Chem0150f10ch3a(2)

Chem0150f10ch3a(2)

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  General Chemistry 0150Instructor: Professor Voytek Fall 2010 Chapter 3: Measurements and Problem Solving
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  WHAT IS CHEMISTRY?Chemistry is the study of matter and its properties , both at the macroscopic as well as at the atomic , subatomic and molecular levels. Chemists seek to understand the composition of matter, the changes that matter undergoes as well as the energy associated with these changes. Matter is anything that has mass and volume . It is the stuff of life. Everything around us (including us) is made up of matter.
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  SOME DEFINITIONS ChemicalProperties those which the substance shows as it interacts with, or transforms into, other substances Change(s) in composition but mass is conserved Matter anything that has mass and volume -the “stuff” of the universe. Composition What the matter is made of and how much each substance is present. Properties The characteristics that give each substance a unique identity . Physical (Intensive) Properties those which the substance shows by itself without interacting with another substance No change(s) in composition (such as State of Matter)
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  Classifying Matter accordingto composition
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  Practice Questions Classifyeach of the following substances as element, compound, homogeneous or heterogeneous mixtures: 1)methane CH 4 2)aluminum can 3)rocky road ice cream 4)tap water 5)distilled water
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  I-Clicker Question Bakingsoda (NaHCO 3 ) would be classified as: A)element B)compound C)heterogeneous mixture D)homogeneous mixture
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  Some Characteristic Propertiesof Copper DESCRIBING MATTER according to its PROPERTIES Physical Properties reddish brown, metallic luster easily shaped into sheets (malleable) and wires (ductile) good conductor of heat and electricity density = 8.95 g/cm 3 melting point = 1083 ° C boiling point = 2570 ° C Chemical Properties slowly forms a basic blue-green sulfate in moist air reacts with nitric acid and sulfuric acid slowly forms a deep-blue solution in aqueous ammonia
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  Telling matter apart(according to properties) Physical properties - properties that a substance displays without changing its composition Odor, color, taste, appearance, melting, boilig, freezing, weight, density Chemical properties - properties displayed only through changing its composition to yield a new substance combustion, oxidation, reduction, acid/base reactions
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  PHYSICAL AND CHEMICALCHANGES
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  PHYSICAL AND CHEMICALCHANGES
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  PHYSICAL AND CHEMICALCHANGES
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  I-Clicker Question Frostforms as the temperature drops on a humid winter night. A)physical change ? B)chemical change ?
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  I-Clicker Question Asunflower grows from a seed that is watered and fertilized. A)physical change ? B)chemical change ?
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  Mixtures can beconverted to pure substances by a physical processes such as through a filtration, distillation, chromatography, centrifuging, evaporation or sublimation to name a few.
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  Mixtures can beconverted to pure substances by a physical processes such as through a filtration, distillation, chromatography, centrifuging, evaporation, extraction, reverse osmosis or sublimation.
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  A magnet canbe used to separate iron metal from crystals of potassium dichromate:
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  Law of Conservationof Mass During physical and chemical changes, the total amount of matter remains the constant. In other words: Matter can neither be created nor destroyed This is known as the Law of Conservation of Matter (mass)
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  Law of Conservationof Mass Butane + Oxygen -> Carbon Dioxide + Water 58g + 208g -> 176g + 90g Reactants -> Products 266g = 266g Determine whether or not a matter is created, destroyed or conserved given the following: a chemist forms 16.6g of NaCl from 3.9g of Na and 12.7g of Cl.
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  I-Clicker Question 12gof natural gas combines with 48g of oxygen to form 33g of carbon dioxide and 20g of water. Is matter a)conserved b)created c)destroyed
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  DESCRIBING MATTER accordingto its STATE “The Four States of Matter” Solids: A substance with a fixed shape that will not conform to its container. Liquids: A substance that conforms to the container but will retain its own volume. Gas: A substance that both conforms to the container and fills the entire volume of the container.
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  DESCRIBING MATTER accordingto its STATE “The Four States of Matter” Plasma: A substance composed of ionized gas. It is the most common of all phases in the universe (space is comprised of sparse plasma); 99% of the known universe is in the plasma state. Common Plasma’s: Sun Stars Neon Signs Plasma TV’s (made of tiny cells that contain noble gases) *changes in state are physical properties of matter