Coursework

1. 1
Chapter 2
Measurements and Calculations
Sections 2.5
In these sections you will learn about:
• English, Metric and SI units
• Prefixes used for smaller and larger measurements.
• Measurements of Length, Volume and Mass

2. 2
Units of Measurements
• In previous parts of this chapter, you learned that the
measurements are Quantitative observations.
• The Units part of a measurement tells us what scale or
standard is being used. The number part tells us how
much the object measured.
• Different systems of measurements are used in
different parts of the world in daily lives.
• English System: In daily lives in USA (inches, feet,
ounce and so on)

3. 3
Units of Measurements
• In 1960, an International System (SI) was set up as a
comprehensive system for scientific work for all
international usage.
• The SI units are based on the metric system.
• However, in USA, in the scientific labs the metric
system is widely used.
• Metric systems units are based on power of 10 and
easier for conversions.

4. 4
Amount of a chemical substance Mole mol
Memorize this Table!!
For metric system, mass unit is grams and
temperature unit is degree Celsius ( C); Length
is meter and time is seconds.

5. 5
Commonly used prefixes in the Metric System
• Substances do not always be of the same size or volume
or mass, as the fundamental units.
• They can be larger or smaller than the fundamental unit.
• Hence the metric and SI systems use prefixes, such
as milli, micro, kilo, etc. to change the size of the
unit.
• All units in the metric system are related to the
fundamental unit by a power of 10
• The power of 10 is indicated by a prefix

6. 6
Prefixes for Length as measurement
• For example, for length, fundamental unit is Meter
(m)
• If an object measures 10 times less than a meter, then
it is called decimeter (prefix is deci; symbol d).
• Therefore, the conversion between decimeter and
meter is:
1 dm = 0.1 m or 10-1 m; (because you are trying to
convert a smaller unit to make it look like a bigger unit)
• Or the reverse of it is 1m= 10 dm; because in a big
1 meter, there are 10 smaller decimeters.

7. 7
If an object is 100 times lesser than a meter, then it is
called centimeter = cm.
• Therefore, the conversion is: 1cm = 1/100th of a meter
= 0.01m or 10-2 m. Notice the exponent is negative
sign.
And if you want to express it the reverse way by
converting the big unit meter to centimeter, remember,
meter is big, and centimeter is small by 100 times.
So, 1m has 100cm = 102 cm; notice the exponent now
is positive sign.

8. 8
Likewise, if an object is 1000 times lesser than a meter,
then it is called millimeter = mm.
• Therefore, the conversion is: 1mm = 0.001m or 10-3
m
• And 1m = 1000mm = 103 mm
If an object is million times lesser than a meter, the it is
called micrometer = uM
• Therefore, the conversion is: 1um = 10-6 m; or 1m =
106 um

9. 9
So, far you saw how to express quantities lesser than the
fundamental unit.
Now, let us see how to express quantities that are bigger than
the fundamental unit.
If an object is 1000 times greater than a meter, then it is called
kilo meter. So, 1km has 1000 meters
• Therefore, the conversion is: 1km = 1000 m= 103m; or 1m =
0.001 km = 10-3 km
If an object is a million times greater than a meter, then it is
called Mega meter. So, 1Mm has 106 meters
• Therefore, the conversion is: 1Mm = 106m;
And therefore 1m = 10-6Mm

10. 10
• For Mass, grams is the fundamental unit in metric
system. And use the same prefixes and
conversions as before.
 So, we have nanograms, micrograms, milligrams, grams,
kilograms, and so on.
1 decigram (dg) = 0.1 g; or reverse it is: 1g = 10 dg
1 centigram (cg) = 0.01 g; or reverse it is: 1g = 100 cg
1 milligram (mg) = 0.001g; or reverse it is: 1g = 1000mg
1 microgram (ug) = 10-6 g; or reverse is: 1g = 106 ug
1 kilogram (kg) = 1000g; or reverse of it is; 1g = 0.001kg

11. 11
For Volume, Liter is the fundamental unit in metric
system. And use the same prefixes and
conversions as before.
 So, we have nanoliter, microliter, milliliter, deciliter, liter,
and so on.
• 1 deciliter (dL) = 0.1 L; or reverse is: 1L = 10 dL
• 1 centiliter (cL) = 0.01 L; or reverse is: 1L = 100 cL
• 1 milliLiter (mL) = 0.001L; or reverse is: 1L = 1000
mL
• 1 micrometer (um) = 10-6L; or reverse is: 1L = 106 uL

12. 12

13. Practice the following:
• How many nanometers are there in a meter?
• How many micrometers are there in a meter?
• How many millimeters are there in a meter?
• How many centimeters are there in a meter?
• How many meters are there in a kilometer?
• (Study Hint: Remember! It is asking how many of
the smaller units are there in the bigger unit.
Therefore, the exponent is positive). Make a flash-
card of the conversions and refer to it often
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14. Practice the following
• In the previous slides, you showed how many of the
smaller units are in a bigger unit. Therefore, you
multiplied it by positive exponents of 10.
• You will do the reverse when you have to show how a
smaller unit equates to a bigger unit. you will use
negative exponents of 10.
• How do you express nanometers in meter unit?
• How do you express micrometer in meter unit?
• How do you express centimeter in meter unit?
• How do you express millimeter in meter unit?
• How do you express meters in kilometer unit?
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15. Interactive website to practice
Metric Prefixes
• http://www.321know.com/mea.htm
Go to the above site, and click on the active
links under the title Metric System. Then,
when each link opens, scroll down to see
interactive animated quizzes. Practice by
doing these interactive activities.
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16. 16
Volume
• Volume is a 3-dimensional space. Has 3 sides to it, and
each of them to be measured in meters for SI or Metric
unit.
• Since fundamental unit is meter, the volume unit has to
be m x m x m using the fundamental unit of meter for
each side.
• So, volume will be m3 (or cubic meter)
• 1 m3 = 1000 liters

17. 17
Volume
• 1 m3 = 1000 liters
• Next smaller prefix to meter is
decimeter.
• 1 m = 10 decimeters
• Therefore in 3-dimensional
volume units, it will be:
• dm x dm x dm = dm3
• So, 1000 times less in volume
• Hence 1 dm3 = 1 Liter

18. 18
Volume
 We learned, 1 L = 1 dm3
 The next smaller unit is 10 times less than dm, and it is
cm.
 But 1 dm = 10 cm.
 Hence in volume, 10cm x 10cm x 10cm = 103 cm3
 Hence 1L = dm3 = 10cm x 10cm x10cm = 1000 or 103 cm3
 So 1 L = 103 cm3 or 1000 cm
 The cm3 is called 1 milliLiter or 1 mL
 Therefore, there are 1000 mL (or 103 mL) in 1 L.
 Or the reverse of it is 1 mL = 0.001 L
 1 mL = 1 cm3 = cubic centimeter = c.c. They all mean the
same. They are less than a liter by 1000 times.

19. Source: Glenn Izett/U.S. Geological Survey.
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20. 20
Mass
• Mass is the quantity of matter present in an object. We
use a weighing balance to measure the mass.
• Fundamental SI unit = kilogram (kg)
• The prefixes are based on the metric unit gram.
• Commonly measured in grams (g) or milligrams (mg)
 1 kg = 1000 g = 103 g,
 Conversely 1g = 10-3 kg
Likewise, for milligram, there are 1000 mg in a g
1g = 1000mg; or conversely, 1mg = 10-3 g = 0.001g

21. 21

22. Some measuring devices used for length,
volume, and mass
• Length: Meter stick, a one-foot Ruler, measuring
tape, yard-stick
• Volume: Graduated cylinder, volumetric pipette,
burette (these were all shown to you in the lab
videos)
• Mass: Analytical balance, top-loading balance
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23. Measuring Devices
A thermometer is used for measuring temperature, a ruler for length
measurement, a graduated cylinder for volume measurement and a
balance for mass measurement as shown in pictures below.
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4. A balance for
mass measurement
1. A thermometer for
temperature measurement
2. A ruler for length measurement
3. A graduated cylinder for
volume measurement

24. In lab measurements
• In all your lab experiments that involve
measurements, you must:
• Include the appropriate unit next to the number
involving a measurement
• Include the value of the number measured to
appropriate significant figures
• And show the uncertainty value (with the  sign)
as you learned in earlier part of this chapter
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