Metrics

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Chemistry 1

• Metrics measurement

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Metric Units

• Volume How much space something takes up,
  measured in Liters or milliliters (cm3).
• Mass(weight) measured in grams, milligrams or
  kilograms.
• Length measured in meters, millimeters, or
  centimeters.

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Metric Multiples

• The great advantage of using metric units is that
  they are in multiples of ten. This means that you
  can simply move decimal points to go from one
  unit to another!

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Metric Multiples

• Kilo-K
• Hecta-H
• Deka-Dk
• Base units meters, Liters, grams
• Deci-d
• Centi-c
• Milli-m

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Metric Multiples

• km Hm dkm m dm cm
  mm
• To change metric units, simple move the
  decimal place along the scale from one unit to
  another. 25 meters becomes 2500 centimeters.

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Metric Conversions

• 23.5 g to mg (23,500 mg)
• 435.7 ml to L (.4357 L)
• .223 km to m (223m)
• 22.57 cm to m (.2257 cm)
• 450.3 L to ml
• 45 mg to g

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Density the mass (grams) divided by the volume
(milliliters) D m/v

• Find D for
• A piece of cork with a volume of ml water that
  weighs .41 grams. (.205 g/ml)
• A rock that displaces 10 ml water has a weight of
  30 grams. (3 g/ml)
• A chunk of ice which has a volume of 25 ml weighs
  23 grams. (.91 g/ml)

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Uncertainty in Measurements because
measurements always have flaws and they always
involve estimation

• Significant Digits the number of certain and
  estimated digits in a number.
• Zeroes to left of decimal point and to left of an
  integer do not count as significant.
• All other zeroes do count as significant.
• 31.76 (4 s.d.)is more accurate than 31.7 (3 s.d.)
• .009210 (4 s.d.) 9.210 x 10-3
• .0090210 (5 s.d.) 9.0210 x 10-3

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Significant digit Calculations

• When doing math, your answer can only have as
  many sigdigs as the lesser number of sigdigs
• 1.12 2.243 3.363 3.36
• (3 sigdigs) (4 sigdigs) (4 sigdigs) (3 sigdigs)
• This answer can only have 3 significant digits
  since 1.12 only has 3 digdigs.

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Base Ten Exponents

• The exponents you will use in this class
  represent numbers which have the number of
  decimal places in the exponent 100 1 101 10
  102 100 and so on.
• Positive exponents push the decimal place to the
  right 2.35 x 103 is 2,350
• Negative exponents push the decimal place to the
  left 2.35 x 10-3 is .00235

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Exponent Calculations

• When multiplying exponential numbers, multiply
  the first two, then add the exponents 1.2 x 103
  x 1.2 x 103 1.44 x 106
• When dividing exponential numbers, divide the
  first two, then subtract the exponents
• 1.2 x 103 / 1.2 x 103 1.0 x 100 1

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Exponent Calculations

• To add exponents, move the decimal place to get
  the same exponents, then add the numbers, keeping
  the exponent. 1 x 102 1 x 103 1 x 102 10 x
  102 11 x 102
• To subtract exponents, move the decimal place to
  get the same exponents, then subtract the
  numbers, keeping the exponent. 1 x 103 - 1 x 102
  
• 10 x 102 - 1 x 102 9 x 102

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Try These!

• 5.4 x 107 2.7 x 106
• 2.3 x 1016 1.8 x 1015
• 8.4 x 1024 / 4.2 x 1022
• 3.2 x 103 x 2 x 1012

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Percent Error and Yield

• Percent Yield Actual x 100
• Expected
• Percent Error Actual Expected x 100
  
• Expected

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Dimensional analysis

• Used to convert units. Multiply the given by the
  unit you want to find on the top, and the unit
  you want to cancel on the bottom.
• 10.5 mm ? Meters
• 10.5 mm x 1 meter .0105 meters
• 1,000 mm

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Measurement

• Hot or Not?

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Definitely Hot!
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The End