Hello Professors!!!
Today is Thursday, February 29th…
With spring break almost upon us, we recommend treating your students to one of our particularly exciting demonstrations to “burn” the concepts in their mind before the break. These include:
Thermite
Potassium permanganate/glycerin
Combustion of magnesium in dry ice
H2/O2 Balloon series
Or any of our other Fire Friday Demos
…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 –Basic Concepts of Chemical Bonding
Suggested Demonstrations
Contrast models of NH2—NH2, NH=NH, and N≡N to show the decreasing N–N bond length as the bond order increases
General Chemistry II:
Weekly topics
-Mechanisms and Catalysis
-Additional Aspects of Aqueous equilibria
Suggested Demonstrations
Catalysis of a Reaction – Demonstrate the catalysis of the H2O 2 decomposition of NaK-
tartrate with Co 2+. Adding Co 2+ turns the solution pink, but the solution quickly turns dark green as it begins to react vigorously. At the end of the reaction, the pink color is restored showing regeneration of the catalyst
Elephant Toothpaste – Demonstrate the decomposition of 30% H2O 2 in the presence of
dishwashing liquid and KI, producing an upsurge of steaming foam
Iodine Clock Reaction – Perform the iodine clock reaction with three different initial concentrations of IO3–
Catalysis of a Reaction – Demonstrate the catalysis of the H2O2 decomposition of NaK-tartrate with Co2+. Adding Co2+ turns the solution pink, but the solution quickly turns dark green as it begins to react vigorously. At the end of the reaction, the pink color is restored showing regeneration of the catalyst
Briggs-Rauscher Oscillating Reaction – Introduce the mystery of mechanisms with the Briggs-Rauscher Oscillating Reaction.
Buffer Capacity Demo – Contrast the buffer capacity of water, 1 M CH3COOH/NaCH3COO, and 0.1 M CH3COOH/NaCH3COO by adding increments of 6 M HCl to each in the presence of an indicator
Common Ion Effect Demos HCl/NaCl – add concentrated HCl (aq) to saturated NaCl(aq) to cause precipitation of NaCl (s)
General Chemistry for Engineers:
Weekly topics
-Energy and Chemistry
Suggested Demonstrations
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.
Glycerin and Potassium Permanganate – Pour glycerin over KMnO 4 (s) to initiate a
spontaneous combustion accompanied by smoke, sparks, and a lavender flame.
Elementary Chemistry:
Weekly topics
-Gases and IMFs
Suggested Demonstrations
Lake Nyos Demo – Pour CO 2 (g) down an enclosed set of steps to extinguish candles
on each step, demonstrating the fluidity of gases, and recreating (on a small scale) a
tragic natural disaster
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
Use pairs of space-filling models of n-pentane and isopentane to show that increased
branching increases compactness, decreases polarizability, and decreases London forces
- i) Pair with velcro models to simulate the strength of IMF between branched and un-
branched hydrocarbons
Foundations of General Chemistry:
Weekly topics
– Thermochemistry
Suggested Demonstrations
Hot and Cold Packs – Combine NH4NO3 (s) and water in a Ziploc bag to make an instant “cold pack”. Combine CaCl2(s) and water to make an instant “hot pack”
Thermite – Perform the thermite reaction, in which Al and Fe 2O 3 react to produce molten iron.
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
Thionine Reaction – Hold a solution of thionine and FeSO4 in front of a bright light to show the reduction of thionine from a violet form to a colorless form; this is an endothermic reaction that absorbs light energy.
Luminol – Pour solutions of luminol and H2O2 into a tall glass spiral to produce a beautiful chemiluminescent reaction. The light-emitting species is the dicarboxylate ion, aminophthalate, the product of the oxidation of luminol with H2O2
Combustion of Candy – Contrast the oxidation of sucrose in the body (by eating some candy) with the oxidation of sucrose by KClO3 (as shown by dropping some candy into molten KClO3, producing steam and a lavender flame. The body temperature is ~37°C, and the melting point of KClO3 is 368°C.
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
Kind regards,
Lynda Reynolds