1. 1
Regents Chemistry
Tyna L. Meeks

2. Measurement 2 What is the PURPOSE of measuring/measurements?
Why is there a need to measure
things?
2) Is there a need to standardize measurements?
3) Who decides on the standards?

3. Measurement 3
Measurements are so often taken for granted we sometimes do not appreciate the grand importance measurements play in our lives. On a baseline level, measurements fall into the categories of weight, area, volume, length and even temperature. While we look at these various categories as stoic forms of mathematical measurements a closer examination of things we do in everyday life reveals their clear importance… 3

4. Measurement 4
Taking proper medicine…. 4

5. Measurement 5 Taking proper medicine….
If you have an illness (whether serious or minor) you need to take your medicine and take it in the proper amount. If you take too little or too much then you are not going to get the proper benefit from it. 5

6. Measurement 6
Cooking properly. Cooking of all forms is based on proper attention to measurement. 6

7. Measurement 7
Cooking properly. Cooking of all forms is based on proper attention to measurement. Can you bake a chicken at 600 degrees? Well, you can but the results would be pretty catastrophic! Could you may a cup of tea by dipping a tea bag into a teaspoon of warm water? 7

8. Measurement 8
Purchasing clothes. Now, how important could measurements be when selecting clothes?
Playing sports… you really need to be accurate and comes from a clear sense of depth and distance.
Making estimations. Often we do not have an exact answer so we need to make an estimation which is essentially a guess of measurement. 8

9. Measurement 9 Keeping yourself warm or cool. Understanding weight.
Proper use of capacity.
Telling time.
Transportation.
Structure. 9

10. Measurement 10 Standardized Measurements? Subjective Measurement?
Objective Measurement? 10

11. Measurement 11 Standardized Measurements?
Subjective Measurement : an observation which cannot be seen or is describing an idea, thought, or opinion
Objective Measurement : an observation that can be seen, felt, heard, smelled… 11

12. Measurement 12 Standardized Measurements?
Can I interest you in a grave of chocolate?
Perhaps a piece of land, 2 square smoots? 12

13. Measurement 13 Standardized Measurements?
Can I interest you in 1000 lbs of chocolate?
Perhaps a piece of land, 2 square Harvard Bridges? 13

14. Measurement 14 Standardized Measurements?
Can I interest you in a grave of chocolate?
Perhaps a piece of land, 2 square smoots?
International Union of Pure and Applied Chemistry…
IUPAC 14

15. Measurement 15
Metric System
K H D u d c m
Base Units
Derived Units 15

16. Base Units
This list has the current definitions of each of the seven base units…
Length - Meter ( m )
Mass - Kilogram ( kg )
Time - Second ( s )
Electric Current - Ampere ( A )
Temperature - Kelvin ( K )
Amount of a Substance - Mole ( mol )
Luminous Intensity - candela ( cd )

17. Derived Units
This list has the current definitions of each of the seven base units…
Pressure - Pascal ( Pa ) – kg/m·s2
Force - Newton ( N ) - m·kg/s2
Energy - Joule ( J ) – kg·m2/s2
Density – g/mL or g/cm3
Volume – m3

18. Quality of Measurements18
How do we know we have good measurements?
What is the difference between accuracy and precision?
2) How do I read instruments to the correct precision?
3) How do I determine how accurate my measurement is? 18

19. Quality of Measurements19
How do we know we have good measurements?
4) What are significant figures?
5) How do I perform order of operations with significant figures? 19

20. Quality of Measurements20 20

21. Quality of Measurements21 21

22. Quality of Measurements22 22

23. Quality of Measurements23 23

24. Quality of Measurements24 24

25. Quality of Measurements25 25

26. Quality of Measurements26 26

27. Quality of Measurements27
Significant Figures
All measurements are inaccurate intrinsically
measured quantities are reported such that the last figure is uncertain…
Precision and Accuracy
Precision - how closely individual measurements agree
Accuracy- how closely the measurements agree with the true value 27

28. Quality of Measurements28
Good Precision
Poor Accuracy
Good Precision
Good Accuracy
Poor Precision
Poor Accuracy 28

29. Quality of Measurements29
Percent Error:
(accepted value - measured value) *100
accepted value 29

30. Factor Label Method 30 How do we convert between units?
How do we convert between prefixes using the metric system?
2) How do we convert between units that are NOT metric? 30

31. Factor Label Method 31 50 mi. 1 hour 5280 ft 12 in. = in
Use Units throughout the calculation (helps “guide” calculation.
Should always yield the proper units
Uses conversion factors
How fast is 50 mph in in/sec.?
50 mi. 1 hour 5280 ft 12 in = in
1 hour 3600 sec. 1 mi. 1 ft sec. 31

32. Factor Label Method 32
Determine the length in kilometers of a mi automobile race, knowing that 1.61 km equals 1 mile 32