Unit 1

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Unit 1
2012-09-27 20:38:18

Chemistry and Measurement
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  1. Scientific Method
    • Observation
    • Questions
    • Hypothesis
    • Data
    • Conclustion
    • Results
  2. Hypothesis
    A tentative explanation based on observations
  3. Experiment
    An observation of natural phenomena carried out in a controlled manner so that the results can be duplicated
  4. Law
    States a measurable relationship
  5. Theory
    Tested explanation of basic natural phenomena
  6. Mass
    the quantity of matter in a material
  7. Matter
    occupies space
  8. Law of Conservation of Mass
    Matter can neither be created nor destroyed during a normal chemical reaction.
  9. What is the difference between mass and weight?
    Weight depends on gravity
  10. Solids
    Have a fixed shape and fixed volume
  11. Liquids
    Have a fixed volue but not a fixed shape
  12. Gases
    Do not have a fixed volume or shape
  13. Physical change
    A change in which the chemical composition of the sample does not change
  14. Chemical change
    A change in which the chemical composition of the sample changes. (new matter)
  15. Physical properties
    characteristics of a material that can be observed without changing the substance (its chemical identity)

    • appearance
    • density
  16. Chemical Properties
    characteristic of a material which is evident when the material undergoes a chemical change.

    • reactivity
    • toxicity
  17. Elements
    a pure substance that cannot be broken down any further by chemical means.

    oxygen, mercury, sulfur
  18. Compounds
    A combination of more than one element that can be broken down further by chemical reations.
  19. Heterogeneous mixtures
    a mixture in which the properties vary within a sample
  20. Homogeneous mixture
    a mixture in which the properties are constant throughout the sample.
  21. Precision
    How close the measurements are to one another
  22. Accuracy
    Closeness of a measurement ot its true value
  23. Uncertainty
    measurements cannot be exact
  24. Significant figues
    digits in a mesurement that include all certain digits plus a finial digit with some uncertainty.
  25. Rules to significant digits
    • non-zero significant
    • confined zeros significant
    • leading zeros not significant
    • trailing zeros significant with decimal
  26. Rounding
    • if next digit is >5 round up
    • if next digit is <5 round down
    • if next digit is =5 round to nearest even number
  27. Adding and Subtracting Sig Figs
    • Last common place that each number has
    • Round answer to place of least sig fig
  28. Multiplying and Dividing with Sig Figs
    Look at the number of sig fig in all values; report the fewest number of sig fig in answer
  29. Scientific Notation
    exponential notation where there is exactly one non-zero digit the the left of the decimal

    positive  <-  decimal  ->  negative
  30. Base units of metric system
    • length -> meter -> m
    • mass -> gram -> g
    • volume -> liter -> L
    • time -> second -> s
  31. Measurement staircase and rules
    • tera, giga, mega, kilo    base
    • deci, centi, milli, micro, nano, pico

    up stair divide by 10, down stair multiply by 10
  32. Celsius/Fahrenheit Conversion
    Tf = (9/5) Tc + 32.000 F
  33. Celsius/Kelvin Conversion
    Tk = Tc + 273.15
  34. Volume
    Length * Width * Height
  35. Density
    • Mass / Volume
    • g / mL
  36. Common conversions with liters
    • 1 L = 1 m3
    • 1 mL = 1 cm3