RRoobbeerrtt GGaarrddnneerr This page intentionally left blank Chemistry! BBEESSTT SSCCIIEENNCCEE PPRROOJJEECCTTSS Using Acids, Bases, Metals, Salts, and Inorganic Stuff Robert Gardner Copyright © 2004 by Robert Gardner All rights reserved. No part of this book may be reproduced by any means without the written permission of the publisher. Library of Congress Cataloging-in-Publication Data Gardner, Robert, 1929– Chemistry science fair projects using acids, bases, metals, salts, and inorganic stuff / Robert Gardner. v. cm. — (Chemistry! best science projects) Includes bibliographical references and index. Contents: Identifying substances — Conservation of matter — Some chemical reactions and their reaction speeds — Energy in chemical and physical changes — Acids, bases, ions, and an electric cell. ISBN 0-7660-2210-2 (hard cover) 1. Chemistry—Experiments—Juvenile literature. 2. Science projects— Juvenile literature. [1. Chemistry—Experiments. 2. Experiments. 3. Science projects.] I. Title. II. Series. QD38.G35 2004 540’.78—dc22 2003027476 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 To Our Readers:We have done our best to make sure all Internet Addresses in this book were active and appropriate when we went to press. However, the author and the publisher have no control over and assume no liability for the material available on those Internet sites or on other Web sites they may link to. Any comments or suggestions can be sent by e-mail to [email protected] or to the address on the back cover. Illustration Credits:Tom LaBaff Cover Photo:Copyright © 2002–2004 Art Today, Inc. (model); Matt Meadows/Photo Researchers, Inc. (beaker). Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 Identifying Substances . . . . . . . . . . . . . . . . 11 1.1 Separating the Components of a Mixture. . 14 1.2 Separating by Chromatography. . . . . . . . 18 1.3 Using Density to Identify Liquids. . . . . . 21 1.4 Using Density to Identify Solids . . . . . . . 26 1.5 The Density of Pennies, New and Old . . 29 1.6 Identification by Melting. . . . . . . . . . . . . 31 1.7 The Melting and Freezing Temperature of Water (Ice). . . . . . . . . . . . . . . . . . . . . 33 1.8 The Boiling Temperature of Water . . . . . 39 1.9 Using Solubility to Identify Substances . . 43 Conservation of Matter . . . . . . . . . . . . . . . 46 2.1 Does Weight Change When Water Freezes?. . . . . . . . . . . . . . . . . . . . 47 2.2 Lavoisier and a Chemical Law . . . . . . . . 48 2.3 Paper Clips, Washers, “Chemical Formulas,” and Laws of Nature . . . . . . . 54 Some Chemical Reactions and Their Reaction Speeds . . . . . . . . . . . . . . . . 59 3.1 Rusting of Iron. . . . . . . . . . . . . . . . . . . . 60 3.2 What Fraction of Air Is Oxygen? . . . . . . 61 3.3 Preparing and Testing Oxygen . . . . . . . . 64 3.4 The Rate at Which Hydrogen Peroxide Decomposes. . . . . . . . . . . . . . . 68 3.5 Factors Affecting the Rate of a Reaction . . 73 Energy in Chemical and Physical Changes . . . . . . . . . . . . . . . . . . . . 77 4.1 The Energy (Heat) Needed to Melt Ice. . 79 4.2 The Energy (Heat) Needed to Boil Water . . . . . . . . . . . . . . . . . . . . . . . 82 4.3 The Heat of Condensation. . . . . . . . . . . 88 4.4 Energy Changes During Physical and Chemical Changes . . . . . . . . . . . . . . . . . 93 4.5 A Chemical Reaction: Reactants, Products, and Energy Changes. . . . . . . . 96 Acids, Bases, Ions, and an Electric Cell . . 103 5.1 Ions and Electric Current . . . . . . . . . . . . 104 5.2 Identifying Acids and Bases . . . . . . . . . . 109 5.3 Indicator Papers and Sticks. . . . . . . . . . . 114 5.4 Neutralization . . . . . . . . . . . . . . . . . . . . 115 5.5 pH, a Measure of Hydrogen Ion Concentration. . . . . . . . . . . . . . . . . . 119 5.6 Building an Electric Cell . . . . . . . . . . . . 122 Appendix: Science Supply Companies . . . 125 Further Reading and Internet Addresses . . . . . . . . . . . . . . . . . . . 126 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Chemistry is the part of science that deals with what materials are made of and how they combine with one another. Chemists know how to keep your new bike from rusting, why pizzas are delivered in insulated bags, and what to use to remove stains from your clothing. They divide their work into two types: the study of materials that are organic and those that are not. Organic chemistry deals with compounds containing carbon, many of which are found in living things such as plants and animals. Inorganic chemistry studies all the other sub- stances, such as water, air, metals, salts, and many more. This book will focus on projects and experiments related to inor- ganic chemistry. Another book in this series covers organic chemistry. Most of the materials you will need to carry out the pro- jects and experiments described in this book can be found in your home. Several of the experiments may require items that you can buy from a supermarket, a hobby or toy shop, a hard- ware store, or one of the science supply companies listed in the appendix. Some of the experiments in Chapters 2, 3, and 4 require special equipment, like a Bunsen burner. As you begin to use this book, show it to one of the science teachers in your school. Perhaps the teacher will allow you and some of your friends to use the school’s equipment. At times, you will need a partner to help you. It would be best if you work with 5 Chemistry Science Fair Projects friends or adults who enjoy experimenting as much as you do. In that way you will both enjoy what you are doing. If any danger is involved in doing an experiment, it will be made known to you. In some cases, to avoid any danger to you, you will be asked to work with an adult. Please do so. We do not want you to take any chances that could lead to an injury. Like any good scientist, you will find it useful to record your ideas, notes, data, and anything you can conclude from your experiments in a notebook. By so doing, you can keep track of the information you gather and the conclusions you reach. It will allow you to refer to experiments you have done and help you in doing other projects in the future. SCIENCE FAIRS Some of the projects in this book are followed by a section called “Science Project Ideas.” These ideas may be appropri- ate for a science fair. However, judges at such fairs do not reward projects or experiments that are simply copied from a book. For example, a diagram or model of an atom or molecule would not impress most judges; however, a unique method for finding out how the rate of a chemical reaction is affected by temperature or pressure would attract their attention. Science fair judges tend to reward creative thought and imagination. It is difficult to be creative or imaginative unless you are really interested in your project. Consequently, be sure 6 Introduction to choose a subject that appeals to you. And before you jump into a project, consider, too, your own talents and the cost of materials you will need. If you decide to use a project found in this book for a sci- ence fair, you should find ways to modify or extend it. This should not be difficult because you will discover that as you do these projects, new ideas for experiments will come to mind— experiments that could make excellent science fair projects, particularly because the ideas are your own and are interesting to you. If you decide to enter a science fair and have never done so before, you should read some of the books listed in the further reading section. These books deal specifically with science fairs and will provide plenty of helpful hints and lots of useful infor- mation that will enable you to avoid the pitfalls that sometimes plague first-time entrants. You will learn how to prepare appealing reports that include charts and graphs, how to set up and display your work, how to present your project, and how to relate to judges and visitors. THE SCIENTIFIC METHOD Doing a science project, particularly one that involves origi- nal research, will require you to use what is commonly called the scientific method. In many textbooks you will find a sec- tion devoted to the subject. It will probably tell you that the 7 Chemistry Science Fair Projects scientific method consists of a series of steps. The book may even list the steps in a particular order. While such a cut-and-dried explanation may appeal to someone starting out in science, any seasoned scientist will tell you that there is no set pattern that leads him or her to new knowledge. Each investigation is unique and requires different techniques, procedures, and thought processes. Perhaps the best description of the scientific method was given by Nobel prize–winning physicist Percy Bridgman. He said that it was doing one’s best with one’s mind, no-holds-barred. The idea that there is a set scientific method that all scien- tists follow probably came about because of the way scientists report their findings. These reports are very similar in format and include the problem, the hypothesis (a possible solution), the experimental procedure, the results, and a conclusion. You will follow a similar format when you prepare the report on your project. The format will include references to authority (searching the literature), coming up with a question, and forming a hypothesis. You will then conduct experiments, report the data, and look for relationships or patterns in the experimental variables and controls that may lead to a conclu- sion based on the results of your experiments. SAFETY FIRST Most of the projects included in this book are perfectly safe. However, the following safety rules are well worth reading 8