away. The students used colors, animals, and symbols to make a coat of arms representing themselves. They took these home to finish if they needed to. Please have them bring them back next week to share, along with their mapping and notebooking pages.