Matter and Measurement Review

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Matter and Measurement Review

• Chemistry

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Chemistry

• Is the study of matter
• Composition what matter is made of
• Structure how matter is assembled
• Change how matter can be changed

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Good Accuracy

• The known value
• Value closely agrees with accepted values

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Poor Precision

• Human error
• Limitations of the measuring instrument

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Precise

• The student massed the pennies
• She got values of 3.012, 3.016, and 3.015
• The accepted value is 3.200.
• Is her work accurate or precise?

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Physical change

• Chemical formula stays the same
• H2O changes from ice to water to steam
• Paper can be crumpled or cut
• Plastic can melt
• Car can be dented
• Shirt can be ironed

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Chemical Change

• Reaction to acid
• Reactivity to oxygen
• Difference in electrical potential
• Chemical formula changes
• Aluminum pot bottom shines with cleaner
• Candlestick tarnishes
• Potato clock runs on difference in potential
  between between copper and zinc
• Milk curdles in lemon juice

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Matter

• TWO PROPERTIES
• Mass
• Volume
• Not Matter
• Light
• Vacuum

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Density

• Concerns two properties
• Mass
• Volume
• Density is mass divided by volume
• D m/v

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States of matter

• SOLID
• Definite shape
• Volume definite

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States of Matter

• LIQUID
• Volume definite
• Shape not definite

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States of Matter

• GAS
• Volume not definite
• Changes shape to fit container

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Mixtures

• Homogeneous
• Solutions
• The same all through
• Salt water, lemonade no pulp, tea
• Heterogeneous
• With pieces
• Lemonade with pulp, fruit salad, potato salad

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Significant Figures

• 12 2
• 1098 4
• 2001 5
• 2.001 x 103 4
• 0.0000101 3
• 1.01 x 10-5 3
• 1,000. 4
• 22.0403 6

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Round to 4 significant figures

• Rounded
• 123.431 123.4
• 1.23431 1.234
• 12,434.1 12,340.0
• 550,092 550,100
• 90,221 90,220

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Round to 3 Significant Figures

• 0.000032421 .0000324
• 7,212,992 7,210,000
• 2.098988 x 10-7 2.10 x 10-7
• 550,092 550,000 NO is 2
• 
  5.50 x 105
• 199.99 200. or 2.00 x 102

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Round to indicated Sig Figs

• 102.4005 to five 102.40
• 15.995 to three 16.0
• 1.6385 to four 1.639
• 7.355 to three 7.40

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Round to indicated Sig Figs

• 0.50045 to four
  .5005
• 126.5 to three 127
• 15.395 to four 15.40
• 23.0975 to five 23.098

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Multiplying with Sig Figs

• When numbers are multiplied, the answer should
  contain the same number of sig figs as the
  multiplier with the LEAST number of sig figs.

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Dividing with Sig Figs

• When numbers are divided, the answer should
  contain the same number of sig figs as the
  multiplier with the LEAST number of sig figs.

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Adding,subtracting with Sig Figs

• When numbers are added or subtracted, the
  limiting term is the one with the SMALLEST NUMBER
  OF DECIMAL places.