chapter 2 – section 2 suggested reading pages 33-42 units of measurement
TRANSCRIPT
![Page 1: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/1.jpg)
Chapter 2 – Section 2
Suggested Reading
Pages 33-42
Units of Measurement
![Page 2: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/2.jpg)
Making Measurements
Measurements must have a number and a unit.
The unit depends on the quantity being measured.
![Page 3: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/3.jpg)
SI Measurement
Le Systeme International d’Unites
See Table of SI Base units – Page 34
See Table of SI Prefixes – Page 35
![Page 4: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/4.jpg)
Standard SI Units
Length = meter (m)
Mass = kilogram (kg)
Time = second (s)
Temperature = Kelvin (K)
Amount of substance = mole (mol)
![Page 5: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/5.jpg)
Derived SI Units
Area = square meter (m2)
Volume = cubic meter (m3)
Density = kilograms per cubic meter (kg/m3)
Produced by multiplying or dividing standard units.
![Page 6: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/6.jpg)
Definitions
Mass – a measure of the quantity of matter in an object.
Weight – a measure of the gravitational pull on matter.
Volume – the amount of space occupied by an object.
Density – the ratio of mass to volume
![Page 7: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/7.jpg)
The density of an object is calculated by
dividing the mass of the object by its volume.
Density
The object with the lowest density will float.
![Page 8: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/8.jpg)
Density is a Derived Unit
Combination of base units
Mass (g or kg)
Volume (m3 or cm3) length length length
D = MV
1 cm3 = 1 mL1 dm3 = 1 L
Density (kg/m3 or g/cm3 or g/mL)
mass per volume
![Page 9: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/9.jpg)
DensityM
ass
(g)
Volume (cm3)
Δx
Δyslope D
V
M
![Page 10: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/10.jpg)
Density
An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.
GIVEN:
V = 825 cm3
D = 13.6 g/cm3
M = ?
WORK:
M = DV
M = (13.6 g/cm3)(825cm3)
M = 11,200 g
V
MD We will talk about
how to round correctly soon!
![Page 11: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/11.jpg)
Density
A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid?
GIVEN:
D = 0.87 g/mL
V = ?
M = 25 g
WORK:
V = M D
V = 25 g
0.87 g/mL
V = 29 mLV
MD
![Page 12: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/12.jpg)
Dimensional Analysis –
The technique of converting between units.
![Page 13: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/13.jpg)
Six Steps that May Help You:
1. Write down the starting number with unit, draw a horizontal line under it, and a vertical line next to it.
![Page 14: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/14.jpg)
2. Look at the unit and write down conversion factors that might work. (You have to THINK of these.)
3. Write down UNITS for conversion factors ABOVE & BELOW the line so the unit you started with will CANCEL OUT.
![Page 15: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/15.jpg)
4. Fill in the numbers that go with the conversion factors.
6. Do the math & don’t forget to round correctly at the end & put the correct unit on your final answer.
5. Cancel out units as required.
![Page 16: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/16.jpg)
Example:
1. Write it down, draw the lines.
14 cm
Convert 14 cm to meters
![Page 17: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/17.jpg)
Example:
14 cm
Convert 14 cm to meters
2. Write down the factor.
Our factor that we think will work is 100 cm = 1 meter
![Page 18: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/18.jpg)
Example:
14 cm
Convert 14 cm to meters
Conversion Factor: 100 cm = 1 meter
3. Fill in the units from the factor so that the starting unit will cancel out.
cm
m
![Page 19: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/19.jpg)
Example:
14 cm
Convert 14 cm to meters
Conversion Factor: 100 cm = 1 meter
cm
m
4. Fill in the numbers from the conversion factor.
100
1
![Page 20: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/20.jpg)
Example:
14 cm
Convert 14 cm to meters
Conversion Factor: 100 cm = 1 meter
cm
m
100
1
5. Cancel out units.
![Page 21: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/21.jpg)
Example:
14 cm
Convert 14 cm to meters
cm
m
100
1
6. Do the math.
Multiply all numbers across the top, divide by each number across the bottom.
= 14 100
= 0.14 mDon’t forgetunits!
1x
![Page 22: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/22.jpg)
Example: Convert 4.7 kg to pounds
Some Problems Require Many Steps …Just draw a longer line!
![Page 23: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/23.jpg)
Example:
1. Write it down, draw the lines.
4.7 kg
Convert 4.7 kg to pounds
![Page 24: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/24.jpg)
Example:
4.7 kg
2. Write down the factors.
Our factors that we think will work are 454 g = 1 lb 1000g = 1 kg
Convert 4.7 kg to pounds
![Page 25: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/25.jpg)
Example:
4.7 kg
Conversion Factors: 454 g = 1 lb and 1000g = 1 kg
3. Fill in the units from the factors so that the starting unit will cancel out.
kg
g
Convert 4.7 kg to pounds
g
lb
![Page 26: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/26.jpg)
Example:
4.7 kg
4. Fill in the numbers from the conversion factors.
1
1000
Convert 4.7 kg to pounds
Conversion Factors: 454 g = 1 lb and 1000g = 1 kg
g
kg
lb
g
1
454
![Page 27: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/27.jpg)
Example:
4.7 kg
1
1000
Convert 4.7 kg to pounds
Conversion Factors: 454 g = 1 lb and 1000g = 1 kg
g
kg
lb
g
1
454
5. Cancel out units.
![Page 28: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/28.jpg)
*Example:
4.7 kg
1
1000
Convert 4.7 kg to pounds
g
kg
lb
g
1
454
6. Do the math.
Multiply all numbers across the top, divide by each number across the bottom.
=
=
Don’t forgetunits!
10. lb4.7 x 1000 x 1 1 454
![Page 29: Chapter 2 – Section 2 Suggested Reading Pages 33-42 Units of Measurement](https://reader036.vdocument.in/reader036/viewer/2022081506/56649eeb5503460f94bfc6d1/html5/thumbnails/29.jpg)
How to measure
Mass – balance
Weight – a spring scale
Volume – volumetric flask