CHEM 1211 PRINCIPLES OF CHEMISTRY I

1
CHEM 1211 PRINCIPLES OF CHEMISTRY I

• By
• Dr. Barry Miburo.

2
Chapter 1. Fundamental Concepts

• Objectives
• Describe the forms, composition properties of
  matter
• Perform calculations on measurement results
  following the rules of significant figures and
  dimensional analysis.
• Case Study burning wood

3
Analysis of the contents of the solids

• 1. Composition
• Before burning
• Carbon, Hydrogen, Oxygen
• After burning
• Carbon
• Other substances detected water (gas)
• 2. Comparison of identities of substances same
  or changed?

4
1.1. Chemistry Overview

• Definition
• Chemistry Study of
• composition, structure, and properties of
  substances (matter)
• transformations of substances from one to
  another.

5
b. Substance (matter)

• Any entity that has volume and weight.
• Examples
• Charcoal. Basic component one particle,
  carbon
• Water. Basic component an assembly of 3
  particles one oxygen, two hydrogens.
• http//images.google.com/images?hlenrlsGWYG,GWY
  G2006-30,GWYGenqwatermoleculeum1ieUTF-8
• You?
• Light? See RQ2-1

6
Running Quiz Question 1

• Is light a substance?
• a. Yes, because light has energy (sunlight can
  burn you)
• b. No, because light has no mass (sunlight can
  burn you)
• c. Yes, because light has a volume (sunlight can
  burn you)

7
Types of substances

• 1. Elements made of identical atoms
• Atom the smallest particle that can form a
  substance.
• Charcoal made of carbon atoms
• Aluminum foil made of aluminum atoms.
• Your own examples?

8
2. CompoundsSubstances made of molecules

• Molecule an assembly of atoms that is used to
  build a substance
• Water an assembly of two hydrogens and one
  oxygen atoms
• Salt an assembly of one sodium and one chlorine
  atoms
• Your own examples? See RQ2-2

9
RQ2-2

• Is a mixture of iron and charcoal powders an
  example of a compound?
• a. No, because it is an element.
• b. Yes, because it is a mixture of two elements
  that can be separated
• c. No, because it is a mixture of two elements
  that can be separated

10
c. Composition and Structure

• Composition building blocks of a substance
• http//en.wikipedia.org/wiki/ImageBrick_likn_indi
  a.JPG
• Structure arrangements of building blocks inside
  a substance
• http//en.wikipedia.org/wiki/ImageFlemish_Bond.jp
  g

11
d. Transformations.

• Criterion comparison of substance identity
  before after transformation.
• 1 Chemical change Chemical reaction
• Substance identity after the transformation
  different from identity before the transformation
  
• Ex
• Iron rusting
• Your own example?

12
2. Physical Transformation

• Substance identity stays the same
• Ice melting
• Chemical formula
• Ice H2O
• Water H2O
• Drying clothes
• Gas burning?
• RQ2-3

13
RQ2-3

• Which part of burning a candle is a chemical,
  which one is a physical change?
• a. Candle wax melting and wick burning are both
  physical changes.
• b. Candle wax melting is a physical change and
  candle wick burning is a chemical change.
• c. Candle wax melting is a chemical change and
  candle wick burning is a physical change.

14
FYIBranches of Chemistry

• Analytical studies composition structure of
  substances
• Organic studies composition structure and
  transformations of carbon based substances
• Inorganic studies composition structure and
  transformations of non-carbon based substances
• Physical Studies microscopic properties of
  substances

15
1.2. Classification of Substances

• Thought teasers Compare and tell the difference
  between
• Orange juice (O. J.) apple juice (A. J.) by
  simple eye exam
• Apple juice water by evaporation
• Water aluminum foil by breaking them down to
  components

16
Classification of Substances
17
(No Transcript)
18
(No Transcript)
19
RQ2-4

• Examine the previous graphic and identify which
  picture shows which one of the following the
  types of substances an element, a compound, a
  homogeneous or a heterogeneous mixture?
• a. Element d, Compound a, homogenous mixture
  c, heterogeneous mixture b
• b. Element a, Compound b, homogenous mixture
  c, heterogeneous mixture d
• c. Element b, Compound a, homogenous mixture
  c, heterogeneous mixture d

20
1.3. Measurement Calculations

• Thought teasers what questions come to your mind
  if you are told
• You have 176
• You can drive this baby home for less than
  20,000

21
a. Overview

• 1. Measure
• Definition The quantitative evaluation of a
  property
• Example
• 176 cm. Measured property length
• other examples?

22
Components of a Measure

• Example 176 cm
• Questions answered
• How much?
• What?
• Magnitude how large or small?
• Accuracy range of measuring instrument
• Units conventional quantitative reference used
  to describe a property in measurement

23
2. Measurement Standard

• Definition Set of accepted units used in
  measurement
• SI (metric) system standard for scientific
  measurement
• Property Unit Abbreviation
• Length meter m
• Mass gram g
• Amount
• of substance mole mol
• Time second s
• Temperature Kelvin K
• More units Table 1.1, pg 16

24
RQ2-5

• Are mass and amount of substance identical or
  different properties? Explain.
• a. Different. Mass tells how many building blocs
  substance has. Amount of substance tells if a
  substance is heavy or light.
• b. Identical. Mass tells if a substance is heavy
  or light. Amount of substance tells how many
  building blocs a substance has.
• c. Different. Mass tells if a substance is heavy
  or light. Amount of substance tells how many
  building blocs a substance has.

25
3. Prefixes

• Definition Prefix Multiple of the basic unit
• Originally designed to express very small and
  very large measures using shorter numbers
• Example 0.000000001 m 1nm
• n nano prefix, multiplies base unit (m) by
  1/1000000000 or 10-9 or 1E-9

26
Some Prefixes (Table 1.2, pg 19)

• Prefix multiplies Example
• (Abbrevn) base unit by
• Giga (G) 1E9 Gbyte
• Mega (M) 1E6 MHz
• Kilo (k) 1E3 Kg
• Deci (d) 1E-1 dm
• Centi (c) 1E-2 cm
• Milli (m) 1E-3 mg
• Micro (m) 1E-6 m m
• Nano (n) 1E-9 ns

27
b. Uncertainty

• Part of a measure that is subject to
• Approximation
• Last digit in a number
• Measure Uncertainty
• 25 L 1L
• 274.9 lb 0.1 lb

28
a. Expressions of UncertaintyPrecision and
Accuracy

• Precision
• Extent of agreement between
• different measures
• Accuracy
• Extent of agreement between
• different measures and the accepted
• value

29
(No Transcript)
30
(No Transcript)
31
(No Transcript)
32
Measure of Uncertainty Error

• Tools needed to determine the error
• Experimental Value EV
• Accepted Value AV
• Error 100 (AV EV) / AV

33
Measure of Uncertainty Illustration

• Melting Point of Aspirin (AV 135 o C)
• Experimental Set 1 2
• 134 138
• 136 137
• 133 138
• 138 138
• Calculate average values and errors
• Indicate the set with highest precision, accuracy

34
A student measures the mass of a penny 4 times
and records the following data. What can be said
about the data if the actual mass of the penny is
2.4987 g?

• a. The data is neither accurate nor precise.
• b. The data is accurate, but not precise.
• c. The data is not accurate, but it is precise.

35
c. Significant Figures (SF)

• Definition Digits of a number that are related
  to measurement
• SFs show the level of uncertainty of a measure.
• Uncertainty is reflected in the last digit of a
  number
• SF Determination
• Count from left to right
• Start from 1st non-zero digit

36
Significant Figures (Illustration)

• Example
• number SF's
• 530 3
• 00530 3
• 0.000530 3

37
Numbers ending in 0's without decimal dot

• SFs depends on the range of the measuring
  instrument
• 1300 g
• Instrument Significant SFs
• range zeros
• Hundreds 0 2
• Tens 1 3
• Ones 2 4

38
RQ2-6. When reading a graduated cylinder, read
the volume at the bottom of the meniscus.

• What volume of liquid is in the graduated
  cylinder?
• 4.5 mL
• 4.6 mL
• 4.56 mL

39
d. Scientific (Exponential) Notation (SN)

• Definition Convention used to write very small
  very large numbers more conveniently
• Features of a number in SN N x 10n
• N digit factor number in the form a.bcd a
  digit from 1 to 9 b, c, d digits from 0 to
  9.
• N shows the number of significant figures.
• 10n exponential factor n exponent whole
  number.

40
SN Writing Procedure

• Write number in normal notation
• Place decimal dot after 1st digit in the number
• Count the number of places the decimal dot must
  move to return to original position.
• Exponent the number of places the dot must move
  
• Positive Exponent if dot is moved to the right
• Negative Exponent if dot is moved to the left
• Examples 0.000009473 2584963170 written with 3
  SFs.

41
RQ2-7

• If you measure 15000 g of sand with a balance
  that weighs down to hundreds of grams, how should
  you report it?
• a. Report it as 15000 g because that is what the
  instrument says.
• b. Report it as 1.50E4 g because on that balance
  the measure is between 14900 and 15100 g and has
  3 SFs.
• c. Report it as 1.5E4 g because on that balance
  the measure is between 14000 and 16000 g and has
  2 SFs.

42
e. Rounding off

• Writing a measure with less digits than the
  original number
• Read pg 25

43
f. Significant Figures in Calculations

• 1. Multiplication Division
• Rule of SF's in final result same as in
  measure with least SF's.
• number SF's
• 12.34 4
• x 2.34 3
• 28.8756 6 in calculations
• 28.9 3 in reported results

44
2. Addition Subtraction

• of digits after the decimal dot in final
  result same as in measure with the fewest
  digits after decimal period.
• Example
• number digits after period
• 9.874 3
• 9.8 1
• 19.674 3 in calculations
• 19.7 1 in reported results

45
g. Perfect (exact) numbers

• 's without uncertainty
• SFs potentially infinite, not counted in
  calculations
• counted whole items.
• eggs, people, cars,
• Defined Quantities
• ex 1 km 0.62137 mi. 1.5172938 km 1.517293 x
  0.62137 mi 0.9428003 mi.

46
Significant Figures in Calculations (Illustration)

• (1.7E6 2.63E5) 7.33 ?
• (944345 9.9) 5.3 ?
• Extra exercise 81, pg 41

47
RQ2-8

• If you use 2.1, 2.1 and 2.3 mL of solution to run
  a chemical reaction, what is the average volume
  of solution used?
• a. 6.5 mL / 3 2.166666666666666667 mL, because
  that is the mathematical result.
• b. 6.5 mL / 3 2.2 mL, because the original
  measure has 2 SFs and 3 is an exact number.
• c. 6.5 mL / 3 2 mL, because the number of SFs
  of a division result is determined by the number
  with the lowest number of SFs.

48
1.4. Conversion of Units Dimensional Analysis

• Any conversion requires a conversion factor
• Conversion Factor(CF) tool used to convert a
  measure from original to target units
• CF Numeric and dimensional relation between
  original and target unit.
• Relation
• Measure in Original unit x CF Measure in Target
  Unit
• CF Measure in Target Unit / Measure in Original
  unit

49
Conversion Factor (Illustration)

• 1 cm 1E-5 km
• CF for cm to km conversion
• 1E-5 km/cm
• CF for Km to cm conversion
• 1E5 cm/km

50
a. Metric system Conversions

• Prefix to Prefix conversion through the base
  unit
• Procedure
• Convert original to base unit. Result CF of
  original to base unit.
• Convert base to final unit. Result CF of base to
  final unit.
• Convert original to final unit through base unit.
  Multiply the two CFs. Result CF of original to
  final unit
• Ex 115 mm ?km

51
Metric system Conversions (Illustration)

• May average rainfall in Tifton 115 mm
• km ?
• CF of mm to m 1 mm 1E-3 m -gt
• CF1 1E-3 m / mm
• CF of m to km 1 km 1E3 m -gt
• CF2 1 km / 1E3 m 1E-3 km/m
• Overall CF CF1 x CF2 1E-3 m/mm x 1E-3 km/m
  1E-6 km/mm
• 115 mm 115 x 1 mm 115 x 1E-6 km
• 1.15E2 x 1E-6 km 1.15E-4 km

52
Numeric Illustration (Shortcut)

• May average rainfall in Tifton 115 mm
• km ?
• 1 mm 1E-3 m (1)
• 1 km 1E3 m -gt 1 m 1E-3 km (2)
• Replace m in relation (1) by its value from
• relation (2)
• 1 mm 1E-3 x 1E-3 km 1E-6 km
• 115 mm 115 x 1 mm 115 x 1E-6 km
• 1.15E2 x 1E-6 km 1.15E-4 km
• Extra exercise 57, pg 40

53
b. Metric-English System conversion

• Find conversion factor used to express one
  original unit into target units
• Multiply the number in original units by
  conversion factor to find the number in target
  units
• Unit Conversion tables see Inner back cover of
  textbook
• Ex 11.5 cm ? In

54
Numeric Illustration

• May average rainfall in Tifton 11.5 cm
• in ?
• From tables 1 in 2.54 cm -gt 1 cm 0.394 in
• 11.5 x 1 cm 11.5 x 0.394 in 4.54 in
• Extra ex 83, pg 41 (b kg ot lb)

55
Numeric Illustration (2)

• A jogger runs at an average speed of 5.9 mi/h.
  How fast does she run in m/s?
• From tables
• 1 mi 5280 ft
• 1 m 3.281 ft -gt 1 ft 0.3048 m
• 1 mi 5280 x 0.3048 m ? m
• 1 h 3600 s
• 5.9 mi/h 5.9 x ? m / 3600 s ? m/s
• Extra Exercise 87, pg 41

56
Extra Exercise

• The non-SI unit, the hand (used by equestrians),
  is 4 inches. What is the height in meters, of a
  horse that stands 15 hands high?
• Convert hands to ins to cms to ms

57
RQ2-9

• If you convert a measure from a large to small
  unit, what happens to the magnitude of the
  measure?
• a. It decreases, because it takes a larger number
  of smaller units to match a larger unit.
• b. It increases, because it takes a larger number
  of smaller units to match a larger unit.
• c. It increases, because it takes a smaller
  number of smaller units to match a larger unit.

58
c. Fahrenheit - Celsius Temperature Conversions

• Read pg 17
• Problem The average May temperature in Tifton is
  83.8 oF. What is the temperature in Kelvins?
• Challenge Calculate the temperature that is the
  same both in Celsius and Fahrenheit scales.

59
1.5 Physical Properties (Read Section 1.4, pg 11)

• a. Length, Area and Volume
• Standard of length meter
• Area (length)2
• Standard m2
• Volume (length)3
• Standard m3
• liter most commonly used SI unit of volume for
• liquids
• 1 L 1 dm3
• 1 mL 1 cm3

60
b. Mass Weight

• Read, p16

61
c. Density

• The mass of a unit volume of substance
• d m / V wt / V -gt wt V x d V wt / d

62
Numeric Illustration

• Copper has a density of 8.96 g/cc. An Ingot of
  Copper with a mass of 57 kg is drawn into wire
  with a diameter of 9.50 mm. What length of wire
  can be produced? Note the volume of a cylinder
  is found using the relation V p x radius2 x
  length

63
Problem Solving Strategy

• Information provided
• Density of copper 8.96 g/cc
• Weight of ingot 57 kg 57000 g
• Diameter of wire 9.50 mm 0.950 cm
• Information Requested
• Length of the copper wire

64
Problem Solving Technique

• From Known to Next Unknown
• 1. Set up the expression of the final answer to
  the problem.
• 2. Use the known parameters in the expression to
  figure out the unknown parameters , one by one.
• Length V / (p x radius2)
• What parameter is unknown, how can it be found?
• See RQ2-10

65
RQ2-10

• Examine the relation Length V / (p x radius2).
  What parameter is unknown, how can it be found?
• a. r is unknown and can be found using the
  relation (r (V/(length x p))1/2
• b. V is unknown and can be found using the
  relation V (p x radius2) x length
• c. V is unknown and can be found using the
  relation V wt/d

66
Problem Solving (Continued)

• Unknown volume, to be determined next.
• Volume wt / d 57000 g / 8.96 (g/cc) ? cc
• Length ? E3 cc / (3.14 x (1/2 x 0.950)2) ? Cm
• Extra ex 65, pg 40