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General Chemistry Principles, Patterns, and Applications, 2011

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Matter is anything that occupies space <strong>and</strong> has mass. The three states of matter are solid, liquid,<br />

<strong>and</strong> gas. A physical change involves the conversion of a substance from one state of matter to another,<br />

without changing its chemical composition. Most matter consists of mixtures of pure substances, which<br />

can behomogeneous (uniform in composition) or heterogeneous (different regions possess different<br />

compositions <strong>and</strong> properties). Pure substances can be either chemical compounds or<br />

elements. Compounds can be broken down into elements by chemical reactions, but elements cannot<br />

be separated into simpler substances by chemical means. The properties of substances can be classified as<br />

either physical or chemical. Scientists can observe physical properties without changing the<br />

composition of the substance, whereas chemical propertiesdescribe the tendency of a substance to<br />

undergo chemical changes (chemical reactions) that change its chemical composition. Physical<br />

properties can be intensive or extensive. Intensive properties are the same for all samples; do not<br />

depend on sample size; <strong>and</strong> include, for example, color, physical state, <strong>and</strong> melting <strong>and</strong> boiling<br />

points. Extensive properties depend on the amount of material <strong>and</strong> include mass <strong>and</strong> volume. The<br />

ratio of two extensive properties, mass <strong>and</strong> volume, is an important intensive property called density.<br />

K E Y T A K E A W A Y<br />

<br />

Matter can be classified according to physical <strong>and</strong> chemical properties.<br />

C O N C E PTUAL P R OBLEMS<br />

Please be sure you are familiar with the topics discussed in Essential Skills 1 (Section 1.9 "Essential Skills 1")<br />

before proceeding to the Conceptual Problems.<br />

1. What is the difference between mass <strong>and</strong> weight? Is the mass of an object on Earth the same as the mass of<br />

the same object on Jupiter? Why or why not?<br />

2. Is it accurate to say that a substance with a mass of 1 kg weighs 2.2 lb? Why or why not?<br />

3. What factor must be considered when reporting the weight of an object as opposed to its mass?<br />

4. Construct a table with the headings “Solid,” “Liquid,” <strong>and</strong> “Gas.” For any given substance, state what you<br />

expect for each of the following:<br />

a. the relative densities of the three phases<br />

b. the physical shapes of the three phases<br />

c. the volumes for the same mass of compound<br />

d. the sensitivity of the volume of each phase to changes in temperature<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

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