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Chem 101 Chapter 1- Matter

Chem 101 Chapter 1- Matter - The Basic Tools of Chemistry...

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10 How Hot Is It? “It’s so hot outside you could fry an egg on the sidewalk!” This is an expression we heard as children. But what does it mean to say that something is hot? We would say it has a high temperature—but what is temperature and how is it measured? Temperature and heat are related but different concepts. Al- though we will discuss the difference in more detail in Chapter 6, for the moment it is easy to think of them this way: Temperature deter- mines the direction of heat transfer. That is, heat transfers from something at a higher temperature to something at a lower tempera- ture. If you touch your finger to a hot match, heat is transferred to your finger, and you decide the match is hot. Early scientists learned that gases, liquids, and solids expand when heated. In his investigations of heat, Galileo Galilei (1564–1642) invented the “thermoscope,” a simple device that depended on the expansion of a liquid in a tube with increasing temperature. Others developed instruments based on this principle, using liquids such as alcohol and mercury. Among them was Daniel Gabriel Fahrenheit (1686–1736). To create his scale, Fahrenheit initially assigned the freezing point of water as 7.5 °F and body temperature as 22.5 °F. He multiplied these values by 4, and then later adjusted them so that the freezing point of water was 32 °F and body temperature was 96 °F. After Fahrenheit’s death a further revision of the scale established the reference temperatures at their current values, 32 °F for the freezing point of water and 212 °F for the boiling point. On the current scale, normal body temperature is 98.6 °F. 1 Matter and Measurement NPL photograph © Crown copyright 1997. Reprinted with permission of the controller of HMSO. The Basic Tools of Chemistry Platinum resistance thermometer. This device measures temperatures over a range from about 259 C to 962 C. ° ° Anders Celsius (1701–1744). Swedish astronomer and geog- rapher. Archives of the Royal Swedish Academy of Sciences
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Chapter Outline 1.1 Classifying Matter 1.2 Elements and Atoms 1.3 Compounds and Molecules 1.4 Physical Properties 1.5 Physical and Chemical Changes 1.6 Units of Measurement 1.7 Making Measurements: Precision, Accuracy, and Experi- mental Error 1.8 Mathematics of Chemistry Chapter Goals See Chapter Goals Revisited (pages 46 and 47). Test your knowledge of these goals by taking the exam-prep quiz on the General ChemistryNow CD-ROM or website. Classify matter. Recognize elements, atoms, compounds, and molecules. Identify physical and chemical properties and changes. Apply the kinetic-molecular theory to the properties of matter. Use metric units and significant figures correctly. Understand and use the mathematics of chemistry. A significant advance in temperature measurement came from Anders Celsius (1701–1744). Celsius was a Swedish geographer and astronomer who constructed the Celsius thermometer, which used liquid mercury in a glass tube. The Celsius thermometer scale origi- nally used 0 as the boiling point of water, and 100 as the freezing
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