What is Chemistry

1
What is Chemistry?

• Chemistry is a study of matter and the changes it
  undergoes
• Coal- Burning of coal
• Air- Breathing
• Eggs- Boiling eggs

2
Why study chemistry?

• Chemistry is the scientific study of matter, and
  matter is everywherethink of a field in science-
  biology, physics, geology, ecology all require
  the knowledge of matter

3
Ecological footprint

• A tool that measures how much land and water area
  a human population requires to produce the
  resources it consumes and to absorb its wastes
  under prevailing technology.

4
What is matter?

• Matter is anything that has mass and occupies
  space.
• Is bread a matter?
• Is air a matter?
• Mass is-a measurement of the amount of matter in
  an object.
• Mass is independent of the location of an object.
• An object on the earth has the same mass as the
  same object on the moon.

5
What are the types of properties?

• Physical properties can be observed or measured
  without attempting to change the composition of
  the matter being observed.
• Examples ?
• Chemical properties can be observed or measured
  only by attempting to change the composition of
  the matter being observed.
• Examples ?

6
Chemistry- Study of Change

• Physical changes of matter
• Physical changes take place without a change in
  composition.
• Examples freezing, melting or evaporation of a
  substance such as water.

7
Chemistry- Study of Change

• Chemical changes of matter
• Chemical changes are always accompanied by a
  change in composition.
• Examples burning of paper, the fizzing of a
  mixture of vinegar and baking soda.

8
Classification of Matter

• Mixtures can be further classified
• Homogeneous Mixture- Uniform appearance and same
  properties throughout
• Heterogeneous Mixture- Properties and appearance
  non-uniform throughout
• Exercise 1.22

9
Chemistry- Study of Atoms and Molecules

• A molecule is the smallest particle of a pure
  substance that is capable of a stable independent
  existence.
• An atom is the smallest unit of an element that
  can exist as a stable, independent entity. Atoms
  make up molecules.
• Diatomic molecules contain two atoms.
• Triatomic molecules contain three atoms.
• Polyatomic molecules contain more than three
  atoms.
• Homoatomic molecules contain atoms of the same
  kind.
• The atoms contained in heteroatomic molecules are
  of two or more kinds.

10
Chemistry- Study of Atoms and Molecules

• Oxygen gas-
• Homoatomic
• Diatomic

Carbon monoxide- Heteroatomic Diatomic
Carbon dioxide- Heteroatomic Triatomic
11
Classification of Matter

• Examples-
• Elements
• Compounds
• Exercise 1.18

12
Stuff

• Raw materials?
• Other ingredients?
• Living/Non-living or synthetic?
• Processes?
• Energy sources?
• Quantities? Measurements?

13
Measurements and Units

• Why do we need measurements?
• Measurements consist of-
• a number
• a unit or label (feet, pounds or gallons)
• Examples ??
• The metric system is a decimal system in which
  larger and smaller units are related by factors
  of 10.

14
Common prefixes of metric system
15
SI Units

• 7 Base quantities and units (SI-International
  System of Units)

Number of derived units of measurements. Multiplic
ation/Division of one or more base units
16
Length related commonly used Derived Units

• Area- (Length) (Length)
• Pg 41
• Volume- (Length) (Length) (Length)
• Pg 50

Temperature Scale
Fahrenheit ? 32 F freezing, 212F Water
boiling Pg 10, 37 Kelvin (Also called the
absolute scale) Celsius ? 0C freezing, 100C
Water boiling Rankine (Not common)
17
Temperature Scale
18
Conversion of Temperature scales

• Converting Fahrenheit to Celsius
• C 5/9 (F 32)
• Converting Celsius to Fahrenheit
• F 9/5 (C ) 32
• Converting Kelvin to Celsius
• C K 273
• Converting Celsius to Kelvin
• K C 273
• Example 1.7
• Exercise 1.43
• Pg 78

19
Can you quantify/measure these?

• How many miles do you drive daily?
• How many miles you ride (bus/bike) daily?
• How much water do you consume-
• Shower
• Drinking
• Cooking
• Flush
• How many gallons of water do you consume as per
  your water (utilities) bill?
• What is your vehicles gas mileage? Gas cost
  weekly/monthly?
• How many times you fly in a year? How many miles
  do you fly in a year?
• How much money you spend on coffee
  weekly/monthly?
• Your daily consumption of electricity as per the
  electricity (utilities) bill?

20
The Process of Lying or the Art of Numbers!
April 3rd 2007
April 5th 2007
http//dilbert.com/
21
Numbers and more numbers

• 0.000000000005
• Scientific Notation
• Product of two parts in the form M x 10n
• - M is a number between 1 and 10 (but not equal
  to 10)
• - n is a positive or negative whole number
• 0.000000000005 becomes
• M written with the decimal in the standard
  position
• The standard position for the decimal is to the
  right of the first nonzero digit in the number M
• 0.005 becomes 5.0 10-3

5.0 10-12
22
Numbers and more numbers

• Significance of the exponent n
• A positive n value indicates the number of places
  to the right of the standard position that the
  original decimal position is located.
• A negative n value indicates the number of
  places to the left of the standard position that
  the original decimal position is located.
• Learning check 1.10
• Operations with scientific notations
• Example 1.11

23
Numbers and more numbers

• Measurements are limited by the device in use.
• Significant Figures
• Significant figures are the numbers in a
  measurement that represent the certainty of the
  measurement, plus one number representing an
  estimate.
• 1.5 cm ? Significant figures 2
• 0.015 m ? Significant figures 2
• 1.50 cm ? Significant figures 3
• Leading zeros are never significant figures.
• Buried and trailing zeros are always significant
  figures.
• Learning check 1.13

24
Numbers and more numbers

• Rules for operations
• Multiplication or division- same number of
  significant figures as the quantity with the
  fewest number of significant figures used in the
  calculation.
• Addition or subtraction- same number of places
  to the right of the decimal as the quantity in
  the calculation with the fewest number of places
  to the right of the decimal.
• Rounding Rules
• First of the nonsignificant figures to be
  dropped is 5 or greater ? last remaining
  significant figure is increased by one.
• First of the nonsignificant figures to be
  dropped i less than 5 ? last remaining
  significant figure is left unchanged.

25
Dimensional Analysis (Factor-Unit method)

• Step 1 Write down the known or given
  quantity.Include both the numerical value and
  units of the quantity.
• Step 2 Leave some working space and set the
  known quantity equal to the units of the unknown
  quantity.
• Step 3 Multiply the known quantity by one or
  more factors such that the units of the factor
  cancel the units of the known quantity and
  generate the units of the unknown quantity.
• Step 4 After you generate the desired units of
  the unknown quantity, do the necessary arithmetic
  to produce the final numerical answer.

26
Dimensional Analysis (Factor-Unit method)

• Step 1 Write down the known or given
  quantity.Include both the numerical value and
  units of the quantity.
• 2.54 m (Numerical Value 2.54 Units meters)
• Step 2 Leave some working space and set the
  known quantity equal to the units of the unknown
  quantity.
• 2.54 m --- cm

27
Dimensional Analysis (Factor-Unit method)

• Step 3 Multiply the known quantity by one or
  more factors such that the units of the factor
  cancel the units of the known quantity and
  generate the units of the unknown quantity.
• 2.54 m --- cm
• Step 4 After you generate the desired units of
  the unknown quantity, do the necessary arithmetic
  to produce the final numerical answer.
• 254 cm

28
Percentage

• Pg 34, Pg 68
• percentage means per one hundred
• Percentage calculation-
• Pg 49

29
Density

• Density is the ratio of the mass of a sample of
  matter divided by the volume of the same sample.
• or
• Density calculation involves knowledge of
• Mass and b) Volume
• Example 1.20
• Pg 38

30
Density

• A 20.00 mL sample of liquid is put into an empty
  beaker that had a mass of 31.447 g. The beaker
  and contained liquid were weighed and had a mass
  of 55.891 g. Calculate the density of the liquid
  in g/mL.
• Mass of the liquid Mass of the beaker with
  contained liquid Mass of the empty beaker