Change of State Topic

PVT Surfaces

Concept 2 demos

3D PVT surface model with color-coded phase regions: black for Solid, yellow for Liquid and two-phase regions (Liquid & Vapor, Solid & Vapor), and red for Gas and Vapor, with labeled axes for Pressure, Volume, and Temperature

PVT Surface

A 3D model shows how pressure, volume, and temperature are interrelated for a real substance, with labeled phase regions (solid, liquid, gas) and coexistence surfaces. Students visualize how familiar 2D …

Composite of four photos: top-left shows the PVT demonstrator with fiber optic lamp and projection lens on a demo bench; middle-left shows the projected image of the pressure gauge and bimetallic thermometer on a screen; bottom-left shows a closer view of the piston-cylinder apparatus with crank handle; right shows a detail of the pressure chamber with gauge and valves

PVT Demonstrator

A piston-cylinder apparatus with projected pressure and temperature gauges demonstrates the relationship between pressure, volume, and temperature in a gas. Students observe pressure and temperature rise during compression, cooling at …

Phase Changes: Liquid-Solid

Concept 2 demos

Cast iron ice bomb: a spherical vessel with a threaded cap connected by a curved pipe to a rectangular metal block, shown before freezing

Ice Bomb

Water sealed in a heavy-walled metal container freezes and expands (~9% by volume), generating enough pressure to rupture the container. Students see dramatic evidence of water's anomalous expansion upon solidification …

Three views of the ice fountain apparatus: top shows the hydraulic jack with pressure gauge, central cylinder, and conical nozzle on a demo bench with tools; bottom-left shows the outer cylinder filled with crushed ice and the nozzle visible at top; bottom-right shows an extruded ice cylinder emerging from the nozzle

Ice Fountain

Crushed ice is forced through a conical nozzle by a hydraulic jack. The pressure melts the ice, and it refreezes into a solid cylinder as it exits the nozzle — …

Phase Changes: Liquid-Gas

Concept 1 demo

Three views of the critical point apparatus: optical bench with arc lamp and condensing lenses (top left), boiler with pump motor and Ratiotrol control box (top right), and complete setup showing mirror, projection lens, Freon cell, and fluid circulation system (bottom)

Change of Phase

Students observe the liquid-gas phase transition at the critical point of Freon-115 , witnessing critical opalescence and the disappearance of the meniscus as the distinction between liquid and gas vanishes. …

Cooling by Evaporation

Concept 3 demos

Cryophorus: a glass apparatus with two spherical bulbs connected by a long glass tube, lying on a tabletop in front of a chalkboard

Cryophorus

Water freezes inside a partially evacuated glass bulb solely through evaporative cooling -- the dry-ice-cooled second bulb acts as a cold trap that continuously removes water vapor, driving rapid evaporation …

Three-panel photo: top shows overhead projector on movable bench with vacuum pump below; bottom-left shows vacuum chamber apparatus with magnifying lens on projector stage; bottom-right shows close-up of concave lens, cover glass, and eyedropper

Freezing by Boiling

Water boils and then freezes under reduced pressure in a projected vacuum chamber. Demonstrates that boiling point is pressure-dependent and that rapid evaporation removes enough latent heat to freeze the …

Drinking bird mid-cycle, captured with motion blur showing its rocking oscillation, on a clear acrylic tray with an empty glass beaker beside it

Drinking Bird

Evaporative cooling of the bird's wet head lowers the vapor pressure of the ether inside, drawing liquid up into the head and shifting the center of mass until the bird …

Dew Point and Humidity

Concept 2 demos

Sling psychrometer with two parallel glass thermometers mounted on a wooden board, with a wire sling handle at one end and a cylindrical brass counterweight at the other. A beaker of water sits nearby.

Wet and Dry Bulb Hygrometer

A sling psychrometer measures relative humidity by comparing wet and dry bulb temperatures. The wet bulb depression depends on evaporation rate, which depends on ambient humidity -- connecting evaporative cooling …

Large clear container of water, crushed soda can, intact soda can on a tripod, propane torch, and heat-resistant gloves

Condensation in an Aluminum Can

Demonstrates the enormous magnitude of atmospheric pressure. Rapid condensation of steam creates a near-vacuum inside an aluminum can, and the resulting pressure differential crushes it with a loud bang. Also …

Vapor Pressure

Concept 2 demos

Top of pressure cooker showing pressure gauge (0-30 psi), ball valve with lever mechanism, and thermocouple wire exiting through the lid

Pressure Cooker

Shows that the boiling point of water depends on pressure. A differential thermocouple compares the temperature of boiling water at atmospheric pressure with water in a sealed pressure cooker, demonstrating …

Pulse glass at rest: hand-blown glass with two bulbs connected by a narrow stem with decorative loops, purple liquid pooled in the lower bulb

Pulse Glass

Demonstrates the temperature dependence of vapor pressure. A sealed glass tube contains methyl chloride; body heat from your hand increases the vapor pressure in the lower bulb enough to force …

Sublimation

Concept 1 demo

Block of white dry ice resting on an insulated fabric glove with a metal teaspoon on top and a second small spoon with a white handle beside it

Sublimation

Shows sublimation of dry ice (solid CO2 directly to gas) with two effects: the block hovers on a gas cushion across the table, and a metal spoon pressed against it …

Phase Changes: Solid-Solid

Concept 1 demo

Iron Wire Expansion

Demonstrates thermal expansion and a solid-solid phase transition in iron. A current-heated wire sags as it expands, then visibly contracts when iron transforms from BCC (α-iron) to FCC (γ-iron) at …

Critical Point

Concept 1 demo

Trans-Sonics Equiphase triple point cell: polished stainless steel cylinder with glass reentrant thermometer well protruding from the top, and blue plastic protective cap shown beside it

Triple Point Cell

Students observe all three phases of water coexisting in thermodynamic equilibrium at the triple point (273.16 K, 611.657 Pa). Connects phase diagrams to physical reality and demonstrates the Gibbs phase …