Scientific Measurements

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Pflugerville Independent School
District Integrated Physics Chemistry
Measurement
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Quantitative and Qualitative Observations

• What do YOU think
• the difference is?

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1) What is a system of measurement ?

• 2) Metric system- AKA International system , and
  SI (Systeme International d'Unites)
• English system- AKA British system, customary
  system our system
• 3, 4, 5, 6) METRIC!!!!!!

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7 Base Metric Units

• Meters measure length
• Kilograms measure mass
• Seconds measures time
• Kelvin measures temperature
• Ampere measures current
• Lumens measures light intensity
• Moles measures the amount of a substance

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Metric Prefixes

• Kilo 1000
• Hecto 100
• Deka 10
• Deci 1/10
• Centi 1/100
• Milli 1/1000

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Other Derived Metric Units (from basic 7)

• Volume is length x width x height measured in
  centimeters cubed or millilters
• Temperature is measured in degrees celsius or
  centigrade (oC)
• Heat is measured in calories (cal) or joules (J)
• Weight is measured in newtons (N)

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How Big?

• A meter is about 39 inches
• A kilometer is 0.6 mile
• A centimeter is about the width of your little
  finger
• A gram is about the mass of a paper clip
• A kilogram is 2.2 pounds
• You drink 2 liters of pop
• See handout for other prefixes

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Tools for Measurement

• Thermometer
• Multimeter
• Photometer

• Meterstick
• Balance (triple beam and digital)
• Graduated Cylinder
• Stopwatch

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Graduated CylinderMeasurement

• Volume is measured using a graduated cylinder.
• When reading a graduated cylinder, read the
  bottom of the meniscus.

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Insert Slides on Dimensional Analysis

• From Bill Anderson, HHS

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K H D O D C M

• To change from one metric unit to another, we
  simply multiply by a conversion factor.
• For example
• 25.4 km _____________ cm?
• 25.4 km x 1000cm/1km 2,540,000 cm

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Scientific Notation

• Rules
• 1 digit before the decimal point
• Multiply the number by a power of 10
• Example Write 34,000 in scientific notation.
• Solution 3.4 x 104

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Write the following in scientific notation
4.1 x 106

• 4,100,000 _______________
• 345,600,000,000 _________
• 0.0456 ________________
• 0.00000012____________
• O.00305 ____________

3.456 x 1011
4.56 x 10-2
1.2 x 10-7
3.05 x 10-3
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Write the following in standard form
4670

• 4.67 x 103 __________________
• 3.112 x 105 _________________
• 3.112 x 10-4 ________________
• 4 x 10-6 ___________________
• 1 x 1011 __________________

311200
0.0003112
0.000004
100,000,000,000
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Density of Water

• One milliliter of water
• Has a mass of 1 gram
• Density Mass Volume
• Calculate the density of water

1g 1mL 1g/mL
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Measuring Water

• If you wanted to measure 25 mL of water, what
  instrument would you use?

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Measuring Water

• If you wanted to measure 25 grams of water, what
  2 instruments could you use?

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Accuracy vs. Precision

• ACCURACY
• "capable of providing a correct reading or
  measurement.
• A measurement is accurate if it correctly
  reflects the size of the thing being measured.

• PRECISION
• "exact, as in performance, execution, or amount.
• It means repeatable, reliable, getting the same
  measurement each time.

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Try This On-line Activity
http//www.learner.org/channel/courses/learningmat
h/measurement/session2/part_c/accuracy.html
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Measuring volume of a solid by water displacement
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One cubic centimeter One milliliter
Using water displacement, how many milliliters do
you expect the water to raise when the cube is
lowered?
This cubes sides are each 3 cm. What is the
volume of the cube?
27 cubic cm
27 mL
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Thats all folks!

• Time to try some on your own!