Hello Professors!!!
We are back from break, and these are the hottest and trendiest demonstrations for the upcoming week!
The chemicals are absolutely flying off the shelves, so order while you can!
Here is the link (Password: hydrogen) to order as well as the full list of demos; as always, early orders are very appreciated!
General Chemistry I:
Weekly topics
- Molecular Geometry and Bonding Theories
Suggested Demonstrations
Polarity and Geometry – Show the dependence of dipole-dipole forces on geometry by contrasting the effect of a charged rod on streams of H2O and “CCl4” (actually hexane) flowing from burets.
Paramagnetic O2 – Demonstrate the paramagnetism of liquid oxygen by pouring first N2(ℓ), then O2(ℓ) between the poles of a powerful magnet on the overhead projector or document camera.
VSEPR Models – Use ball-and-stick models to illustrate the VSEPR shapes and sub-shapes. Normal order is for the parent shapes. You must specify if you want subshapes
General Chemistry II:
Weekly topics
- Chemical Thermodynamics
- Periodic trends and Gases
Suggested Demonstrations
Money to Burn – Soak a dollar bill in a water-alcohol mixture and then light it with a match; the high specific heat of water keeps the combustion temperature low enough to prevent burning the bill
An Endothermic Reaction – Shake solid Ba(OH)2 8 H2O with solid NH4NO3 to produce an aqueous mixture of Ba(NO3)2 (s) and NH3 (aq). The reaction is endothermic enough to freeze the flask to a wet piece of cardboard. Alternatively, a digital thermometer can be used to record the temperature change
Thermite – Perform the thermite reaction, in which Al and Fe 2O 3 react to produce molten iron.
i) NOTE: 48 hour notice is required for this demonstration
Combustion of Ethanol Vapors – Allow a small amount of ethanol to vaporize in a large
carboy, pour out the excess liquid, and hold a lighted splint to the mouth of the container – the impressive reaction also demonstrates the explosive flammability of organic vapors
Periodic Properties – Add pieces of Li, Na, K, Mg, and Ca, to beakers of water and
phenolphthalein to observe the reactivity of metals from different parts of the periodic table. If desired, you can add HCl to those beakers where no reaction occurred
Halogens – Display flasks containing the halogens chlorine, bromine, and iodine.
i) On request, you can order a special flask of bromine that can be frozen in liquid nitrogen
General Chemistry for Engineers:
Weekly topics
- Energy & Entropy
- 2nd and 3rd law of thermodynamics
Suggested Demonstrations
Money to Burn – Soak a dollar bill in a water-alcohol mixture and then light it with a match; the high specific heat of water keeps the combustion temperature low enough to prevent burning the bill
An Endothermic Reaction – Shake solid Ba(OH)2 8 H2O with solid NH4NO3 to produce an aqueous mixture of Ba(NO3)2 (s) and NH3 (aq). The reaction is endothermic enough to freeze the flask to a wet piece of cardboard. Alternatively, a digital thermometer can be used to record the temperature change
Thermite – Perform the thermite reaction, in which Al and Fe 2O 3 react to produce molten iron.
i) NOTE: 48 hour notice is required for this demonstration
Combustion of Ethanol Vapors – Allow a small amount of ethanol to vaporize in a large
carboy, pour out the excess liquid, and hold a lighted splint to the mouth of the container – the impressive reaction also demonstrates the explosive flammability of organic vapors
Elementary Chemistry:
Weekly topics
- Gases/Liquids/Solids
- Intermolecular forces
- Solutions/Solubility
- Concentration/Dilution
- Osmosis/Diffusion
- Cell membrane
Suggested Demonstrations
Charles’ Law – Pour liquid nitrogen over a balloon to show that a decrease in T is accompanied by a decrease in V.
Like Dissolves Like – Contrast the solubility of I2 (s) and CuCl2 (s) in both water and hexane in large test tubes.
Osmotic Pressure – Small dialysis bags containing equimolar solutions of isopropanol and CaCl2 are attached to long glass tubes; immerse the bags in distilled water to illustrate osmosis and to show that osmotic pressure depends on the number of particles in solution.
Polarity and Solubility – Add acetone to a saturated solution of CuSO4 (aq) causing CuSO4 (s) to crystallize out – the solubility of CuSO4 decreases as the polarity of the solvent is decreased.
Ammonia Fountain – Show the solubility of NH3 (g) in H2O due to hydrogen-bonding.
Boiling Water at Room Temperature – Show water boiling at room temperature in a beaker in an evacuated bell jar, then put your hand in the water after boiling to convince students of its low temperature.
Foundations of General Chemistry:
Weekly topics
- Ideal/real gas law
- Mixtures & partial pressures
- Effusion/diffusion
Suggested Demonstrations
Charles’ Law – Pour liquid nitrogen over a balloon to show that a decrease in T is accompanied by a decrease in V.
Graham’s Law of Diffusion – Allow concentrated NH3 and concentrated HCl to vaporize and meet in a horizontal glass tube, forming a ring of NH4Cl.
Marshmallow Snowman – Demonstrate the effect a decrease in P has on V by placing a marshmallow snowman in a bell jar and then evacuate the jar.
Squashing Pop Cans with Atmospheric Pressure – Use atmospheric pressure to squash pop cans.
Thank you and have a great week!
–The Demo Lab
PS if you are ahead/behind of schedule let us know so we can adjust the demos accordingly. Currently we are simply using the syllabi to guess where your respective classes are at. And here is the link again 🙂: Demo Ordering Link