The substance can be drawn into a wire density mass

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Unformatted text preview: ubstance can be hammered into thin sheets Ease with which the substance can be drawn into a wire Density = mass ÷ volume; density of water is 1kg/L; Acetic acid is sour 12 Copyright © 2007 by Concise Books Publishing LLC. Visit us at www.concisechem.com to download other free chapters from "The Concise Guide to Chemistry." CHAPTER 1: INTRODUCTION Physical Property TO CHEMISTRY Example/Definition a Often depends on its state of subdivision. b We say one substance is less hard than a second substance if is scratched by the second substance c Density usually increases when groin form gas to solid to liquid (more tightly packed), but there are a few exceptions. For example, ice has a greater density than liquid water. d Taste and odor are closely related with chemical nature of substances, and are often considered chemical properties even though we can get a chemical’s characteristic taste or odor without chemically changing it. • Chemical properties (Table 1.3) can only be observed when a substance is changed into another substance. Chemical changes are changes in matter that change the composition of a substance. For example, burning of a match is a chemical change. In the course of a chemical reaction, the reacting substances are converted into new substances. Physical Change: A + B → A + B (components retain their chemical properties) Chemical Change: A + B → C (new substance is formed) Table 1.4: Examples of Chemical Properties Substance Hydrogen Iron TNT Argon Example Burns explosively with oxygen to form water React with oxygen to form iron oxide (rust) Very explosive Inert gas (does not react) Sample Problem 1.4: We can use liquid nitrogen to freeze a flower. Is that physical or chemical change? Physical change; the chemical nature of the flower has not changed. Watch the video at http://www.youtube.com/watch?v=QaprCLxG5Tg. 1.3.3 • • Intensive & Extensive Properties of Matter Intensive properties are independent of the amount of the substance that is present. Some examples are density and boiling point. For example, the density of liquid water is always 1 kg/L regardless of how much water you have (d=m/V, so when mass , volume also proportionally, keeping density constant). Extensive properties depend upon the amount of the substance present. Mass, volume and energy are extensive properties. 1.3.4 Classification of Matter Follow Figure 1.2 through the discussion below. 13 Copyright © 2007 by Concise Books Publishing LLC. Visit us at www.concisechem.com to download other free chapters from "The Concise Guide to Chemistry." CHAPTER 1: INTRODUCTION TO CHEMISTRY Figure 1.3: Classification of Matter MATTER PURE SUBSTANCES Constant composition COMPOUNDS Two or more elements Chemical separation Physical separation ELEMENTS Only one kind of atoms MIXTURES Variable composition HOMOGENEOUS MIXTURES Same properties throughout HETEROGENEOUS MIXTURES Two or more phases Water (H2O) Air Chocolate chip cookie Salt (NaCl) • Gold (Au...
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This document was uploaded on 09/19/2013.

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