Science experiments involving acids and bases require\ a strict control of health and safety, particularly if you are carrying out investigations with children. Be aware of the chemical reactions that will occur when you mix certain acids and bases together, as mixing some chemicals leads to sudden and violent reactions. When handling acids and bases you should always use the appropriate safety equipment, such as wearing a white laboratory coat or overall, thick rubber gloves and safety goggles, as acid or base contact with the skin or eyes can be extremely unpleasant.
Using red cabbage leaves as a pH indicator is a classic chemistry experiment that you can complete easily at home or in the classroom. Line up three identical plastic cups and label them "acid," "base" and "neutral." Add teaspoons of pure vinegar, baking soda and distilled water to each of the cups respectively, using a different teaspoon for each substance to avoid contaminating the samples. In a separate mixing bowl, tear up the leaves of a red cabbage before submerging them in distilled water and pressing the leaves using the back of a spoon. Leave this solution for 20 minutes before pouring it through a strainer and collecting the runoff liquid in a fresh bowl. Add five drops of the red cabbage solution into each of the plastic cups using a medicine dropper. Observe the color change in each cup — the liquids turn red, blue and purple, indicating acidity, alkalinity and neutrality on the pH scale.
An example of an interesting acid base experiment you can conduct quickly and simply shows you how you can inflate a balloon without using your breath. Take a regular empty soda bottle that holds, at the most, 1/2 liter and add 2 tablespoon of vinegar, which is the experiment acid. Stretch out the neck of a balloon before adding 2 tablespoon. of the base — baking soda — inside the balloon. Attach the neck of the balloon to the opening of the bottle so that the baking soda remains inside the balloon. Once you are ready to commence your experiment, raise the balloon so the baking soda drops into the bottle and mixes with the vinegar. Stand back and observe as the carbon dioxide produced by the acid base reaction rises and inflates the balloon.
Carry out this experiment to investigate whether the acidity of a onion affects the acridity of its flavor. Take several different types and sizes of onion, including regular onions, shallots and red onions. Carefully cut each onion in half, asking an adult for help if you are a science student completing this research. Smear a pH testing strip on the inside of the onion before leaving it to one side so it can dry. Taste a small cutting of the onion as you wait for the pH strip to dry and rate it out of 10 for acridity, with 10 being the most acrid. Note down your acridity rating for each onion before writing down its pH, as indicated by the testing strip, beside it. Compare the acridity and acidity scores for each onion once you have tested each vegetable.