Water and Solubility Demonstrations

See also: Water Cycle, Fluids and Surface Tension

Water is often called the universal solvent because of its ability to dissolve many substances. This category looks at how solubility works, the factors that affect it, and why it is important in natural systems and daily life. Understanding solubility also provides insight into broader chemical ideas such as solutions and concentration.

Demonstration	Materials	Difficulty	Safety	Summary
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.
Borax Crystal Snowflakes	★★☆	★★☆	★★☆	Make snowflake ornaments from pipe cleaners by growing borax crystals from a hot, supersaturated solution. Compare color methods (colored pipe cleaners, food coloring, or post-painting with watercolors) and observe how crystals form and how color moves through the crystal structure.
Bubbling Lava Lamp	★☆☆	★☆☆	★☆☆	Two versions of a homemade lava lamp can be created using common household materials. In one, baking soda and vinegar react to produce bubbles that carry colored water through oil. In the other, antacid tablets release carbon dioxide bubbles that produce the same effect.
Candy Chromatography	★☆☆	★☆☆	★☆☆	Paper chromatography is used to separate the dye mixture from colored candy coatings and compare the separated spots to known food colorings. Measure and compare Rf values to infer which approved food dyes are present.
Copper Sulfate Crystals	★★☆	★☆☆	★★☆	A perfect seed crystal is grown in a shallow dish, then suspend the seed in a saturated, undisturbed solution so it enlarges slowly into a clear, well-formed single crystal. Careful control of saturation, evaporation, and disturbances is the key to size and quality.
‘Dissolving’ Styrofoam in Acetone	★★☆	★★☆	★★☆	When expanded polystyrene foam is placed in acetone (propanone), it appears to dissolve, dramatically shrinking in volume. This striking demonstration shows how acetone breaks down the foam structure by dissolving the polystyrene polymer, leaving only a small residue of solid polymer behind.
Endothermic and Exothermic Dissolving	★★☆	★☆☆	★★☆	This demonstration compares two reactions: one that absorbs heat from the surroundings (endothermic) and one that releases heat (exothermic). Students can observe changes in temperature and feel whether the container becomes hot or cold.
Cleaning Water With Flocculation	★★☆	★★☆	★☆☆	Students clean real pond or river water using two flocculants, aluminum sulfate and a polymer clarifier. They compare how stirring and lowering pH with lemon juice affect how fast particles clump and settle.
Homemade Water Purifier Model	★☆☆	★☆☆	★☆☆	Students build a simple water filter using a cut plastic bottle and layers of materials like sand, gravel, cotton, and activated charcoal. The experiment shows how filters remove impurities from dirty water, though the filtered water is not safe to drink.
Instant Snow Polymer	★★★	★☆☆	★★☆	A small amount of instant snow polymer rapidly absorbs water and swells to many times its original volume, creating fluffy “snow and causing a temperature change.
Lead Iodide Precipitation	★★☆	★☆☆	★★☆	When aqueous lead(II) nitrate reacts with aqueous potassium iodide, a double displacement reaction occurs. Potassium nitrate remains dissolved, while lead(II) iodide precipitates as a bright yellow solid.
The Lost Volume Demonstration	★☆☆	★☆☆	★☆☆	Equal volumes of water and ethyl alcohol do not add up to their combined total volume when mixed. Instead, the mixture shows a reduced volume due to molecular interactions between water and alcohol.
Oil and Water Emulsification	★☆☆	★☆☆	★★☆	Oil and water normally separate into layers, but adding soap or detergent allows them to mix temporarily. This demonstrates how emulsifiers work by suspending oil droplets in water.
Rock Candy	★★☆	★★☆	★★☆	Dissolve sugar into hot water until it forms a supersaturated solution, then suspend sugar-coated sticks in jars to grow edible sugar crystals over several days. Color or flavor can be added to make decorative, tasty rock candy.
Crystallization of Sodium Acetate	★★☆	★★☆	★★☆	A hot, concentrated solution of sodium acetate trihydrate is cooled quietly to create a supersaturated liquid. When poured onto seed crystals, it crystallizes instantly to build a warm, solid tower.
Soil Field Capacity	★★☆	★☆☆	★☆☆	Different soil types are tested for field capacity by adding water and measuring how much each soil retains after drainage, showing how soil properties affect water holding capacity.
Water on a Coin	★☆☆	★☆☆	★☆☆	Using an eyedropper, drops of water are placed on a coin and it's observed how many drops can pile up before spilling over. The activity demonstrates cohesion, adhesion, and surface tension in water compared with other liquids like oil and syrup.

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