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Post Time:2012-7-31 9:40:00
Chemistry is a laboratory-based disciplines, success of the experiment, and obvious phenomena have a direct impact on students understand and master the knowledge at the same time, experimental teaching is an important part to improve the quality of teaching to strengthen the reform of the experimental teaching is the key of the experimental teaching.
5.1 of cleaner fuels - hydrogen "section of the new textbooks are now several improvements experiments described below:
An experimental improvements
An experimental preparation: Hydrogen generator, oxygen generator, glass tubes, rubber tubes, beakers, flat (household detergent (household.
Improved experimental operation:
(Blowing a soap bubble experiment:
Conduit opening by a short rubber tube (generally do not need the hydrogen dry, dipped in detergent solution (instead of liquid soap with hydrogen blowing, bubble blowing is large enough, gently shaking the airway, so that bubbles out of the nozzle, the bubble rise.
(2) hydrogen burning in the air:
Option One: flat, dump some detergent solution, pure hydrogen stream blowing, and then use long strips of wood burning in the ignition, observed the phenomenon of hydrogen burning.
Option II: In order to avoid the sodium ions interfere with the hydrogen flame color with copper beak catheter instead of glass tubes, so that you can see a light blue flame of hydrogen burning, Furthermore, this phenomenon hydrogen combustion releases heat, difficult for students to realize we can be a match with petroleum jelly and dipped in a beaker bottom, and will cover the beaker above the flame, the combustion heat release Vaseline melted down vertical matches, so that both image and intuitive.
(3 hydrogen and air mixture explosion experiments:
Flat, dump some detergent solution, hydrogen gas stream blowing at the same time, syringe pumping air or oxygen flow, followed by blowing bubbles (hydrogen volume fraction of control in between 0.4-7.42, and then use long strips of wood burning fire, heard a sharp burst song, that impure hydrogen gas light may explode.
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(4 in the lectures of the explosion limit of hydrogen, in the actual teaching, I am so done:
First dump some detergent liquid hydrogen stream blowing at the same time in the flat plate, with a syringe pumping air or oxygen flow followed by blowing bubbles (hydrogen volume fraction is controlled at below 0.4, then use long strips of wood burning fire, to listen to to a slight "pop" sound, no explosion, and then repeat the previous operation (hydrogen volume fraction in 7.42 above, the same phenomenon appears, leads to the concept of the explosion limit. (Hydrogen volume fraction is controlled at below 0.
4, or 7.42
(Five hydrogen pure experience: first dump some detergent solution in the flat plate, blowing bubbles with hydrogen stream, and then with long strips of wood burning in the ignition, I heard a sharp explosion song to prove that hydrogen impure if hear a slight "pop" sound to prove that has pure hydrogen.
Second, improve the advantages of
1 instruments less a flat ignite hydrogen, blasting and experimental explosion limit of hydrogen experience pure operation, easy to operate, the experimental phenomena.
2 in the experimental procedure using detergent liquid alternative to soap, make bubbles blown large enough, and the toughness and difficult to break, is the key to the success of experiments.
Combustion, explosion occurred in the detergent vacuoles, to overcome the danger of ignited hydrogen, eliminating the teachers, the students' psychological sense of insecurity, so the students can boldly to participate in inquiry activities. Students from local materials, use side objects ability to do the experiment.
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