Chemical Calculations

Bernard Jafee, Iisc Library, Iisc

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• Publié par: iproo
• Nombre de lectures: 36
• Langue: English
• Poids de l'ouvrage: 4 Mo

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CHEMICAL CALCULATIONSF.Courtesy of Charles Roth toAntoine Laurent Lavoisier "It was left to Lavoisier transform a(1743-1794). tenet of Conservation of into a fruitful scientificphilosophical (Law Matter) prin- and to it to the of chemicalciple, apply interpretation phenomena." BERTHELOT, La Revolution Chimique.SERIESNEW-WORLD SCIENCE W'. RitchieEdited by John CHEMICAL CALCULATIONS PRESENTATION OF THE SOLUTION OFA SYSTEMATIC TYPE WITH IOOO CHEMICAL PROBLEMSPROBLEMS, ARRANGED PROGRESSIVELY ACCORDING TO LESSON ASSIGNMENTS BERNARD M.A.JAFFE,By Instructor in SchoolChemistry, Jamaica High New York City Tankers-on-Hudson New Tork y WORLD BOOK COMPANY 2126 Prairie Avenue, Chicago 1927WORLD BOOK COMPANY THE HOUSE OF APPLIED KNOWLEDGE Established W.1905 by Caspar Hodgson T YONKERS-ON NEW YORK --HUDSON, 2126 PRAIRIE CHICAGOAVENUE, textbooks intended to be used inChemistry high school and classesbeginning college havebeenfound many teachers to containby rather too few in the mathematicsproblems of the subject. Yet in examina-chemistry tions undergiven state as insupervision, New and in entrance examina-York, college tions three of tenperhaps questions out mathematical calculations. Itrequire was to thehands ofprimarily strengthen teachers a in some of theby overcoming deficiency basal texts in that this book ofchemistry Chemical Calculations was prepared NWSS : JCC-2 WorldCopyright 1926 by Book Company in Great BritainCopyright All rights reserved WONTED IN tr.S.A.PREFACE IN an of the results secured in the of investigation teaching in 1922school conducted Professor Samuelhigh chemistry, by R. Powers 'of Teachers Columbia one of College, University, the weaknesses found was the of theoutstanding inability to use chemical arithmetic. Professor Powers writespupils the students in the schoolsconcerning first-year chemistry that "fewer than 60 centexamined are able toper compute the molecular of when the of a liter of theweight gases weight less than 50 cent areis able to calculate a for-gas given, per mula from the molecular andweight percentage composition, cent are toand 40 able make the calculations involv-only per a of Law. About one ofout three ising knowledge IJoyle's able to calculate from the the ratiopercentage .composition between the amounts of in the two oxides of sulfur.oxygen A little more than 10 cent are able to calculate from theper the ratio between the amounts ofpercentage composition in thetwo oxides of theseoxygen nitrogen. Certainly percent- would be smaller if all the schools had usedages cooperating this test. The test was used by schools."distinctly superior The reasons for this weakness are not difficult to find. A of the various textbooks onstudy elementary chemistry reveals in most of them a reference to the sub-only passing when a moreject; or, treatment iscomprehensive given, both teacher and are a dearth ofpupil byhandicapped prop- to hand inerly graded problems hand with thego regular lesson few teachersdaily assignment. Very their stu-give dents a of chemical calculations.systematic presentation The ^airrr of this book is to fill the which teachers ofgap in 'schools have felt exists in most ofchemistry secondary the textbooks used. To vitalize and make it a morechemistryPrefaceVI teachers to introduceworkable science has stimulated the chemical and the trend of the last fewofsolving problems, seems to be toward more mathematical chemistry. Byyears method becomes an exact science to the stu-this chemistry since he soon realizes that data are funda-dent, quantitative mental and that even the minutest of matter in their particles reactions mathematical laws.obey The in this book are ac-problems progressively arranged to anumber of which the student soon learns tocording types are also to of diffi- recognize. They graded according degree and order of lesson A minimum ofculty assignment. algebra is Since the is to teach not mathematics required. purpose but arithmetical calculations have been reduced tochemistry, a minimum. Whole numbers are used for the atomic weights of the elements. The constant ofchanging as issued the International and theCommittee, recentby researches on this The studentisotopes, justify practice. is the labor of a maze of coldspared wading through figures. The time saved in out that involve a mul-working problems titude of can fie used in otherfigures doing problems. In it is often to dealanalytical work, however, necessary with a number of with a fine oflarge figures degree accuracy. solutions must be obtained to save the time of theRapid chemist. For such work the Chemists' Slide Rule (sold by Keuffel & Esser is recommended. Besides' theCompany) CD and CI this slide rule has two sets ofscales, scales with the and formulas of used elements andsymbols commonly marked at thecompounds theirpoints representing respective atomic and molecular thusweights, making theunnecessary ofuse atomic and molecular tables.weight This book is todesigned primarily of theaccompany any more recent textbooks on Part II hasgeneral chemistry.' Preface vii for usebeen added and in thoseby first-year college students, schools where courses in andhigh qualitative quantitative are offered. analysis wishes to hisThe author forexpress gratitude," helpful advice and to Mr. S. of the suggestions, Jaffe Boys' High New York Mr. M. Mendel of the ThomasSchool, Brooklyn, ; New and Mr. M.Jefferson High School, Brooklyn, York; his at the School.Dunay, colleague Jamaica High BERNARD JAFFESUGGESTIONS FOR THE USE OF THIS BOOK cultivate a method of1. Aim. This book aims to attack in With aon mathematical chemistry. knowledgeproblems of the ten of in Part the studenttypes presented I, will mid little trouble in all the common solving practically chemical problems. 2. It is the of the author that all of Part I Scope. -opinion should be mastered school student. Part IIby every high is, on the intended for more mature whole, students, especially students.first-year college 3. Time to The introduction of lawsbegin. quantitative should be reached as as This book shouldearly possible. be used in with thethen textbook. Theconjunction regular is to the of thegeneral begin studyprocedure first-type prob- lem about the fourth, week after the of the coursebeginning and after chemical law ofelements, compounds, changes, definite oflawproportions, oxygen, hydrogen, multiple pro- and the Atomic have been studied.portions, Hypothesis and the of balanced should beValency writing equations introduced early. 4. Rate No rules can be set down. Itof progress. rigid the of in the school cur-depends upon position chemistry the andmentalriculum, attainments of the the sizeage pupils, of and other factors. The work should notclasses, varying be in too doses. In schools on the Daltongiven large operated or the Winnetka Plan this book is as it especially valuable, meets the needs of the individual student. 5. Lesson The book follows theassignments. order of which have become moretopics or less standard in the teach- of The student should master eaching chemistry. type prob- lem before on to the next one. Problems should bepassingfor the Use of This Book ixSuggestions from Part III to vitalize the lesson. The assigned daily prob- lems under each in Part III cover varioustopic type problems. have been selected to teach chemical facts. ProblemsThey from the Examinations and the. EntranceRegents College Board Examinations should be from time to timeassigned to the student confidence in his to solvegive suchability problems. 6. Problem book. All shouldproblems be done ,theby student in a book. Problems shouldspecial problem be discussed in class the and correctionsfollowing day necessary made. This clear Thedevelops thinking. proper handling of these can serve asproblems a review. 7. Review work. The topical of Part IIIarrangement facilitates reviews. The important equations theclarify student's ofknowledge and commerciallaboratory prepa- rations and fix in his mind the chemical and usesproperties of the substances studied. Part III should ofprove great value in the final review. 8. Answer book. A the answers to allpamphlet containing the be obtained teachers from theproblemsmay by publishers.