Lecture Demonstrations



The following lecture demonstrations are available from Chemistry & Biochemistry Teaching Laboratories, York 3150.


Chemistry & Biochemistry Instructors may schedule the materials needed for a class by contacting Peter Wotruba by electronic mail.

A minimum of TWO (2) DAYS ADVANCED NOTICE is required.
If something not on this list is requested, more advance notice will likely be needed.


Instructions for performing the demonstrations will accompany the chemicals and glassware that are delivered to your classroom.

1. Combustion of Hydrogen

Balloons are filled with hydrogen gas, attached to a clamp holder by a string, and ignited with a match taped to a yard stick.

2. Charles' Law

Balloons are filled with oxygen and helium and show a decrease in volume when immersed in liquid nitrogen.

3. Colors of Nickel Coordination Complexes

A green, aqueous solution of nickel nitrate becomes deep blue on addition of ammonia, purple on addition of ethylene diamine, red on addition of dimethylgyloxime, finally yellow on addition of KCN.

4. Equilibrium between Nitrogen Dioxide and Dinitrogen Tetroxide, Le Chatelier's Principle

Sealed glass tubes containing reddish-brown nitrogen dioxide are placed in hot water and on dry ice and become darker brown or colorless, respectively.

5A. Colors of Cobalt Complexes

A pink, aqueous solution of cobalt(II) hexahydrate becomes dark blue when concentrated HCl is added, then pink when diluted with more water. Color projects best on an overhead projector.

5B. Colors of Cobalt Complexes in a Test Tube

A pink, aqueous solution of cobalt(II) hexahydrate becomes dark blue when heated with a torch. When the bottom of the test tube is placed in ice water, that part turns pink, while the top remains blue.

6. Ionization of Sodium Metal

A small pellet of sodium is dropped into a glass dish of phenolphthalein solution on top of an overhead projector. Red trails are produced as the sodium travels across the dish. Can do lithium and potassium to demonstrate increasing reactivity.

7. Oxidation States of Vanadium (V5+ --> V2+)

A flask containing a yellow solution of ammonium vanadate is poured into a flask containing zinc amalgam. With shaking, solution turns yellow to green to blue to purple. Vanadium can be reoxidized with cerium sulfate. Colors project well in petri dishes on an overhead projector.

8. Lecture Room Size pH Meter

An analog meter with a 30-cm scale is connected through an amplifier to a pH meter and a glass electrode.

9A. Lecture Room Size Voltmeter

A large voltmeter may be used to measure the reduction (half-cell) potentials of Zn, Cu and Pb.

9B. Lecture Room Size Voltmeter with Bologna for a Salt Bridge

An electrochemical cell is constructed from Cu and Zn half-cells and connected via a balogna salt bridge.

10. Endo- and Exothermic Reactions

Hot and cold packs are passed around the class. Students can note the temperature change.

11. Briggs-Rauscher Oscillating Reaction 

Mix equal volumes of prepared solutions on a stir plate, solution oscillates between dark blue and clear/yellow. Last about 15 minutes.

12. Hydrogen Bonding in Slime

A polyvinyl alcohol solution mixed with a sodium tetraborate solution and food coloring produces a colored polymer that flows and can be shaped; it will sheer if twisted quickly.

13. The Classic Belousov-Zhabotinsky Oscillating Reaction

Equal volumes of prepared solutions, mixed on a stir plate with ferroin indicator, give a solution that oscillates from green to violet to red to blue and back to green. Lasts about 30 minutes.

14A. A Variation of the Belousov-Zhabotinsky Oscillating Reaction

Three premeasured solutions are mixed, stirred until the bromine color disappears, and ferroin indicator is added. The solution is poured into a petri dish on an overhead projector to cover the bottom with a thin (~1-mm) layer. Oscillations will start. Refer to the March 30, 1987 issue of C&E News for the original article.

14B. Traveling waves of Color

This is another variation of the Belousov-Zhabotinsky Oscillating Reaction. It is a bit more reliable than the other variation, but it can not be premeasured and premixed.

15. Burning Magnesium in Dry Ice

Magnesium filings are pour into a cavity in a dry ice block and lit with a hand held torch. Another dry ice block with an identical cavity covers the burning magnesium. Dim the lights and the class can see the Mg burn between the dry ice blocks.

16. Light Sticks

Cyalume light sticks can be used to demonstrate how temperature affects reaction rate. Put one light stick in hot water and one in ice water. Dim lights and compare luminescence with room temperature light stick.

17. Blue Bottle Reaction

A basic glucose solution with methylene blue as a redox indicator turns blue when shaken, then reverts to clear on standing. Repeats through 15 shakes.

18. Catalytic Decomposition of Peroxide

Hydrogen peroxide is catalytically decomposed with KI. A drop of soap is added before the KI so the oxygen released during decomposition produces foam.

19. Levitation Demonstrates Superconductivity

Demonstrates the Meissner effect, where a magnet will float above a material in a super-conducting state.

20. Molecular Motion Demonstrator

Reproduces molecular behavior in gases, liquids and solids using small balls on an overhead projector. Turns abstract Kinetic Theory concepts into visual images, easily understood.

21A. Spectroscopy in Large Lecture Halls

Shows the color spectra of white light and the spectral lines of neon.  Diffraction gratings (~1in2) are passed out to the class, room lights are dimmed, and the class views light from an incandescent light and a neon discharge tube.

21C. Flame Test Demonstration of Atomic Spectra

This demonstration shows the differences of different salt solutions when burned. Cotton balls soaked with the salt solutions are burned and produce a different color flame. Diffraction gratings may be used to see the differing spectra of the salts.

22. Combustion of Acetylene

Acetylene is generated with calcium carbide and HCl and ignited with bleach. Generates an explosion with flameball.

23. Thermite

Ferric oxide and aluminum powder are ignited with an Mg fuse in clay flower pots. Molten iron drops from the pots into a dish of sand.

24. Acidity Change of Dry Ice in Water

Show acidity changes using universal indicator, dilute NaOH, and dry ice; pH changes as CO2 dissolves in water to form carbonic acid and sodium carbonate. Explain buffer solutions as the color change slows.

25. Precipitation Reactions  

One liquid is added dropwise to another, forms a precipitate. Can be done with precipitates of different colors. Views nicely on the overhead projector using large well plates, but the color of the precipatates doesn't project. Large flasks show colored precipatates well for large lecture halls.

26. Ionic vs. Covalent Bonding as Measured by Electrical Conductivity

Check solutions and solids for conductivity using an apparatus that includes an incandescent lamp and an inert gas lamp in the circuit. Salts, sugars, weak and strong acids and bases all make good materials to check. When barium hydroxide solution is titrated with sulfuric acid, barium sulfate precipatates, and the lightbulb dims and then goes out.

27. Density

Using a large container of ice water, a can of Pepsi (or Coke) sinks while a can of Diet Pepsi (or Diet Coke).

28. Boyle's Law

An apparatus for the overhead projector includes a viewable pressure gauge attached to a large syringe; allows investigation of the relationship between pressure and volume.

29. Molecular Shapes & Odors

This demonstration, generally used in the organic chemistry courses, associates shapes of molecules with odors.

30. Luminol

Two solutions mix together to produce a fluorescent yellow glow that can be seen when the room lights are off. Potassium ferricyanide crystals added to the mixture increase the intensity.

31. Carbon Snake

In this demonstration, concentrated sulfuric acid is mixed with sucrose, producing a column of carbon which grows out of the beaker.

32. Ice Bomb

Demonstrates the expansion of the water when it freeze; a cast-iron ice bomb is filled with ice water, closed, then placed in an ethanol/dry ice bath, which is then covered. Expansion of the water ruptures the bomb and causes several pieces of shrapnel to hit the cover. 

33. Nassau Reaction

This 'Halloween Demo' occurs when equal amounts of three solutions are added together. The solution turns bright orange, then suddenly turns dark blue. (Or pour half of the third solution into the mixture and wait till a nice orange color develops before adding the remainder of that solution.) Large flask with Jack-o-lantern face is available for Halloween lectures.

34. Silane

Heating silica and magnesium powder together produces silane; putting the silane compound in weak hydrochloric acid causes small fires

35. Lead Iodide Crystals

The solubility of lead iodide is about 10 times greater in hot water than in room temperature water. Dissolving lead iodide in boiling water and then letting it cool down slowly (or fast by using ice) causes the golden lead iodide crystals to form and float down to the bottom of the flask.

36. Aluminum - Copper Tradeoff

A tall graduated cylinder of green-blue copper chloride solution and a strip of aluminum react to produce changes in colors and temperature, with the formation of a solid.

37. Effects of pH on Solubility

Using a ferric nitrate solution, this demo illustrates how pH affects solubility. A precipitate forms when ammonium hydroxide is added to the test tube (when the pH reaches ~10). Then the prcipitate redissolves when hydrochloric acid is added (pH < 6).

38. Reichardt's Dye

This demo shows the dramatic affect that solvent polarity can have on absorption wavelength. In a relatively non-polar solvent such as acetone, Reichardt's dye is green; as the solvent is made more polar by the addition of water, it becomes blue, purple, magenta, red and finally orange. This can be shown quite clearly on an overhead projector.

39. Gas Creation

This demo shows how combining a liquid (dilute hydrochloric acid) and a solid (calcium carbonate) can generate a gas; a rubber stopper is placed on the test tube, and the tube is shaken to combine the liquid and powder. The resultant carbon dioxide gas causes the rubber stopper to fly about 10 feet.

40. Tyndall Effect

Using a flat-sided fish bowl and a flashlight, the effects of turbidity are shown. When only water is in the bowl, a beam of light will be virtually invisible where it passes through the bowl, and bright white where it emerges. When a thiosulfate solution is added, the turbidity increases, and the beam will be visible where it passes through the mixture. That beam will appear blue, while the light emerging from the bowl appears orange.

41. Oxidation States of Copper

This demo shows the differing colors of copper. A solution is taken from the light blue of copper sulfate, to dark blue of Cu(II)(NH3)5 complex ion, to a colorless solution of copper(I), to finally precipitating out the reddish copper metal.

42. Super-saturated Sodium Acetate Solution

A super-saturated solution of sodium acetate is made and cooled overnight. Once cooled, a tiny amount of sodium acetate is added to the solution. The entire solution then crystalizes within a few seconds.

43. Reaction of Potassium Chlorate and Sucrose

A mixture of potassium chlorate and sucrose is placed on a watchglass with a drop of sulfuric acid. This causes a reaction which starts slowly, but then bursts into flames, and creates lots of smoke.

44. Reaction of Sodium and Chlorine

Chlorine gas is generated by a combination of bleach and hydrochloric acid. This gas then reacts with sodium metal causing it to burn with a bright yellow flame.

45. Endothermic Reactions of Hydrated Barium Hydroxide

Barium hydroxide and ammonium chloride are mixed in an Erlenmeyer flask. A small wet wooden block placed on the flask will freeze to the flask.

46. Iodine Clock

Two solutions are mixed together and in a few seconds the solution turns from pale yellow to dark blue. Varying the amounts of the solutions gives diffferent times before the change occurs.

47. Demonstrating Molecular Structure with BBs

Sealed plastic petri dishes with varying numbers of BBs inside are used to demonstrate many of the microscopic differences among gases, liquids, and solids.

48. The Nonburning Towel

An ordinary cotton towel is immersed in a solution of alcohol and water and lighted over a burner. A blue flame surrounds the towel as the alcohol burns without burning the towel. 

49. Heat of Solution of Lithium Chloride

A lecture-sized temperature meter is used to show the exothermic reaction of adding lithium chloride to a beaker of water.

50. Nylon

A film of nylon is formed at the interface between two immiscible liquids. When the film is lifted from the container, it is continually replaced forming a hollow thread of polymer.

51. Dehydration of Copper Sulfate

Copper sulfate is heated on a crucible turning from the origianal blue color to white. Squirting water on the dehyrated copper sulfate turns the copper sulfate back to blue.