1. PRINCIPLES OF CHEMISTRY I CHEM 1211 CHAPTER 1
DR. AUGUSTINE OFORI AGYEMAN
Assistant professor of chemistry
Department of natural sciences
Clayton state university

2. CHAPTER 1 MEASUREMENT

3. MEASUREMENT
- Is the determination of the dimensions, capacity, quantity,
or extent of something
- Is a quantitative observation and consists of
two parts: a number and a scale (called a unit)
- Is the tool chemists use most
Examples
mass, volume, temperature, pressure, length, height, time

4. SIGNIFICANT FIGURES Precision
- Provides information on how closely individual
(repeated) measurements agree with one another
Accuracy
- Refers to how closely individual measurements
agree with the true value (correct value)
Precise measurements may NOT be accurate

5. SIGNIFICANT FIGURES Exact Numbers - Values with no uncertainties
- There are no uncertainties when counting objects or people
(24 students, 4 chairs, 10 pencils)
- There are no uncertainties in simple fractions
(1/4, 1/7, 4/7, 4/5)
Inexact Numbers
- Associated with uncertainties
- Measurement has uncertainties (errors) associated with it
- It is impossible to make exact measurements

6. SIGNIFICANT FIGURES Measurements contain 2 types of information
- Magnitude of the measurement
- Uncertainty of the measurement
Only one uncertain or estimated digit should be reported
Significant Figures
digits known with certainty + one uncertain digit

7. RULES FOR SIGNIFICANT FIGURES
1. Nonzero integers are always significant
4732 (4 sig. figs.) 875 (3 sig. figs.)
2. Leading zeros are not significant
(2 sig. figs.) (4 sig. figs.)
The zeros simply indicate the position of the decimal point
3. Captive zeros (between nonzero digits) are always significant
(5 sig figs.) (8 sig figs)

8. RULES FOR SIGNIFICANT FIGURES
4. Trailing zeros (at the right end of a number) are significant
only if the number contains a decimal point
(5 sig figs) (3 sig figs)
5. Exact numbers (not obtained from measurements) are assumed
to have infinite number of significant figures

9. RULES FOR SIGNIFICANT FIGURES
How many significant figures are present in each of the following?
What is the uncertainty in each case?
significant figures uncertainty
1.24 g ± 0.01 g
L ± L
mL ± mL
kg ± kg

10. RULES FOR SIGNIFICANT FIGURES
Rounding off Numbers
1. In a series of calculations, carry the extra digits through
to the final result before rounding off to the required
significant figures
2. If the first digit to be removed is less than 5, the
preceding digit remains the same (round down)
Round to two significant figures
2.53 rounds to and rounds to 1.2

11. RULES FOR SIGNIFICANT FIGURES
Rounding off Numbers
3. If the first digit to be removed is greater than 5, the
preceding digit increases by 1 (round up)
(2.56 rounds to and rounds to 1.3)
4. If the digit to be removed is exactly 5 (round even)
- The preceding number is increased by 1 if that
results in an even number
(2.55 rounds to and rounds to 1.4)
- The preceding number remains the same if that
results in an odd number
(2.45 rounds to and rounds to 1.2)

12. RULES FOR SIGNIFICANT FIGURES
- The certainty of the calculated quantity is limited by the least
certain measurement, which determines the final number of
significant figures
Multiplication and Division
- The result contains the same number of significant figures as the
measurement with the least number of significant figures
x 4.02 = = 8.22
÷ 1.2 = = 2.7

13. RULES FOR SIGNIFICANT FIGURES
- The certainty of the calculated quantity is limited by the least
certain measurement, which determines the final number of
significant figures
Addition and Subtraction
- The result contains the same number of decimal places as the
measurement with the least number of decimal places
= 4.03
= 6.00 (not 6)
= 5.5

14. SCIENTIFIC NOTATION
- Used to express too large or too small numbers (with many zeros)
in compact form
- The product of a decimal number between 1 and 10 (the coefficient)
and 10 raised to a power (exponential term)
24,000,000,000,000 = 2.4 x 1013
exponent (power)
coefficient
exponential term
= 4.58 x 10-7

15. SCIENTIFIC NOTATION
- Provides a convenient way of writing the required
number of significant figures
to 4 significant figures = x 106
2400 to 3 significant figures = 2.40 x 103
to 2 significant figures = 3.0 x 10-4

16. SCIENTIFIC NOTATION - Add exponents when multiplying exponential terms
(5.4 x 104) x (1.23 x 102)
= (5.4 x 1.23) x
= 6.6 x 106
- Subtract exponents when dividing exponential terms
(5.4 x 104)/(1.23 x 102)
= (5.4/1.23) x
= 4.4 x 102

17. MEASUREMENT SYSTEMS Two measurement systems:
English System of Units (commercial measurements):
pound, quart, inch, foot, gallon
Metric System of Units (scientific measurements)
SI units (Systeme International d’Unites)
liter, meter, gram
More convenient to use

18. FUNDAMENTAL (BASE) UNITS
Physical Quantity
Mass
Length
Time
Temperature
Amount of substance
Electric current
Luminous intensity
Name of Unit
Kilogram
Meter
Second
Kelvin
Mole
Ampere
Candela
Abbreviation kg m
s (sec) K
mol A cd

19. DERIVED UNITS Area = length x length = m x m = m2
Volume = m x m x m = m3
Volume may also be expressed in LITERS (L)
1L = 1000 mL = 1000 cm3 or cubic centimeters (c.c.)
Implies 1mL = 1c.c.
mL is usually used for volumes of liquids and gases
c.c. is usually used for volumes of solids
Density = kg/ m3

20. DERIVED UNITS Physical Quantity Force Pressure Energy Power Frequency
Name of Unit
Newton
Pascal
Joule
Watt
Hertz
Abbreviation
N (m-kg/s2)
Pa (N/m2; kg/(m-s2)
J (N-m; m2-kg/s2)
W (J/s; m2-kg/s3)
Hz (1/s)

21. UNIT CONVERSIONS Prefix Abbreviation Notation Giga Mega Kilo Deci
Centi
Milli
Micro
Nano
Pico
Femto
Abbreviation G M k d c m n p f
Notation
109
106
103
10-1
10-2
10-3
10-6
10-9
10-12
10-15

22. UNIT CONVERSIONS 1 gigameter (Gm) 1 megameter (Mm) 1 kilometer (km)
1 decimeter (dm)
1 centimeter (cm)
1 millimeter (mm)
1 micrometer (µm)
1 nanometer (nm)
1 picometer (pm)
1 femtometer (fm)
= 109 meters
= meters
= meters
= meter
= meter
= meter
= meter
= meter
= meter
= meter

23. UNIT CONVERSIONS Length/Distance 2.54 cm = 1.00 in. 12 in. = 1 ft
1 yd = 3 ft
1 m = 39.4 in.
1 m = 1.09 yd
1 km = mile
1 km = 1000 m
Time
1 min = 60 sec
1 hour = 60 min
24 hours = 1 day
7 days = 1 week
Volume
1 gal = 4 qt
1 qt = L
1 L = 1.06 qt
1 L = gal
1 mL = fl. oz.
Mass
1 Ib = 454 g
1 Ib = 16 oz
1 kg = 2.20 lb
1 oz = 28.3 g

24. UNIT CONVERSIONS Conversion Factors 1 km = 1000 m » or 1 L = 1000 mL »
24 hours = 1 day
1 kg = 2.20 lb or

25. UNIT CONVERSIONS given number · unit new unit = new number · new unit
unit to be converted
quantity to be
expressed in
new units
quantity now
expressed in
new units
conversion factor
given data
desired unit
= answer in desired unit
unit of given data

26. UNIT CONVERSIONS Convert 34.5 mg to g
How many gallons of juice are there in 20.0 liters of the juice?
Convert 4.0 gallons to quarts

27. UNIT CONVERSIONS Convert 2.64 μg to kg Convert 3.912 m2 to km2
Convert 4.0 cm3 to μm3

28. DENSITY - The amount of mass in a unit volume of a substance Density =
Ratio of mass to volume =
Units
Solids: grams per cubic centimeter (g/cm3)
Liquids: grams per milliliter (g/mL)
Gases: grams per liter (g/L)
- Density of 2.3 g/mL implies 2.3 grams per 1 mL
- Density usually changes with change in temperature

29. DENSITY For a given liquid:
- Objects with density less than that of the liquid will float
- Objects with density greater than that of the liquid will sink
- Objects with density equal to that of the liquid will remain
stationary (neither float nor sink)

30. DENSITY The liquid level in a graduated cylinder reads 12.20 mL.
The level rises to mL when g of piece of
gold is added to the cylinder. What is the density of gold?
Volume of the piece of gold = mL – mL = 6.70 mL
Mass of the piece of gold = g
Density = mass/volume
= g/6.70 mL = 19.3 g/mL or 19.3 g/cm3

31. TEMPERATURE
- The degree of hotness or coldness of a body or environment
3 common temperature scales
Metric system: Celsius and Kelvin
English system: Fahrenheit
Celsius Scale (oC): Reference points are the boiling and freezing
points of water (0oC and 100oC) degree interval
Kelvin Scale (K): Is the SI unit of temperature (no degree sign)
The lowest attainable temperature on the Kelvin scale is 0
(-273 oC) referred to as the absolute zero

32. TEMPERATURE Fahrenheit Scale: Water freezes at 32oF and boils at 212oF
- 180 degree interval or or
10o, 40o, 60o may be considered as 2 significant figures
100o may be considered as 3 significant figures

33. TEMPERATURE Convert 29 oC to K Convert 29 K to oC Convert 29 oF to oC
Convert 29 oC to oF