College Chemistry - Weebly

1 Page i College Chemistry Based on Schaum'sOutline of College Chemistry By Jerome L. Rosenberg and Lawrence M. Epstein Abridgement Editor:Philip H. Rieger Page ii Disclaimer:Information has been obtained by The McGraw-Hill Companies from sources believed to be reliable. However, because of the possibility of human or mechanical error by our sources, The McGraw-Hill Companies or others, The McGraw-Hill Companies does not guarantee the accuracy, adequacy, or completeness of any information and is not responsible for any errors or omissions or the results obtained from use of such information.

2 JEROME L. ROSENBERG did his graduate work at Columbia University in physical Chemistry , receiving his in 1944 and his in 1948. He is Professor Emeritus of Biological Sciences at the University of Pittsburgh. LAWRENCE M. EPSTEIN started his career as a chemical engineer, then earned his in 1952 and in 1955 from Polytechnic University in the field of physical Chemistry . He was Associate Professor and supervisor of the General Chemistry program at the University of Pittsburgh until he retired in 1986. PHILIP H. RIEGER is a graduate of Reed College and earned a from Columbia University.

3 He is Professor of Chemistry at Brown University, where he has taught since 1961. Copyright 2000 by The McGraw-Hill Companies, Inc. All rights reserved. Printed in the United States of America. Except as permitted under the Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a data base or retrieval system, without the prior written permission of the publishers. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 DOC DOC 9 0 9 8 7 6 5 4 3 2 1 0 9 ISBN 0-07-052714-8 Sponsoring Editor: Barbara GilsonProduction Supervisor: Tina CameronEditing Supervisor: Maureen B.

4 Walker Page iii Contents Chapter 1 Quantities and Units 1 Chapter 2 Moles and Empirical Formulas 10 Chapter 3 Calculations Based on Chemical Equations 20 Chapter 4 Concentration and Solution Stoichiometry 27 Chapter 5 The Ideal Gas Law and Kinetic Theory 32 Chapter 6 Thermochemistry 42 Chapter 7 Atomic Structure 50 Chapter 8 Chemical Bonding and Molecular Structure 59 Chapter 9 Solids and Liquids 75 Chapter 10 Oxidation-Reduction 83 Chapter 11 Properties of Solutions 92 Chapter 12 Thermodynamics and Chemical Equilibrium 99 Chapter 13 Acids and Bases 113 Chapter 14 Precipitates and Complex Ions 126 Chapter 15 Electrochemistry 133 Chapter 16 Rates of Reactions 143 AppendixTable of Atomic Masses 153 PREVIOUS CONTENTS NEXT Page 1 Chapter 1 Quantities and UnitsIN THIS CHAPTER.

5 Significant Figures Propagation of Errors The International System of Units Dimensional Analysis Estimation of Numerical AnswersIntroductionMost of the measurements and calculations in Chemistry are concerned with quantities such as pressure, volume, mass, and energy. Every quantity includes both a number and a unit. The unit simultaneously identifies the kind of dimension and the magnitude of the reference quantity used as a basis for comparison. The number indicates how many of the reference units are contained in the quantity being measured. If we say that the mass of a sample is 20 grams, we mean that the mass is 20 times the mass of 1 gram, the unit of mass chosen for comparison.

6 Although 20 grams has the dimension of mass, 20 is a pure dimensionless number , being the ratio of two masses, that of the sample and that of the reference, 1 gram. Page 2 Significant FiguresThe numerical value of every observed measurement is an approximation, since no physical measurement of temperature, mass, volume, etc. is ever exact. The accuracy of a measurement is always limited by the reliability of the measuring that the recorded length of an object is cm. By convention, this means that the length was measured to the nearest cm and that its exact value lies between and cm.

7 If this measurement were exact to the nearest cm, it would have been recorded as cm. We say that the first measurement is accurate to 3 significant figures and the second to recorded volume of L represents two significant figures. If this same volume were written m3, it would still contain only two significant figures. Zeroes appearing as the first digits of a number are not significant, since they merely locate the decimal often use scientific notation to express very large or very small numbers, indicating the number of significant figures by the number multiplied by 10x.

8 Thus, for example,When two exponentials are multiplied (or divided), the exponents are added (or subtracted). For example,When an exponential is raised to a power, the exponents are multiplied; for example,Some numbers are exact. These include ( ..), numbers arising from counting ( , the number of experimental determinations of an observed measurement), and numbers which involve a definition (the mass of one atom of 12C is exactly 12 u and the conversion of cm to m involves exactly 10-2 m/cm).A number is rounded off to the desired number of significant figures by dropping one or more digits from the right.

9 When the first digit dropped is less than 5, the last digit retained should remain unchanged; when it is greater than 5, the last digit is rounded up. When the digit dropped is exactly 5, the number retained is rounded up or down to get an even number . When more than one digit is dropped, rounding off should be done in a block, not one digit at a time. Page 3 Propagation of ErrorsWhen we perform a calculation using numbers of limited accuracy, the result should be written with the appropriate number of significant we add or subtract numbers, the number of significant figures in the answer is limited by the number with the smallest number of significant figures to the right of the decimal, ,This rule is an approximation to a more exact statement that the error in a sum or difference is the square root of the sum of the squares of the errors in the numbers being added or subtracted.

10 Thus in the above example, the error in the result isWhen multiplying or dividing two numbers, the result should contain only as many significant figures as the least accurate factor without regard for the position of the decimal point, ,This rule is an approximation to a more exact statement that the fractional error of a product or quotient is the square root of the sum of the squares of the fractional errors in the numbers being multiplied or divided. Page 4 Thus in the above examples, the fractional and absolute errors in the results are:The approximate and more exact approaches sometimes lead to different results when numbers beginning with 1 or 2 are involved.