How to Do the Barking Dog Chemistry Demonstration

How to Do the Barking Dog Chemistry Demonstration The Barking Dog chemistry demonstration is based on an exothermic reaction between nitrous oxide or nitrogen monoxide and carbon disulfide. Ignition of the mixture in a long tube results in a bright blue chemiluminescent flash, accompanied by a characteristic barking or woofing sound. Materials for the Barking Dog Demonstration Stoppered glass tube containing N2O (nitrous oxide) or NO (nitrogen monoxide or nitric oxide). You can prepare and collect nitrous oxide or nitrogen monoxide yourself.CS2, carbon disulfideLighter or match How to Perform the Barking Dog Demonstration Unstopper the tube of nitrous oxide or nitrogen monoxide to add a few drops of carbon disulfide.Immediately re-stopper the container.Swirl the contents around to mix the nitrogen compound and carbon disulfide.Light a match or lighter. Unstopper the tube and ignite the mixture. You can throw a lit match into the tube or use a long-handled lighter.The flame front will move rapidly, creating a bright blue chemiluminescent flash and a barking or woofing sound. You can re-light the mixture a few times. After the demonstration is performed, you can see sulfur coating the inside of the glass tube. Safety Information This demonstration should be prepared and performed inside a fume hood by a person wearing safety goggles. Carbon disulfide is toxic and has a low flash point. What Is Happening in the Barking Dog Demonstration? When the nitrogen monoxide or nitrous oxide is mixed with carbon disulfide and ignited, a combustion wave travels down the tube. If the tube is long enough you can follow the progression of the wave. The gas ahead of the wavefront is compressed and explodes at a distance determined by the length of the tube (which is why when you re-ignite the mixture, the barking sounds in harmonics). The bright blue light that accompanies the reaction is one of the few examples of a chemiluminescent reaction that occurs in the gas phase. The exothermic decomposition reaction between nitrogen monoxide (oxidizer) and carbon disulfide (fuel) forms nitrogen, carbon monoxide, carbon dioxide, sulfur dioxide and elemental sulfur. 3 NO CS2 → 3/2 N2 CO SO2 1/8 S8 4 NO CS2 → 2 N2 CO2 SO2 1/8 S8 Notes about the Barking Dog Reaction This reaction was performed by Justus von Liebig in 1853 using nitrogen monoxide and carbon disulfide. The demonstration was so well-received that Liebig performed it a second time, although this time there was an explosion (Queen Therese of Bavaria received a minor wound on the cheek). Its possible the nitrogen monoxide in the second demonstration was contaminated with oxygen, to form nitrogen dioxide. There is also a safer alternative to this project that you can do with or without a lab.

Portfoilio week 8 6310 Essay Example | Topics and Well Written Essays - 500 words

Portfoilio week 8 6310 - Essay Example The demonstrations will be on the oral methods of drug administration to different types of patients depending on their ages, conditions and instructions from the doctor. In line with this, i will divide the class into several teams of two people each and then using the simulation dummies (where I will have attached notes on each â€Å"patient† to be administered drug to), I will monitor and evaluate on how each team performs its instructions (based on what I have taught in class) and then grade them (Billings and Halstead, 2012). According to Svinicki and McKeachie, (2011), demonstration is an effective and useful method to evaluate the learning of students where the main aim of the lesson is practicality. The objectives of this lesson are: Students will identify different methods of imparting positive attitude to the patients during the drug administration. This first objective on a higher level taxonomy yields two objectives which are: students will select the best method to use to impart positive attitude to the patients during drug administration. The second one is: students will apply this selected method when administering drugs to the patients. How are the learners able to identify the different ways of imparting positive attitude during drug administration? How are they able to select the best of these methods and applying them? The other objective is: the students to list the different ways of administering oral medication according to the patient’s condition, age and doctors’ instructions. On a higher level taxonomy (http://www.nwlink.com/~donclark/hrd/bloom.html), this objective has two other objectives which are: the students to select the most effective ways to administer drugs according to the patient’s condition and doctor’s instructions and the other is for the students to be able to apply the most effective ways of administering oral medication according to the patient’s condition,