Computerized chemical laboratory works

O.A. Povalyaev - Chief of the "SNARK" research group, candidate of technical sciences
N.A. Reztsova - Scientist of MITHT of M.V. Lomonosov's name

The "SNARK" research group of new training technology laboratory at Moscow car-maker institute (MASI) has been functioning over a year. One of the most interesting and perspective works of the group is a creation of L-micro ® educational computer laboratory complex for a secondary school. However, a real work of the complex creation started much earlier. The attention of laboratory has been in last years drawn to secondary school computerization and making of the modern school labware problems. There are some exhibitions in which laboratory exhibits participated: "The World of childhood '94", "Education '94", "Education '95", "Сomtek-96", "UNESCO - 96". L-micro ® computer complex recommended by the Ministry of Education of Russia for using in high schools and designed by the "SNARK" group together with the Moscow professional development institute for educational employees (MIPKRO). "Chemistry" section is one of three L-micro ® sections, including also "Physics" and "Biology" sections. Detailed L-micro ® publications about practical physics works are placed in "Physics at school" magazine (1996, pp. 75-79) and in the "Information problems of the higher school" bulletin (1995). The "Chemistry" section designed first and now tens of Russian schools actively use it. The "Chemistry" section is created on the basis of development experience of computer practical physics works and in view of chemistry subject properties. The chemistry takes the key place in natural sciences and it is the base at biological systems and ecology problems studying. An important role of chemistry in formation of natural-science outlook and general culture of a person is caused by an opportunity with the help of chemistry to show intersubject ties, integration of natural sciences. At making a series of L-micro ® practical works authors took into account that chemistry promotes formation of intuitive, figurative, "chemical" thinking as against physics and mathematics, directed first of all at logic thinking. Therefore at studying chemistry at school the practical works have especial importance. Only mastering of actual, "real" experiment and getting experimental skills can develop such thinking. The interested chemistry studying is mainly possible by the wide application of laboratory works at educational process. However, the number of demonstration and especially practical works used in secondary school is really insignificant. To carry out such lessons more difficult, than a usual. Experiment preparation and exercising require a considerable time and material costs and also observance of security measures. On the other hand, the school equipment of a chemistry class has not subjected to essential changes. Frequently, such equipment does not satisfy modern school needs it is expensive enough. Now between a series of the modern powerful methods of the experimental chemistry and school chemistry practical works the severance lies. To provide continuity between school knowledge and the modern methods of practical chemistry, it is necessary to use even elementary of them at educational practical work. L-micro ® laboratory computer complex meant for help the teacher to overcome the specified difficulties, to carry out even a part of practical works at the modern level and to raise chemistry appeal. The modern chemistry research techniques have huge opportunities first of all in the field of a chemical analysis, and also in process control. It became possible due to combination of chemical process with physical measuring methods on the one hand, and with the computer, providing gathering, data processing and process control systems on the other hand. Developers of the new chemistry laboratory complex started with the same principle (chemical process + physical measuring method + computer). The modern personal computer used as the universal computer. The computer can write, save and process the received experimental data, it can present information at any forms: as a diagram or as a table. If there is a printer it can print out a work results. The data of especially successful or unexpected experiments can gradually accumulated in a computer memory and make the fund at the disposal of a teacher. Except for "Carrying out of experiment" and "Data processing" items, each practical work contains also "Theory", "Tolerance" and "Protection" items. Thus, programmers of the "SNARK" group extremely simple computer control programs accessible both for a teacher, and for a pupil are created. It is especially important for practical chemistry works that record of any chemical response parameters makes in the continuous mode. An experimenter at any moment has the operative information on a process progress, not distracting for toilful data recording or calculations. Often, a computer displays the kinetic curve. Depending on a pupil skill, not only numerical value of the explored parameter, but also observation over process dynamics: rate, response changes can be work result. A minimum time used for carrying out of the experiments, because at the continuous mode of data recording there is a particular criterion of end resulting, for example, curve output to the constant value. The kinetic curve is acknowledgement of received result reliability. Besides the opportunity to compare substance properties by qualitative and quantitative values has appeared. The majority of equipment measuring parts (sensors) designed by the "SNARK" research group. Temperature, pressure, рН and conductivity sensors are still chosen for use in the "Chemistry" complex. High sensitivity of these sensors allows to file even a very low signals and "to see" those processes which cannot be registered with the help of traditional approaches to a school experiments. The important advantage of the specified sensors application is an opportunity to use the minimum quantity of substances. It became possible not only due to a high sensitivity, but also to a compactness of these sensors, which are submerged in a substance. As to a chemical reactors, i.e. that part of equipment which pupils can self-maintainedly assemble and can connect to a measuring system, the main principles of developers for them were: presentation, availability and safety.

Devices are very simple, they can be assembled easily both by a teacher and pupils. To approach practical works at school to normal laboratory works, the part of equipment, in which chemical process comes, is completed with traditional glass chemical ware. It is, for example, a chemical graduated glassful with the agitator (fig. 1) or a test tube with a glass nozzle, hermetically associated with the help of standard socket-cable (fig. 2). Such equipment is universal; the same device used not only at several experiments, but also at various practical works. At desire, its separate parts can be exchanged by similar, available in laboratory. Using these devices a researcher simultaneously observes process "from inside" with the help of the sensor and visually if there are changes of reactionary mass visible by an eye. For example, it is possible to correlate sensor indications with dissolution of substance or color changing of a solution. The majority of works does not represent any danger because the computer at schools placed not in chemistry classrooms, but in computer classrooms. The accessible and inexpensive harmless substances are used at carrying out of a significant number of experiments. Besides for chemical agent saving it is possible to lead multilateral research of one process by connecting various sensors to the same reactionary medium. At planning examinations the "SNARK" research group took into account that there is no necessity to use any measuring instruments for carrying out of a significant number of chemistry experiments. Under the principle of computer application expediency the following practical computer works designed: thermal effect at substance dissolution, thermal effect of chemical responses, studying of an electrical conductance of water solutions, determination of рН, determination of water hardness, response rate relation from various factors. The practical work based on a definition of the optical rotation angle of substance solution, is a part of the "Physics" ("Work principles of polarimeter") and the "Biology" sections ("Optical properties of carbohydrates"). Meanwhile, this work can be included in the "Chemistry" section as an explanation of light polarization by optically active substance is possible only in the chemistry subject course. Let's stop on some interesting features of chemistry practical works. The size of a zinc granule, necessary for examination of chemical response rate, makes only 1-2 mm! The common granule in some grams is enough for carrying out of practical work by the whole class. And it is enough a one milliliter of 10% solutions of a hydrochloric acid to carry out three comparative experiments for 10-15 minutes! Data processing under the program takes some minutes and pupils gain three kinetic curves disposed on one diagram and relevant chemical response rates. Thus, device assembly, measuring system connection, substance preparation and their mixture and preparation for the next experiments can be carried out both by a teacher and pupils. Research results of the thermal effects were unexpected even for complex developers. Only due to device using the self-checking opportunity has appeared at carrying out of an experiment. For example, it is possible to estimate, as far as uniformly and accurately the experimenter adds substance and makes intermixing. The temperature "jump" relevant to solution overheating at interfusing of some substances looks very effectively. At performance of the "Studying of an electrical conductance of water solutions" practical work the substance microquantities (on a spatula's tip) are used. Pupils observe substance dissolution, after its complete dissolution gain the value of electrical conductance of the dilute solution and classify substances on nonelectrolytes, strong electrolytes, half-strong electrolytes and weak electrolytes. The sensor allows to compare water quality from various sources even from a cold and hot water pipelines. We hope, that L-micro ® computer educational complex due to the modern research approach will help a teacher to interest pupils and to raise the chemical educational prestige.