Particles and States of Matter Demonstrations

The particle model explains the properties of solids, liquids, and gases by considering the motion and arrangement of particles and the forces between them. This category examines changes of state, diffusion, gas pressure, and how temperature affects particle movement. Using the model helps link microscopic ideas to macroscopic observations such as expansion, compressibility, dissolving, and viscosity. Mastery of the particle view supports reasoning across many areas of science.

Demonstration	Materials	Difficulty	Safety	Summary
Boiling Cold	★★★	★★☆	★★★	This demonstration uses liquid butane in a plastic bag to show evaporation and boiling under reduced pressure. As the butane evaporates, it absorbs heat, cooling the bag and causing condensation of water vapor on the outside.
Boiling Water in a Vacuum Chamber	★★★	★★★	★★★	When water is placed in a vacuum chamber and the air is pumped out, the reduced external pressure lowers the boiling point. The water boils at room temperature, and because the energy for vaporization comes from the liquid itself, the remaining water cools noticeably.
Brownian Motion in a Smoke Cell	★★★	★★☆	★★☆	This classic experiment demonstrates Brownian motion by observing tiny smoke particles under a microscope. Their random, jittery movement provides strong evidence for the particulate nature of matter and the constant motion of gas molecules.
Freezing Flowers With Dry Ice and Alcohol	★★★	★★☆	★★★	A mixture of dry ice and isopropyl alcohol creates a very cold liquid at around -90 °C, which can instantly freeze flowers, candy, or fruit, making them brittle and easy to shatter.
Gallium and Aluminium Can	★★★	★☆☆	★★☆	When liquid gallium is applied to an aluminum can, it penetrates the aluminum’s grain boundaries and disrupts its crystal structure, making the can brittle and easy to puncture.
Light a Match With Superheated Steam	★★★	★★☆	★★★	Steam produced at atmospheric pressure is passed through heated copper tubing to become superheated, reaching several hundred degrees Celsius. The superheated steam demonstrates surprising effects when it comes into contact with paper and matches.
Marshmallow in a Vacuum	★★★	★★☆	★★☆	Placing marshmallows inside a bell jar and changing the air pressure demonstrates how gases expand and contract, showing the effects of vacuum and differential pressure on porous materials.
Melting Gallium in Your Hand	★★★	★☆☆	★★☆	Gallium, a metal with a melting point of 29.76 °C (85.6 °F), can melt in the palm of your hand. The demonstration shows how body heat is enough to turn solid gallium into a silvery liquid.
Triple Point of Water	★★★	★★★	★★★	This demonstration shows the triple point of water - the unique conditions of temperature and pressure where water exists simultaneously as a solid, liquid, and gas. By cooling water and lowering the air pressure inside a bell jar with a vacuum pump, students observe water boiling, freezing, and melting at the same time.
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.
Balloon in Syringe Boyle's Law	★★☆	★☆☆	★☆☆	Using balloons inside a syringe, this experiment shows how gases expand when pressure decreases and contract when pressure increases, illustrating Boyle’s law.
Boiling Water at Room Temperature	★★☆	★☆☆	★★☆	By pulling back the plunger on a water-filled syringe with the tip sealed, the pressure inside is reduced. This causes the water to boil at room temperature, demonstrating how boiling depends on pressure as well as temperature.
Cloud in a Bottle	★★☆	★★☆	★★☆	This demonstration shows how changes in pressure and temperature can create visible clouds. When air inside a sealed bottle containing rubbing alcohol is compressed and then suddenly released, the vapor condenses into tiny suspended droplets, forming a cloud.
Comparing Evaporation Rates	★★☆	★★☆	★★☆	This demonstration shows how different liquids evaporate at different rates by measuring their temperature changes during evaporation. Students connect differences in evaporation rates to molecular structure and intermolecular forces using molecular models.
Compressing Solids, Liquids and Gases	★★☆	★☆☆	★☆☆	This demonstration uses syringes filled with air, water, and solid pellets to show that gases are compressible while liquids and solids are not. It models how the spacing between particles differs among solids, liquids, and gases.
Freeze a Beaker to a Board	★★☆	★★☆	★★☆	When ammonium nitrate and barium hydroxide are mixed, they undergo a strongly endothermic reaction that absorbs heat, lowering the temperature to around –25 °C to –30 °C. The beaker becomes so cold that water freezes, bonding the beaker to the wooden block beneath it.
Sublimation of Iodine	★★☆	★★☆	★★☆	Elemental iodine can be heated to show sublimation, where it changes directly from a solid to a purple vapor and then recrystallizes on a cooled surface without passing through a liquid phase.
Sublimation of Naphthalene	★★☆	★☆☆	★★☆	A mixture of impure naphthalene and sand is heated to demonstrate sublimation. Naphthalene sublimes directly from solid to vapor and recrystallizes on a cooled surface, separating it from the non-sublimable impurity.
Thermal Decomposition of Ammonium Chloride	★★☆	★☆☆	★★☆	Ammonium chloride, when heated, undergoes decomposition into hydrogen chloride and ammonia gasses, before reforming when cool. The process appears similar to sublimation and deposition.
Balloon Volume and Temperature	★☆☆	★☆☆	★☆☆	This experiment demonstrates how temperature affects the volume of gas inside a balloon. By placing balloons over bottles in hot water, a refrigerator, and a freezer, students observe how gases expand when heated and contract when cooled, illustrating Charles’s Law.
Cornstarch and Water	★☆☆	★☆☆	★☆☆	This experiment uses cornstarch and water to create "oobleck," a non-Newtonian fluid that behaves like a liquid when poured but like a solid when struck or squeezed. It provides a hands-on way to explore suspensions and unusual fluid dynamics.
Diffusion in Hot and Cold Water	★☆☆	★☆☆	★☆☆	By adding food coloring to hot and cold water, students can observe that molecules in hot water move faster, causing the dye to spread more quickly.
Evaporative Cooling with Liquids	★☆☆	★☆☆	★☆☆	This activity demonstrates how evaporation causes cooling by comparing how water and rubbing alcohol feel when placed on the skin. As the liquids evaporate, they remove heat from the surface, showing how sweating helps regulate body temperature.
Hot Water Condensation	★☆☆	★☆☆	★★☆	This experiment demonstrates condensation, a key stage in the water cycle. By placing an upside-down cup with an ice cube over a cup of hot water, students can observe how water vapor cools and condenses into liquid droplets, similar to how clouds form in the atmosphere.
How Salt Affects Freezing of Water	★☆☆	★☆☆	★☆☆	This demonstration compares how quickly plain water and saltwater freeze. By observing two bowls placed in a freezer, students discover that adding salt lowers the freezing point of water, making saltwater take longer to freeze.
Ice Cube on a String	★☆☆	★☆☆	★☆☆	This simple experiment demonstrates how salt lowers the freezing point of water. By sprinkling salt on an ice cube and laying a string across it, the ice melts slightly and then refreezes, trapping the string so the ice cube can be lifted.
Melting Ice and Rising Sea Levels	★☆☆	★☆☆	★☆☆	This experiment shows the difference between melting sea ice and melting land ice. Sea ice melts without raising water levels, while land ice melting adds extra water and raises sea levels.
Melting vs Dissolving	★☆☆	★☆☆	★★☆	Compare a phase change (melting) to forming a solution (dissolving) and use simple particle models to show how the particles behave differently in each case. Students melt common solids and then dissolve sugar in water to observe that dissolving is not melting.
Mentos and Diet Coke	★☆☆	★☆☆	★★☆	Dropping Mentos candies into Diet Coke causes a rapid release of dissolved carbon dioxide, creating a dramatic soda eruption. This is a physical reaction caused by surface roughness on the Mentos that accelerates bubble formation.
Microwaving Grapes to Create Plasma	★☆☆	★★☆	★★★	When two grapes slices are microwaved while touching, the microwave energy concentrates at their point of contact, creating an intense electric field strong enough to strip electrons from atoms. This ionizes the material and produces glowing plasma inside the microwave.
Smelly Balloons	★☆☆	★☆☆	★☆☆	Students place small amounts of scented liquids inside latex balloons, inflate them, and identify the scent over time. The activity models diffusion across a barrier and introduces terms like concentration gradient, semi-permeable membrane, and equilibrium.
Viscosity With Marbles	★☆☆	★☆☆	★☆☆	Students compare how marbles fall through different liquids such as water, oil, syrup, and honey. This simple race demonstrates viscosity, or the internal friction of liquids, and helps students understand why some liquids flow faster than others.

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