Acids and Bases Demonstrations

Acids and bases are substances that play an important role in chemistry, everyday life, and the natural world. This category introduces the concepts of acidity and alkalinity, how they can be measured, and the reactions that occur when acids and bases interact. Understanding acids and bases provides a foundation for exploring chemical change and the ways substances behave in different environments.

Demonstration	Materials	Difficulty	Safety	Summary
Naked Egg (Bouncy Egg)	★☆☆	★☆☆	★☆☆	When an egg is placed in vinegar, the acid reacts with the calcium carbonate of the eggshell, producing carbon dioxide bubbles and dissolving the shell. What remains is a soft, rubbery membrane that can stretch and even bounce.
Universal pH Test Paper	★★☆	★☆☆	★★☆	Universal pH test paper provides a quick way to estimate whether a solution is acidic, neutral, or basic. By dipping strips into common household solutions, students can learn how different substances fall along the pH scale.
Mass of Air	★★☆	★☆☆	★☆☆	Two balloons are balanced on a yardstick, and when one balloon is filled with air, it tips the balance, proving that air molecules have mass and are pulled down by gravity. A balloon can also be weighed empty and full on a precise scale.
Testing pH Indicators	★★☆	★☆☆	★★☆	This experiment investigates how different pH indicators change color across the acidic, neutral, and basic ranges.
Bubbling Slime	★★☆	★☆☆	★☆☆	This experiment combines vinegar, xanthan gum, and baking soda to make bubbling slime. The vinegar and baking soda undergo an endothermic chemical reaction, releasing carbon dioxide gas that bubbles through the gooey slime.
Water to Wine to Milk to Beer	★★☆	★★☆	★★★	This dramatic chemistry demonstration makes a liquid appear to transform into water, wine, milk, and beer as it is poured from one glass to another. The sequence involves pH indicators, precipitate formation, and gas release, illustrating multiple chemical concepts in a visually striking way.
Water Into Wine	★★☆	★☆☆	★☆☆	This demonstration uses the pH indicator phenolphthalein and sodium carbonate to make water appear to turn into wine or blood. The liquid changes from colorless to pink or red under basic conditions, and can be reversed to clear again by adding acid or blowing carbon dioxide into the solution.
Neutralization of Acid and Base	★★☆	★★☆	★★☆	This demonstration shows the neutralization reaction between sodium hydroxide and dilute hydrochloric acid. The acid is added drop by drop to the base while monitoring the change in pH with red litmus paper until the solution reaches neutrality.
Acid In The Eye	★★☆	★★☆	★★★	This demonstration shows how strong acids and bases irreversibly damage proteins using egg whites as a model for the human eye. When acid is dropped on egg white, it denatures the proteins, turning them opaque and simulating permanent eye damage.
Burning Sulfur to Simulate Acid Rain	★★☆	★★☆	★★☆	Sulfur is burned in air to form sulfur dioxide gas, which dissolves in water. The dissolved gas produces sulfurous acid, lowering the pH and turning universal indicator solution red to simulate acid rain.
Red Cabbage Indicator	★☆☆	★★☆	★★☆	Red cabbage contains a pigment called anthocyanin that changes color depending on whether a substance is an acid, base, or neutral. By extracting this pigment, you can test common household liquids to see where they fall on the acid-base scale.
Milk of Magnesia Changing Colors	★★☆	★★☆	★★☆	Milk of magnesia, a suspension of magnesium hydroxide, is mixed with a universal indicator to show its alkaline nature. When vinegar is added, the solution rapidly shifts through the color spectrum as the acid reacts with the base, demonstrating how antacids neutralize stomach acid.
pH Indicator Easter Eggs	★★☆	★☆☆	★☆☆	Eggs are dyed with red cabbage extract, which contains the natural pH indicator anthocyanin. Applying acidic or basic solutions changes the color of the dye, allowing designs, messages, or patterns to be revealed on the eggs.
Ammonia Fountain	★★★	★★★	★★★	Dry ammonia gas is collected in a sealed flask. When a small amount of water is injected, the ammonia rapidly dissolves, creating a partial vacuum that pulls water up into the flask. An indicator shows the resulting alkaline solution.
Ammonia and Hydrogen Chloride Diffusion	★★☆	★★☆	★★★	Cotton wool soaked with aqueous ammonia is placed at one end of a glass tube and cotton wool soaked with concentrated hydrochloric acid at the other. As the vapors diffuse toward each other, they form a visible white ring of ammonium chloride closer to the HCl end, showing that ammonia diffuses faster due to its lower molar mass.
Ocean Acidification	★★☆	★☆☆	★☆☆	By blowing air through water containing a pH indicator, students can observe how dissolved carbon dioxide lowers the pH of water, demonstrating the process of ocean acidification.
Red Cabbage Rainbow pH Indicator	★☆☆	★☆☆	★★☆	Boiled red cabbage produces a purple solution containing anthocyanin, a natural pigment that changes color when exposed to acids or bases. Students can use this homemade pH indicator to test household substances and create a rainbow of colors across the pH scale.
Dry Ice pH Colour Change	★★★	★★☆	★★☆	Adding dry ice to a beaker of water with universal indicator creates bubbling fog and a color change. As carbon dioxide dissolves into the water, the solution becomes acidic and shifts from green through the color spectrum to orange. Adding base resets the cycle.
[New Demonstration]	★★★	★★☆	★★☆	A disappearing ink solution is created using the acid-base indicator thymolphthalein. It appears dark blue when basic, but fades to colorless as carbon dioxide from the air lowers the pH. The fading can be sped up with vinegar or slowed down with additional base.

Materials
★☆☆ Easy to get from supermarket or hardware store
★★☆ Available in most school laboratories or specialist stores
★★★ Requires materials not commonly found in school laboratories

Difficulty
★☆☆ Can be easily done by most teenagers
★★☆ Available in most school laboratories or specialist stores
★★★ Requires a more experienced teacher

Safety
★☆☆ Minimal safety procedures required
★★☆ Some safety precautions required to perform safely
★★★ Only to be attempted with adequate safety procedures and trained staff