Hello Professors! 

Today is Friday, March 29th, 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 

• Gas laws 
• Pressure/Partial Pressure 
• Effusion/Diffusion 

 

Suggested Demonstrations 

• Squashing Pop Cans with Atmospheric Pressure – use atmospheric pressure to squash pop cans 
• 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 
• 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. (Upon request, we can give you a clean beaker and tap water if you want to drink the boiled water) 
• Vanilla Balloons – Pass around a few balloons containing a potent osmophore (vanilla) and ask students to identify the odor; the odor is detectable because of the diffusion of vanillin molecules through pores in the balloon. 

• Charles’ Law – Pour liquid nitrogen over a balloon to show that a decrease in T is accompanied by a decrease in V. 

 

General Chemistry II:  

Weekly topics  

• Electrochemistry 
• Redox reactions 
• Voltaic cells 
• Electrolysis 

 

Suggested Demonstrations  

• Metal Redox Reactions – Compare redox reactions between metals and metal ions to see which is spontaneous 
• Multiple Oxidation States of Manganese – Starting with KMnO4(aq) in four beakers, carry out reactions to display manganese in the +7, +4, +3, and +2 oxidation states 
• Copper/Zinc Voltaic Cell – Demonstrate a copper/zinc voltaic cell turning a motor to show that a spontaneous reaction can be harnessed to do work. 
• Electrolysis of Water – Electrolyze water (dilute Na2SO4 solution with indicator) in the Hoffman apparatus to decompose it into its component elements, hydrogen and oxygen. If desired, you can test the H2 (g) and/or O2 (g) produced with a flame and a glowing splint, respectively. 

 

General Chemistry for Engineers:  

Weekly topics  

• Equilibrium 
• Solubility 
• Le Chatelier’s Principle 
• Acids & Bases

 

Suggested Demonstrations  

• Le Chatelier’s Principle: Iron(III) Thiocyanate Equilibria – Apply stress to the Fe3+ + SCN- → FeSCN2+ system in five different ways to show the equilibrium shifts accompanying changes in the concentration of reactants 
• Cobalt Complexes and Temperature v2.0 – Demonstrate effects of concentration and temperature changes on the Co(H2O)62+/CoCl42– equilibrium 
• Effect of Temperature on NO2 ↔ N2O4 Equilibrium – Immerse sealed tubes of NO2/N2O4 in hot and cold water to show how temperature shifts the equilibrium position and to show the reversibility of the shift; red-brown NO2 predominates at high temperatures and colorless N2O4 at lower temperatures 
• Acid-Base Titration – Add 1 M NaOH (aq) to a solution of 0.1 M HCl and phenolphthalein to show the endpoint. 

 

Elementary Chemistry:  

Weekly topics  

• Strong acids/bases 
• Weak acids/bases 
• Buffers 

 

Suggested Demonstrations  

• Acids and Bases – Add drops of 0.1 M NaOH to a magnetically stirred solution of water and universal indicator until it turns blue, then add drops of 0.1 M HCl until the solution turns orange. 
• Strong and Weak Acids and Bases – Use two conductivity testers with light bulbs to contrast the conductivity of weak and strong electrolytes: acetic acid and HCl (aq), and/or NH3 (aq) and NaOH (aq) 
• Acid-Base Titration – Add NaOH (aq) to a solution of HCl and phenolphthalein to show the endpoint. 
• Acidic and Basic Oxides – Dissolve several oxides (CaO, ZnO, CO2, P4O10) in water containing universal indicator to show a range of basic and acidic oxides 
• Yamada and Breath – Have a student wearing a white or light-colored shirt use a straw to blow into water containing Yamada universal indicator or to observe the color change accompanying the reaction 

 

 Foundations of General Chemistry:  

Weekly topics  

• Solids/Liquids/Gases 
• Intermolecular Forces 
• Vaporization/Sublimation 
• Vapor Pressure 
• Phase Diagrams 

 

Suggested Demonstrations  

• Dry Ice Sublimation – Make the sublimation of dry ice “visible” by dropping a piece of dry ice in a beaker of water. (Optional: place a piece of dry ice in a glove, tie it off, and allow the dry ice to sublime, inflating the glove.) 
• Changes of state – Pour liquid nitrogen into a beaker to demonstrate a variety of phase changes: the boiling of N2(ℓ), the deposition of H2O(g) as H2O(s) on the outside of the beaker, and the melting of H2O(s) to H2O(ℓ) as the beaker eventually warms up again 
• 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 flammability of organic vapors. 
• 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. (Upon request, we can give you a clean beaker and tap water if you want to drink the boiled water) 
• Triple Point of CO2 – Demonstrate the existence of three phases of CO2 at the triple point by adding crushed dry ice to a clear acrylic tube fitted with a pressure gauge and a release valve 

 

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