units of measurement
DESCRIPTION
Meter m Liter L Celsius C. Units of Measurement. Mass is the amount of matter, weight is a measure of the gravitational pull on matter. SI Units. Practice In each pair below, circle the larger. Basic SI Units. Metric Conversion. - PowerPoint PPT PresentationTRANSCRIPT
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Units of MeasurementMeter m
Liter L
Celsius C
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Mass is the amount of matter, weight is a measure of the gravitational pull on matter
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SI UnitsPrefix Symbol Scientific
notationFactor Example
Mega M 1 x 106 1,000,000 megagram (Mg)
Kilo k 1 x 103 1,000 kilometer (km)
Hecto h 1 x 102 100 hectoliter (hL)
Deka da or (D) 1 x 101 10 dekagram (Dg)
BASE UNIT 1 x 100 1 meter
Deci d 1 x 10-1 .1 deciliter (dL)
Centi c 1 x 10-2 .01 centimeter (cm)
Milli m 1 x 10-3 .001 milligram (mg)
Micro u 1 x 10-6 .000001 microgram (ug)
Nano n 1 x 10-9 .000000001 nanometer (nm)
Pico p 1 x 10-12 .000000000001 picogram (pg)
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PracticeIn each pair below, circle the larger
Millimeter Centimeter
picometer Micrometer
kilogram Hectogram
deciliter millileter
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Basic SI UnitsQuantity Base unitLength meter (m)Mass gram (g)Time second (s)Volume Liter (L)Temperature Kelvin (K) or Celsius (C)Amount of substance mole (mol)Heat & Energy joule (J)
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Metric Conversion
1.) 3.45 cm= Dm
king henry Died by drinking chocolate milkK h D base d c m
0.00345
243.52.) 2.435 g= cg
2.35
3.) 23.8 mL= L
4.) 14.8 km= m
5.) 23.5 cg= dg
0.0238
14800
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TemperatureUse both the Kelvin and Celsius scale, to convert
Celsius + 273 = Kelvin
Kelvin -273 = Celsius
373 K = °C
20°C = K293
100
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Volume: measured in cubic centimeters (cm3) or liters
• 1 liter (L) = 1 cubic decimeter (dm3) = 1000 millileters (mL)• 1 mL= 1 cm3
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• Volume can be measure by Length x x or the Water Displacement method
width height
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• Volume can be measure by Length x width x height or the Water Displacement method
Know the relationship between the following volume units…
L = mL = cm3 (or cc in medical lingo) 1 1000 1000
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Density
• Is the ratio of mass per unit of volume. How much matter is packed into a given amount of space
• Density = mass ÷ volume
• D= M V
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• The Density of a substance stays regardless of the size of the sample. For example: if you cut a block of copper in half, you have decreased both the mass and volume, the ratio of the 2 stays the same. This is called an Intensive Physical Property.
Constant
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• The appropriate units of density are:
• for solids• for liquids
g/cm3
g/mL
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Example problems:
• A sample of aluminum metal has a mass of 8.4g. The volume of the sample is 3.1 cm3. Calculate the Density of aluminum.
D = M =V
8.4 3.1
=2.7 g/cm3 2 sig figs
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Example problems:
• Diamond has a density of 3.26 g/cm3. What is the mass of a diamond that has a volume of 0.350 cm3?
D = 3.26 g/cm3
M = ? V = 0.350 cm3
D = M V
3.26 g/cm3 x 0.350 cm3 = 1.14 g3 sig figs
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Example problems:
• What is the volume of a sample of liquid mercury that has a mass of 76.2 g, given that the density of mercury is 13.6 g/mL?
V = ? M = 76.2 g D = 13.6 g/mL
D= MV
76.2 g 13.3 g/mL = 5.7293 mL = 5.73 mL
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Reliable Measurements
• refers to the closeness of the measure value is to the , or real, value.
• refers to how a series of measurements are to one another.
Accuracy
Actual
Precision Close
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• is calculated by subtracting the value from the value.
ErrorExperimental accepted
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• The is the ratio of an error to an accepted value.
percent error
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% error = error x 100 = accepted value – experimental value x 100 accepted value accepted value
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Example
• An experiment finds the density of lead to be 10.95 g/cm3. The literature value for the density of lead is 13.34 g/cm3.
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The error: accepted value – experimental value=
• 13.34 – 10.95 =
An experiment finds the density of lead to be 10.95 g/cm3. The literature value for the density of lead is 13.34 g/cm3.
2.39
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The error: accepted value – experimental value=• 13.34 – 10.95 = 2.39
The % error: error x 100 % = accepted value
2.39 x 100 % =13.34
17.9 %
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Practice
• Sara’s lab shows the atomic mass of aluminum to be 28.9. What is her percent error if the accepted value is 27.0?
28.9 – 27.0 = 1.90
7.04%1.90/27.0 x 100% =
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Practice
• What is the percent error in a measurement of the boiling point of bromine if the textbook value is 60.8 °C and the lab value is 40.6 °C?
60.8 °C – 40.6 °C = 20.2 °C
20.2 °C / 60.8 °C x 100% = 33.2%