1. SCIENTIFIC MEASUREMENT
CHAPTER 3
SCIENTIFIC MEASUREMENT

2. QUALITATIVE MEASUREMENTS
GIVE RESULTS IN A DESCRIPTIVE, NON-NUMERIC FORM:
hot cold
big little
heavy light
short tall
QUALITATIVE MEASUREMENTS ARE OFTEN INFLUENCED BY THE MEASURER’S PERCEPTION.

3. QUANTITATIVE MEASUREMENTS
GIVE RESULTS IN A DEFINITE FORM, TYPICALLY A NUMBER WITH UNITS:
100 °C 32 °F
10 gal. 30 ml
11.4 g/cm g/m3
10 ft. 3 ft.
A QUANTITATIVE MEASUREMENT IS ONLY AS ACCURATE AS THE INSTRUMENT AND METHOD USED TO TAKE THE MEASUREMENT.

4. INTERNATIONAL SYSTEM of UNITS
Units of Measurement
Quantity
SI base unit or derived unit
Symbol
Length
meter m
Volume
cubic meter m3
Mass
kilogram kg
Density
grams per cubic centimeter
g/cm3
Temperature
kelvin K
Time
second s
Pressure
pascal Pa
Energy
joule J
Amount of Substance
mole
mol
Luminous Intensity
candela cd
Electric Current
ampere a

5. ACCURACY and PRECISION
ACCURACY – MEASURE OF CLOSENESS TO TRUE VALUE
PRECISION – THE CLOSENESS IN A SERIES OF MEASUREMENTS

6. SIGNIFICANT FIGURES (SF’s)
SF’s INCLUDE ALL KNOWN DIGITS PLUS 1 LAST DIGIT THAT IS ESTIMATED.
CALCULATED VALUES DEPEND ON SF’s IN VALUES USED IN CALCULATION.

7. 2007 and 15.08 both have 4 SF’s SIGNIFICANT FIGURES
WHAT ARE SIGNIFICANT?
EVERY NON-ZERO DIGIT
ZEROS BETWEEN NON-ZERO NUMBERS
2007 and both have 4 SF’s

8. 41.00 and 10.60 each have 4 significant figures.
WHAT ARE SIGNIFICANT?
ZEROS AT THE END OF A NUMBER & ARE AFTER A DECIMAL POINT
41.00 and each have 4 significant figures.

9. Number of red M&M’s SIGNIFICANT FIGURES WHAT ARE SIGNIFICANT?
EXACT NUMBERS HAVE UNLIMITED SF’s.
Number of red M&M’s

10. SIGNIFICANT FIGURES WHAT ARE NOT SIGNIFICANT?
ZEROS IN FRONT OF NON-ZERO NUMBERS
ZEROS AT THE END OF A NUMBER WITHOUT A DECIMAL POINT
and 650,000 each have 2 significant figures.

11. ADD and SUBTRACT SIGNIFICANT FIGURES
ANSWER MUST HAVE SAME NUMBER OF DECIMAL PLACES AS THE VALUE WITH THE LEAST NUMBER OF DECIMAL PLACES

12. ADD and SUBTRACT SIGNIFICANT FIGURES 57.7456 4 decimal places
need to round to decimal places:
59.585

13. SIGNIFICANT FIGURES 17.57 m + 8.4 m + 13.675 m = ?
14 cm cm cm = ?
13.2 Pa– 1.25 Pa = ?
273.5oK – 26.5oK = ?

14. MULTIPLY & DIVIDE SIGNIFICANT FIGURES
ANSWER MUST HAVE THE SAME NUMBER OF SF’s AS THE VALUE WITH THE LEAST NUMBER OF SF’s

15. MULTIPLY & DIVIDE 15.375 ÷ 5.0 = 3.075 5 2 SIGNIFICANT FIGURES
NUMBER OF SF’s
ROUND TO 3.1

16. SIGNIFICANT FIGURES 8.654 m x 0.34 m = ? 2.10 cm x 0.50 cm = ?
ml ÷ 8.4 ml = ?
0.365 m ÷ m = ?

17. SCIENTIFIC NOTATION IS USED TO HANDLE THE RANGE OF VALUES
NUMBERS & MEASUREMENT
CHEMISTRY INVOLVES ACCURATE MEASUREMENTS THAT RANGE FROM VERY LARGE TO VERY SMALL
SCIENTIFIC NOTATION IS USED TO HANDLE THE RANGE OF VALUES

18. SCIENTIFIC NOTATION VALUES ARE WRITTEN AS A PRODUCT OF 2 NUMBERS
COEFFICIENT – VALUE BETWEEN 1 & 10
EXPONENT - 10 RAISED TO A POWER
THE EXPONENT INDICATES THE NUMBER OF TIMES THAT THE COEFFICIENT IS MULTIPLIED OR DIVIDED BY 10

19. SCIENTIFIC NOTATION 175.983 0.9600000 3.65 x 10-3 7.5 x 106
WHAT ARE THESE VALUES IN SCIENTIFIC NOTATION?
6,954,
WHAT ARE THESE VALUES IN STANDARD NUMERICAL FORM?
3.65 x x 106
1.865 x x 10-5

20. MULTIPLY COEFFICIENTS
SCIENTIFIC NOTATION
MULTIPLICATION
MULTIPLY COEFFICIENTS
ADD EXPONENTS
7.2 x 102 · 5.02 x = ?
1.0 x 102 · 2.6 x 108 = ?

21. SUBTRACT EXPONENT OF DENOMINATOR FROM EXPONENT OF NUMERATOR
SCIENTIFIC NOTATION
DIVISION
DIVIDE COEFFICIENTS
SUBTRACT EXPONENT OF DENOMINATOR FROM EXPONENT OF NUMERATOR
8.4 x 103 / 2.1 x 10-2 = ?
7.25 x 104 / 5.0 x 102 = ?

22. ADDITION & SUBTRACTION
SCIENTIFIC NOTATION
ADDITION & SUBTRACTION
ADJUST EXPONENT OF BOTH NUMBERS TO BE SAME
ADJUST COEFFICIENT TO REFLECT CHANGE IN EXPONENT
PERFORM OPERATION AND READJUST ANSWER TO PROPER SCIENTIFIC NOTATION

23. SCIENTIFIC NOTATION 7.563 x 102 - 1.77789 x 10-3 = ?

24. DENSITY Which is heavier – a pound of popcorn or a pound of cheese?
They would have the same mass!!
However, if you had equal VOLUMES of popcorn and cheese, the cheese would have more mass.

25. IS IT MORE OR LESS DENSE THAN WATER?
SPECIFIC GRAVITY
SPECIFIC GRAVITY (Sp.G.) COMPARES THE DENSITY OF 1 MATERIAL TO THE DENSITY OF WATER.
DENSITY OF 4o C = 1 g/cm3, AND IS USED AS A REFERENCE.
LIQUID SPECIFIC GRAVITY IS MEASURED BY A HYDROMETER.
IF Sp.G. OF WOOD = 0.5,
IS IT MORE OR LESS DENSE THAN WATER?

26. THE TEMPERATURE OF AN OBJECT DETERMINES THE FLOW OF HEAT TRANSFER
HOTTER COOLER
CELCIUS (CENTIGRADE) scale uses the freezing point of water as 0oC and the boiling point of water as 100oC.
KELVIN scale uses 273oK for the freezing point of water, and 373oK as the boiling point.