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Chapter 1: Chemistry Chapter 2: MATTER, CHANGE, & ENERGY. What is Chemistry?. Chemistry: the study of the composition of substances & the changes they undergo. PURE vs. APPLIED Chemistry Pure Chemistry: knowledge is accumulated for its own sake. Water boils
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What is Chemistry? • Chemistry:the study of the composition of substances & the changes they undergo. • PURE vs. APPLIED Chemistry • Pure Chemistry: knowledge is accumulated for its own sake. Water boils • Applied Chemistry: knowledge is used in ways that either benefit or harm people or environment.Boiling water can be used to sterilize
PURE CHEMISTRYLEADS TOAPPLIED CHEMISTRY5 TRADITIONAL AREAS OF STUDY in Chemistry:1.Organic-study of substances that contain carbon2.Inorganic-study of substances without carbon 3.Analytical-study of the composition of substances4.Physical-study of theories & experiments that describe the behaviors of chemicals 5. Biochemistry-study of the chemistry of living organisms
What is the Scientific Method? • The Scientific Methodis an approach to the solution of scientific problems. • The number of steps involved varies from • reference to reference but in general there are 5 basic steps: • Observations • Hypothesis • Experiments • Theory • Scientific Law
BREAKDOWN OF THE 5 STEPS:Observation:Why does something happen?Hypothesis:A proposed reason for what is observedExperiment:To prove or disprove the hypothesisTheory:Thoroughly tested explanation of why experiments give certain results1.Time Tested Concept2.Useful & dependable predictions about the natural world3. Can never be proved; new experiments can disprove it4.Can be wrong & changedEX: Big Bang TheoryScientific Law:Summarizing statement of observed experimental facts 1.Accepted as TRUE2.Can be proven and proven and proven3.Often expressed by simple mathematical relationshipsEX: Sir Isaac Newton’s Law of Motion
What are the states of matter? Solid:matter that has definite shape & volumepacked closely together o can’t be compressed Liquid:matter that has no definite shape but definite volume (flows) o takes the shape of the container Gas:matter that has no definite shape or volume o expands without limits-free to move Vapor—the gaseous state of a substance that is usually a liquid or solid at room temperature. Plasma---4th state that exists at very high temperatures.
Physical & Chemical PropertiesPhysical Property: Can be observed or measured w/o alternating the identity of the materialEX: color, solubility, hardness, density, b.p. & m.p.Physical Change:Alters a substance w/o changing its compositionEX: cutting, freezing, melting, dissolving, & boiling USUALLY REVERSIBLEChemical Property: The ability of a substance to undergo a change that alters its identityEX: rot, rust decompose, ferment, corrode, & decayChemical Change or Reaction:Any change when one or more substances are converted into NEW substances NOT EASILY REVERSIBLEReactants: Starting substances that undergo changeProducts: New substances that are produced
Indications of Chemical Reactions:1.Evolution of heat and light2.Production of a gas3.Formation of a precipitateLaw of Conservation of MassMass in neither created nor destroyedMass of Products = Mass of Reactants