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WVU CHEM 115 - Lecture 1 Exam 1 Material

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Chem 115Dr. Melissa [email protected] Prerequisite for Chem 115 is one of the following:1. Passing grade (C or better) in Chem 110B at WVU.2. Score of 600 or better on SAT/Math or score of 26 or better on ACT/Math.3. Minimum composite score of 24 on the two parts of the QRA (math placement exam).4. Transfer credit for Chem 110, 111, 112, or 115 from another institution.See me as soon as possible if this is your prerequisite. Proof of transfer credit (from Admissions and Records) must be shown.Include information about your prerequisite on the white card. Such as:a. Chem 110, 111, or 112 grade, instructor, and semesterb. Date and score of chemistry placement exam.c. ACT/Math or SAT/Math score.d. Transfer informationAny student without the proper prerequisite will be dropped from the roster!!Homework for Chem 115:1. Read syllabus.2. Chem 115 students need to purchase either the all digital package OR the Chem 115 package with access to Connect (so not both!). Both packages should contain access codes for the Connect and ALEKS online homework systems and both should have the Chemistry by Silberberg, 6thed. textbook. The all digital package provides the textbook in electronic form only whereas the regular Chem 115 package provides the textbook in print form.3. Purchase Chem 115 laboratory manual, goggles, and apron from the bookstore. (White aprons from Book Exchange are not permitted.) Bring manual, apron, and goggles to first lab (Tuesday, August 26th).4. Go to website for online homework: www.aleks.com. Register and begin working on the assessment.Exam 1 MaterialCHEMISTRYthe study of matter and its changesMatter: anything that has mass and takes up spaceThree physical states of matter:Solid – Particles of matter very close and touching.Not free to move (can’t flow).Definite volume and shape.Not compressible.Liquid- Particles of matter close and may be touching.Particles can move past one another (flow).Definite volume but no definite shape.Not compressible. Gas- Particles of matter are far apart (lots of empty space) and are not touching. Particles can move past one another (flow).No definite volume or shape (gases take shape/volume of the container).CompressiblePhysical vs. Chemical Properties of Matter• Physical properties are observed without the chemical makeup being changed.• BP, MP, density, color, conductivity, specific heat, etc.• Some examples of physical properties include: – whipping egg whites (air is forced into the fluid) – magnetizing a compass needle (realigns groups of iron atoms, but no real change within the iron atoms themselves)– boiling water (water molecules are forced away from each other when the liquid changes to vapor) – dissolving sugar in water (sugar molecules are dispersed within the water, but the individual sugar molecules are unchanged)• Chemical properties describes a chemical change that a substance undergoes.• heat of combustion, reactivity, pH, flammability, etc.• Some examples of chemical properties include:– iron rusting (iron oxide forms) – gasoline burning (water vapor and carbon dioxide form) – eggs cooking (fluid protein molecules uncoil and crosslink to form a network) – bread rising (yeast converts carbohydrates into carbon dioxide gas) – milk souring (sour-tasting lactic acid is produced) Physical vs. Chemical Changes of Matter• Physical change rearranges molecules but doesn't affect their internal structures. May change the physical state or proportions.• Examples:– dissolving sugar in water (sugar molecules are dispersed within the water, but the individual sugar molecules are unchanged)– boiling water (water molecules are forced away from each other when the liquid changes to vapor)• Chemical change is any change that results in the formation of new chemical substances. At the molecular level, chemical change involves making or breaking of bonds between atoms.• Examples: – gasoline burning (water vapor and carbon dioxide form) – bread rising (yeast converts carbohydrates into carbon dioxide gas) – milk souring (sour-tasting lactic acid is produced) – iron rusting (iron oxide forms)8/13/2014 1.3. Properties of materials can be classified in different ways7Intensive And Extensive Properties• Intensive properties are independent of sample size. Examples: density and color• Extensive properties depend on the amount of material examined. Examples: mass and volume• Properties used to identify substances are always intensive.– Density, color, and texture are often helpful in identification, but temperature is not.8/13/2014 1.3. Properties of materials can be classified in different waysLearning CheckChemical PhysicalMagnesium metal is greyThe density of Magnesium metal is 1.738 g/cm3Magnesium metal melts at 922KMagnesium reacts violently with hydrochloric acidA. Chemical or Physical Property?Chemical PhysicalMagnesium burns when heated in a flameMagnesium metal tarnishes in airMagnesium metal melts at 922KGrape Kool-aid lightens when water is addedB. Chemical or Physical Change?Classification of MatterMatterPure Substances MixturesHomogeneousMixturesHeterogeneousMixturesCompounds ElementsComposed of two or more elements and has constant composition. Substances that can’t be decomposed into simpler materials. Simplest form of matter. Has the same propertiesthroughout.Has different propertiesthroughout and 2 or more phases.Can be a mixture of two or more pure substances. Has a variable composition. What Is An Element?• Elements are substances that cannot be decomposed into simpler substances• Elements are shown on the periodic table as symbols, such as “K” for potassium and “Na” for sodium• Only 90 occur naturally• Elements are made of identical atoms, either singly or in groupstungsten74W183.83vanadium23V50.942uranium92U238.03Applying School Spirit to Elemental ChemistryWhat Is A Compound?• Compounds are formed from two or more atoms of different elements combined in a fixed proportion [shown as a chemical formula, Ex. Sodium Sulfide (Na2S)]• In a compound, elements cannot be separated by physical means but can be broken down by some chemical changes – For example, water can be subjected to electricity and it decomposes to elemental hydrogen and elemental oxygen: 2H2O(l)→2H2(g)+ O2(g)Mixtures• A mixture consists of varying amounts of two or more elements or compounds• Homogeneous mixtures or solutions have the same


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