Need help on an exam on Chemistry
njm.500
Chapter1-part1.pdf
1/8/2018
1
N'vida E. Houndonougbo
Chapter 1-part 1
Learning objectives
• Define chemistry and describe its role in our society (1.1)
• Describe the early practice of chemistry.
• Identify the steps in the scientific method.
• Describe the modern practice of chemistry.
N'vida E. Houndonougbo
Chapter 1
Learning objectives
• Describe the importance of green chemistry and sustainable
chemistry (1.1)
• Differentiate mass and weight; physical and chemical
change; and physical and chemical properties. (1.5)
• Classify matter according to state and as mixture, substance,
compound, and/or element. (1.6)
• Describe the significance of the laws of definite proportions.
(2.2)
• Define alloys and their importance in our society
• Write chemical formulas
• Distinguish atoms from molecules. (2.6)
1/8/2018
2
N'vida E. Houndonougbo
Chapter 1 (con’t)
Learning objectives
• Write numbers using scientific (exponential)
notations
• Assign proper units of measurement to
observations and manipulate units in conversions.
(1.7)
• Calculate the density, mass, or volume of an object
given the other two quantities. (1.8)
• Explain how the temperature scales are related.
(1.9)
• Distinguish between heat and temperature. (1.9)
N'vida E. Houndonougbo
Chapter 1
Chapter 1: Suggested Assignment
• Page 35: problem 29
• Page 36: Problems 30 to 42; 45, 47,50
• Page 37: Problems 53-59; 65-68
• Page 92: Problem 39
• Page 159: Problems 7 to 10
• A-4 Appendix: Scientific notations
• A-14 Appendix: Calculation involving temperature
•
1/8/2018
3
N'vida E. Houndonougbo
Chapter 1
Outline
I. Chemistry and its role in our society
II. Classification of matter
III. Physical changes
IV. Chemical changes
V. Scientific (exponential) notations
VI. Units of measurement
VII. Density
VIII. Heat and Temperature
N'vida E. Houndonougbo
Chemistry and its role in society
Food Soap
Chemistry has an important role in our society
The chemical structure of sodium stearate, a typical soap.
beta-Carotene is responsible for the
orange color of carrots and many other
fruits and vegetables.
1/8/2018
4
N'vida E. Houndonougbo
Chemistry and its role in society
Toothpaste
Active Ingredients: Sodium Fluoride 0.24%
(0.15% w/v fluoride ion)
Hand Sanitizer
N'vida E. Houndonougbo
Chemistry and its role in society
Clothing
1/8/2018
5
N'vida E. Houndonougbo
Chemistry and its role in society
Medicine or prescription drugs
N'vida E. Houndonougbo
Chemistry and its role in society
Energy
Some of the main components of gasoline: isooctane, butane, 3-ethyltoluene, and the octane enhancer MTBE.
1/8/2018
6
N'vida E. Houndonougbo
Chemistry and its role in society
Knowledge of chemistry is important to :
understand the material world around us
Example in class
Turn raw materials into useful products.
Example in class
N'vida E. Houndonougbo
Chemistry: Science that studies of matter and its transformation.
Science: way of acquiring knowledge about nature through observation and experimentation.
What is Chemistry?
1/8/2018
7
N'vida E. Houndonougbo
The Scientific Method
The scientific method involves several steps:
Step 1: Scientists perform a planned experiment, make observations, record, analyze data and frame scientific law .
Step 2: Scientists propose a tentative hypothesis to explain the experimental observations.
Step 3: Scientists conduct additional experiments to test the hypothesis. If the evidence supports the initial proposal, the hypothesis may become a scientific theory.
N'vida E. Houndonougbo
The Scientific Method
Scientific laws: summarize large amounts of
scientific data and provide descriptions of natural
phenomena.
Example in class
Many scientific laws can be stated mathematically.
Example in class
1/8/2018
8
N'vida E. Houndonougbo
The Scientific Method
Scientific hypotheses: testable explanations
of observed data.
A scientific theory is a set of tested
hypotheses that explain natural phenomena.
N'vida E. Houndonougbo
Modern Chemistry
Modern chemistry is divided into several branches:
Organic chemistry is the study of substances containing carbon.
Inorganic chemistry is the study of all other substances that don’t contain carbon.
Biochemistry is the study of substances derived from plants and animals.
1/8/2018
9
N'vida E. Houndonougbo
Modern Chemistry
Green chemistry: the design of chemical processes that reduce waste and hazardous substances.
Example in class:
• Sustainable chemistry is designed to meet the needs of the present generation without compromising the needs of future generations.
Example in class:
N'vida E. Houndonougbo
Chemistry: A central science.
Chemistry is a central science.
1/8/2018
10
N'vida E. Houndonougbo
Evolution of Chemistry
Ancient Greeks attempted to formulate theories
about natures but they did not test their theories by
experimentation.
The experimental root of chemistry started with
alchemists who tried unsuccessfully to turn various
metals into gold.
Alchemists perfected some chemical techniques
Such as distillation and extraction
N'vida E. Houndonougbo
Evolution of Chemistry
Chemistry developed out of natural philosophy but
had its true beginnings when people began to rely
on experiments.
1/8/2018
11
N'vida E. Houndonougbo
Chemistry is the science that studies of matter (qualitatively and quantitavely) and its transformation
Matter:
• Anything that has mass and occupies space
• Example in class
Chemistry a natural science
N'vida E. Houndonougbo
Mass and Weight
Mass and weight are often used interchangeably but
they differ.
Mass is the measure of the amount of matter in an
object.
Weight is the measure of the gravitational force on the
matter in an object.
Example: Discussed in class
1/8/2018
12
N'vida E. Houndonougbo
Mass and Weight
The weight of anything depends on where it is in the
universe and especially on the gravitational force
acting on it.
Example in class
N'vida E. Houndonougbo
Physical Properties
Properties of a substance that can be observed or measured without changing the substance.
Examples are:
• color.
• mass.
• weight.
1/8/2018
13
N'vida E. Houndonougbo
Chemical Properties
Chemical property describes its chemical reactions with other substances.
The chemical properties can only be observed when a substance is changed into another substance.
N'vida E. Houndonougbo
Chemical Properties
Examples: Page 14
1/8/2018
14
N'vida E. Houndonougbo
Physical Changes
physical changes:
changes in which the chemical identity of the
substance is not altered.
Example of physical changes
• Changes of form
• Changes of size
• Change of appearance
• Changes of state
N'vida E. Houndonougbo
Changes in Physical States
Change of state
•Most substances can exist as either a solid, a liquid, or a gas.
Example in class
•A substance can change physical states as the temperature changes.
Example of Change of state
Melting: Solid Liquid Freezing: Liquid Solid
Vaporization: Liquid gas Condensation: Gas Liquid
Sublimation: Solid gas Deposition: Gas solid
1/8/2018
15
N'vida E. Houndonougbo
Chemical changes
In the course of a chemical change, the reacting
substances are converted to new substances.
Chemical change: change in which the identity of pure substances is altered as a result of the rearrangement of atoms.
.
N'vida E. Houndonougbo
Some evidence of chemical changes
There following observations indicate that a chemical
reaction is taking place.
A gas is produced.
Gas may be observed in many ways in a reaction from
light fizzing to heavy bubbling.
Example in class
1/8/2018
16
N'vida E. Houndonougbo
Some evidence of chemical changes
An insoluble solid is produced in a solution
Example in class:
The insoluble solid formed is called a precipitate.
N'vida E. Houndonougbo
A permanent color change is observed.
• Many chemical reactions involve a permanent color change.
• A change in color indicates that a new substance has been formed.
Some evidence of chemical changes
1/8/2018
17
N'vida E. Houndonougbo
Some evidence of chemical changes
Heat and light being given off.
