A FRESHMAN COURSE IN CHEMISTRY IN AN ENGINEERING COLLEGE* LEONS. WARD.COLORADO SCHOOL OB MINES,GOLDEN, COMRADO
Many engineering schools require a year of high-school chemistry for entrance and also emphasize the study of chemistry in the training given their men. The course as here outlined is based upon giving general chemistry and qualitative analysis as thefirst year's work. To accomplish this, emphasis i s placed on the theoretical phases of the subject enrly in the course. Qualitative analysis and the study of the metals and their compounds constitutes the work for the second semester. The usual dificulties met with when such a n arrangement i s pnrsued have been modified by approaching palitatinre analysis from a different angle than that usually chosen.
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To shape a given course so that it shall be of most value to those taking the work is the aim of every teacher. I n a liberal arts college where the class is composed of individuals looking forward to many different lines of work the chemistry course is quite varied in subject matter and in methods of attack. The so-called "pandemic" chemistry serves the purpose where the class is definitely not going into scientific work. In an engineering school, however, we deal with boys who have already chosen a general line of work. Here it is possible to shape the course to the needs of the group in a very helpful way and to accomplish more in the same length of time. Many of the engineering schools are now requiring for entrance highschool credits in chemistry, in physics, and in mathematics through solid geometry. This should bring to such institutions a group of boys whose interests are along mathematical and scientific lines. Since they all have had work in chemistry there should he some elementary chemical knowledge on which the college course could he built, the possession of which would lighten somewhat the work of the freshman year. By means of a placement examination in chemistry given the first week of school and by a study of the grades made in quizzes throughout the year we have sought t o determine what concepts and actual abilities the entering freshman has brought with him. The conclusion we have reached is that although a few come with an excellent foundation most of them have very little on which a college course can be built. This means, then, that unless some system of grouping can be worked out, the first year's course must take a somewhat middle ground and, while mentioning practically every elementary principle, must pass quickly over some and require the student to look them up more completely outside of class. What do we expect to accomplish with these men during their freshman year? It is an accepted principle that an engineer must have a thorough scientific and mathematical foundation and every engineering school of * Presented before the Division of Chemical Education at the 81st meeting of the A. C. S. at Indianapolis. Indiana, March 31, 1931. 1824
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standing requires all its men to take a year of general chemistry. When the fields of engineering in which the school is interested are further restricted, as a t the Colorado School of Mines, to the four fields dealing with the mineral industriesmetallurgy, mining, petroleum, and geology--a thorough training in chemistry becomes even more important. While no degree in chemical engineering is definitely offered yet a man taking a degree in metallurgy or in petroleum refining must have chemical training almost equivalent to that required of the chemical engineer. Besides the freshman work, courses in quantitative analysis, physical chemistry, and, for some, organic chemistry are required and many specialized courses in the various options are waiting to be given when this foundation in chemistry is completed. The first-year chemistry course, therefore, becomes equal in importance to any other course in the school. To further complicate matters, the curriculum is so crowded that qualitative analysis cannot be postponed to the second year, as is often done, but must be included in the first year's work if it is to be presented at all. Accepting the freshman, then, as he comes to us with his smattering of chemical knowledge, we are expected in a year's time to lay such a foundation in general chemistry and qualitative analysis that he can build on it advanced courses in chemistry and allied subjects. In accomplishing this we have found it necessary to reduce to a minimum any discussion of descriptive and historical aspects of the subject, devoting the time, instead, to fundamental chemical principles. Also, we found that we must devote more time to the study of the metallic elements than is allowed in many courses. The boys we work with are looking forward to employment in the mineral industries and need to know all we can teach them regarding the metals. Finally, as we all know, repetition a t intervals of time plays an important part in the learning process. If a topic can he presented early in the course and then made use of as the work proceeds the student becomes familiar with the concept and it becomes a tool which he can use. These three principles have been the ones we have had in mind as we have planned the course. Chemistry presents two principal lines of study-the constitution of matter and its behavior. We start with the study of the structure of substances as expressed in the molecular, atomic, and electronic theories. We feel that the molecule and the atom should be somewhat familiar units to the freshman, while the electronic concept will advance him into new and interesting fields. All too frequently, however, we find the boy unable to derive any significance from a formula such as H20, either in terms of atoms and molecules, or in terms of weights concerned. The arrangement of the elements in the periodic table is introduced as a systematic grouping based on structure and properties. The history is practically omitted and the table presented as a chart to be used constantly, the in-
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telligent reading of which constitutes one of the objectives of the year's work. The gaseous, liquid, and solid states of matter are surveyed, followed by a study of solutions and of colloids presented as mixtures of substances differing primarily in degree of dispersion. Before ionization is taken up a general discussion of acids, bases, and salts as three classes of compounds is given. Then the ionized condition is discussed, more from the modern angle than from the historical viewpoint. Having treated the subject of the structure of matter we next turn to the study of its behavior. This involves the examination of the chemical reaction. We spend considerable time on this topic studying the various types of reactions, the characteristics, the quantitative relationships, the energy changes involved, its reversibility and the methods of controlling the resultant equilibrium. Reactions are examined from the standpoint of any shift of electrons which may take place. Oxidation and reduction have been treated from the first as involving such electron shift or valence change. Emphasis is placed throughout on developing the ability to predict, with reasonable accuracy, the products which will be formed. The electromotive series of the metals is constantly used as a means of predicting probable reactions and the stabilities of certain classes of compounds. As the close of the semester approaches we turn to the study of the nonmetals and their compounds. We use the long form of the periodic table and take the group as the basis of study. The similarities and the dissimilarities in atomic structure are brought out and the chemical conduct of the free elements is correlated with this structure. The compounds formed with hydrogen are first studied as typical hydro acids and then the compounds with oxygen are taken up. This is followed by a survey of the compounds formed when the oxide combines with water. These oxy acids are treated both as hydrated oxides and as hydroxides of non-metals. The former treatment is especially important with our men, since so many of their geological formulas are written in oxide form. The acid radical is treated as the group which sets one particular acid apart from others. This radical is then followed into the salts formed from the acid and its stability and general behavior in such compounds is noted. The emphasis a t this stage is placed on the behavior of the salts as a group of compounds related to a given acid. The study of important individual salts is postponed to be taken up in connection with the study of the metal constituents. Since our men all take work in geology and mineralogy we also find it helpful to spend some time on the topic of the condensation of simple acids into the more complex types by removal of water. The acids of silicon are used as the class material for this. If time permits we spend about a week on the compounds of carbon a t this point. If not noted here, i t is generally put off until the last part of
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the second semester's work. Our petroleum men will later take a semester course in organic but with the others the freshman course is the only time they receive instruction in such work. The laboratory work of the first semester is confined to one three-hour period per week. It is planned to he different from the high-school course and to be quantitative in character wherever possible. The regular analytical balances used by our sophomores in quantitative analysis are available and the freshmen become familiar with them. This is helpful the next year. When the study of the non-metals is taken up in class as outlined above, the laboratory work is devoted to a more qualitative study of the reactions of these elements. This is planned to lead into the study of the anions, with which we open the qualitative worli of the second semester. The laboratory work for the second semester consists of work in qualitative analysis. Two three-hour periods per week is the time allowed. We have modified the order of attack quite radically, seeking to present qnalitative analysis in a way most helpful to our engineering students. I n another year we expect to have most of the rough spots smoothed out and then we will he ready to outline in more detail the work as we give it. From the classroom standpoint we have before us a t the opening of the second semester the task of surveying the metals and their compounds, of discussing the theoretical topics related to the qualitative course, such as solubility product, complex ion formation, etc., and of drill in equation writing and prediction of reactions. As we all know, correlation of the study of the metals with work in qualitative analysis is very difficult. We have tried both of the usual m e t h o d s one where the metals are discussed in the order of their qualitative grouping and the other where the periodic table is followed-and have come to the conclusion that the periodic grouping is the better one to follow. In the laboratory we begin by studying the anion analysis first. This follows nicely the work of the last week or two of the first semester and also gives us time to get the survey of the metallic elements under way in the classroom. There we discuss the occurrence, metallurgy, commercial preparation, properties, and uses of the metals. Then we examine their oxides, hydroxides, and any important salts. When the laboratory work reaches the point where the given metal is t o be studied we approach it from the standpoint of the behavior of the metal ion-its reduction and its oxidation, solubility relations of its various salts, and use of its chemical characteristics in separating it and devising tests for it. This gives us an opportunity to review and compare the behavior of the free element with its behavior in the ionized form. All this time we have been making use of the general principles and theory outlined during the first semester and i t is not unusual to find the men able to state with fair accuracy the important facts regarding a
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metal or some of its compounds after having located it in the periodic table and the electromotive series even though no text study of the metal has been made. Looking forward to the work of the sophomore year in quantitative analysis, we devote a week of class work to the study of oxidation-reduction in general. At the very beginning of the year's work we define oxidationreduction in terms of loss and gain of electrons, and toward the close of the first semester, in discussing the non-metals, we have called particular attention to their oxidizing-reducingbehavior. The discussion of the topic as a wholewhich comes about the tenth week of the second semester-then becomes, in part, a review of this very important subject and we feel it serves t o correlate many points in connection with chemical reactions in general. By using the reactions of potassium permanganate and potassium dichromate as class examples we make i t somewhat easier for the men when they meet these reactions the next year in their quantitative analysis. In closing each semester's work we have found it very profitable to devote one or two class periods to a survey of the subject. We ask the student to step back, so t o speak, from his text and watch us as we try to bring out in bold relief the line of thought running through the entire course. In our opinion, these lectures are probably the most valuable ones from the standpoint of the student. In this paper we have outlined a first-year course in chemistry planned for young engineering students who have had a year's work in high school. It has been shown that by eliminating much descriptive and historical matter and by introducing fundamental principles as early as possible in the course one can accomplish the work which is generally planned for both the general chemistry and the qualitative analysis courses.
