u1 - Outline Unit 1 Introduction to Chemistry Internet web...

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Unit 1 Introduction to Chemistry Internet web site: www.unit5.org/chemistry Outline PowerPoint Presentation by Mr. John Bergmann
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Safety
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Basic Safety Rules Use common sense. No horseplay. No unauthorized experiments. Handle chemicals/glassware with respect. Others: #1 Rule:
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Safety Features of the Lab safety shower fire blanket fire extinguisher eye wash fume hood circuit breaker switch
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Material Safety Data Sheet (MSDS) gives information about a chemical -- lists “Dos” and “Don’ts;” emergency procedures --
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Chemical Exposure a one-time exposure causes damage acute exposure chronic exposure damage occurs after repeated exposure reaction to drugs or medication e.g., e.g., smoking, asbestos
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the lethal dosage for 50% of the animals on which the chemical is tested LD50 There are various ways an LD50 can be expressed. For example, acetone has the following LD50s: ORL-RAT LD50: 5,800 mg/kg IHL-RAT LD50: 50,100 mg/m3-h SKN-RBT LD50: 20 g/kg
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Example Which is more toxic? Chemical A is more toxic because less of it proves fatal to half of a given population. Chemical A: LD50 = 3.2 mg/kg Chemical B: LD50 = 48 mg/kg
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Science
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The Functions of Science pure science applied science the search for knowledge; facts using knowledge in a practical way e.g., aluminum strong lightweight good conductor
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Science attempts to establish cause-effect relationships.
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risk-benefit analysis weigh pros and cons before deciding Because there are many considerations for each case, “50/50 thinking” rarely applies.
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How does scientific knowledge advance? 1. curiosity 2. good observations 3. determination 4. persistence
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The Scientific Method
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** Key: Be a good observer. observation inference involves a judgment or assumption uses the five senses
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Types of Data Observations are also called data . qualitative data quantitative data clear liquid -- -- e.g., e.g., descriptions measurements 55 L or 83oC
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Parts of the Scientific Method Identify an unknown. Make a hypothesis : a testable prediction Repeatedly experiment to test hypothesis. procedure : order of events in experiment variable : any factor that could influence the result (i.e., a recipe)
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A Scientific Experiment conclusion: must be based on the data Experiments must be controlled : they must have two set-ups that differ by only one variable
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