MODULE # 1

Subject CHM012 Chemistry for Engineers

Chapter/Unit 1
Lesson Title Matter and Energy
Timeframe Week 1
Lesson Objectives 1) Classify properties of matter as intrinsic or extrinsic, physical or chemical
properties and give examples for each
2) Differentiate the changes in matter as physical, chemical or nuclear changes and
give examples for each.
3) Describe properties of solids, liquids and gas.
4) Compare elements, compounds and mixtures
5) Distinguish the forms of energy and cite energy transformations
Overview/Introduction Chemistry is the study of matter, its properties, and the changes that matter
undergoes. As you progress in this course, you will come to see how chemical
principles operate in all aspects of our lives, from everyday activities like food
preparation to more complex processes such as those that operate in the environment.
We will also learn how the properties of substances can be tailored for specific
applications by controlling their composition and structure. This first chapter
provides an overview of what chemistry is about and what chemists usually do.
Activity Exercises/Assignment
Assessment Problem Set
References Brown, T.L., LeMay Jr., H.E., Bursten, B.E., Murphy, C.J., Woodward, P.M., “Chemistry –
The Central Science”, (14th edition), Prentice-Hall International, Inc. (Chapter 1)

CHEMISTRY: DEFINITION AND SCOPE

The Study of Chemistry

Chemistry:

→ the study of the properties and behavior of matter. Matter is the physical material of the universe; it is
anything that has mass and occupies space.
→ can be applied to all aspects of life (e.g., development of pharmaceuticals, leaf color change in fall etc.) and
is at the heart of many changes we see in the world around us.

Why Study Chemistry?

We study chemistry because:

 It has a considerable impact on society (health care, food, clothing, conservation of natural resources,
environmental issues etc.).
 It is part of your curriculum! Chemistry serves biology, engineering, agriculture, geology, physics etc.
Chemistry is the central science.

Major Areas of Chemistry

• Organic chemistry is the study of matter that is composed principally of carbon and hydrogen.

• Inorganic chemistry is the study of matter that consists of all the elements other than carbon and hydrogen
and their combinations.
• Analytical chemistry involves the analysis of matter to determine its composition and the quantity of each
kind of matter that is present.

• Physical chemistry is the study of the physical principles that underly the structure of matter, energy
changes, and chemical transformations.

• Biochemistry is the study of life in the molecular level and the processes associated with life, such as
reproduction, growth and respiration.

MATTER: CLASSIFICATION AND PHYSICAL STATES

Matter

Matter is the physical material of the universe; it is anything that has mass and occupies space. All matter is
comprised of combinations of only about 100 substances called elements. One of our major goals of Chemistry
will be to relate the properties of matter to its composition, that is, to the particular elements it contains.

Matter is typically characterized by (1) its physical state (gas, liquid, or solid) and (2) its composition (whether
it is an element, a compound, or a mixture).

States of Matter
• Solids, liquids and gases are the three forms of matter called the states of matter.

Properties described on the macroscopic level:

Gas: No fixed volume or shape, conforms to shape of container, compressible.

Liquid: Volume independent of container, no fixed shape, incompressible.

Solid: Volume and shape independent of container, rigid, incompressible.

Properties described on the molecular level:

Gas: Molecules far apart, move at high speeds,

collide often.

Liquid: Molecules closer than gas, move rapidly but

can slide over each other.

Solid: Molecules packed closely in definite

arrangements.

Exercise 1
1. Match the following characteristics to one or more of the three states of matter:
a. has no shape of its own
b. definite shape
c. occupies the total volume of a container
d. partially takes on the shape of a container
e. does not take on the shape of a container
f. readily compressible
g. slightly compressible
h. essentially noncompressible

Composition of Matter
Pure substances:

 matter with distinct properties and with fixed composition that does not vary from sample to sample. Water
and table salt (sodium chloride) are examples of pure substances. All pure substances are either elements or
compounds.
o Elements (cannot be decomposed into simpler substances, i.e. only one kind of atom).
o Compounds (consist of two or more elements). For example, Water (H2O) is a compound
composed of two elements, Hydrogen (H) and Oxygen (O)

Mixtures:

– combination of two or more pure substances; each substance retains its own identity.
Elements
 Currently, there are 118 known elements.
 cannot be broken down by chemical reaction
 consist of only one type of atom
 vary in abundance.
 each is given a unique name.
 organized in periodic table.
 each is given a one- or two-letter symbol derived from its name.

Compounds
 Compounds are combinations of elements (Example: The compound H2O is a combination of elements H
and O)
 The opposite of compound formation is decomposition. (Decomposing pure water into its constituent
elements shows that it contains 11% hydrogen and 89% oxygen by mass, regardless of its source)
 can be broken down by chemical reaction
 Compounds have different properties than their component elements (e.g., water is liquid, hydrogen and
oxygen are both gases at the same temperature and pressure).

 Law of Constant (Definite) Proportions (Proust): A compound always consists of the same combination
of elements (e.g., water is always 11% H and 89% O).

Exercise 2
Which of the following figures represents (a) a pure element, (b) a mixture of two elements, (c) a pure
compound, (d) a mixture of an element and a compound? (More than one picture might fit each description.)

Mixtures
 A mixture is a combination of two or more pure substances.
o Each substance in a mixture retains its own chemical identity and property
o In contrast to a pure substance, the composition of a mixture can vary.
 A mixture can be:
o Heterogeneous (do not have uniform composition, properties and appearance throughout, e.g.,
sand, rocks, wood).
o Homogeneous (uniform throughout, e.g., air: mixture of nitrogen, oxygen and smaller
amounts of gases). Homogenous mixtures are solutions. (e.g salt, sugar and other substances
dissolve in water)

Exercise 3
(a) Classify each of the following as a pure substance, a solution, or a heterogeneous mixture: a gold coin, a cup
of coffee, a wood plank. (b) What ambiguities are there in answering part (a) from the descriptions given?

Solution:
a. A gold coin is probably a solid solution. Pure gold (element 79) is too soft and too valuable to be used for
coinage so other metals are usually added; A cup of coffee is a solution (if there no suspended solids like
coffee grounds) or an heterogenous mixture if there are grounds. If cream or sugar is added, the
homogeneity of the mixture depends on how thoroughly the components are mixed; A wood plank is a
heterogenous mixture of various cellulose components. The different domains of in the mixture are visible
as wood grain or knots.
b. The ambiguity in each of these examples is that the name of the substance does not provide a complete
description of the material. We rely on mental images, and these vary from person to person.

PROPERTIES OF MATTER
Each substance has a unique set of physical and chemical properties:

 Physical properties: can be observed without changing the identity and composition of the substance (e.g.,
color, density, odor, melting point, boiling point, hardness).
 Chemical properties: Describe how substances react or change to form different substances (e.g.,
flammability: the ability of a substance to burn in the presence of oxygen).
Properties may be categorized as intensive or extensive:

 Intensive properties: Do not depend on amount of substance present (e.g., temperature, melting point etc.).
 Extensive properties: Depend on quantity of substance present (e.g., mass, volume etc.).

Intensive properties give an idea of the composition of a substance whereas extensive properties given an
indication of the quantity of substance present.

Physical and Chemical Changes

The changes substances undergo are either physical or chemical.
• Physical change: substance changes physical appearance without altering its identity

e.g., changes of state, changing shape, changing physical state, dissolving, boiling water, melting ice,
hammering gold into foil

• Chemical changes (or chemical reactions): substances transform into chemically different substances (i.e.
identity changes)

e.g., decomposition of water, explosion of nitrogen triiodide, oxidation of matter (burning or rusting), release
of gas bubbles (fizzing), formation of insoluble solid (precipitation), release of heat or light, hydrogen
burns in air (forming water)

Exercise 4

1. Milk turns sour. This is a ________________

 Chemical Change
 Physical Change
 Chemical Property
 Physical Property
 None of the above
2. HCl being a strong acid is a __________, Wood sawed in two is ___________
 Chemical Change, Physical Change
 Physical Change, Chemical Change
 Chemical Property, Physical Change
 Physical Property, Chemical Change
 None of the above
3. Copper Sulfate is dissolved in water
 Chemical Change
 Physical Change
 Chemical Property
 Physical Property
 None of the above
4. Aluminum Phosphate has a density of 2.566 g/cm3
 Chemical Change
 Physical Change
 Chemical Property
 Physical Property
 None of the above
Separation of Mixtures
We can separate a mixture into its components by taking advantage of differences in their properties
Key: Separation techniques exploit differences in properties of the components.

 Filtration: Remove solid from liquid.

 Distillation: Boil off one or more components of the mixture; a process that depends on the different
abilities of substances to form gases
 Chromatography: Exploit solubility of components; uses differing abilities of substances to adhere to the
surfaces of solids

Exercise 5

1. Suggest a method of separating each of the following mixtures into two components: (a) sugar and
sand, (b) oil and vinegar [Hint: the two liquids have different solubilities and densities].
2. Three beakers contain clear, colorless liquids. One beaker contains pure water, another contains salt
water, and another contains sugar water. How can you tell which beaker is which? (No tasting
allowed!) [Hint: boiling point of pure water is 100 °C; sugar has a lower melting point than salt]
Solution:

a. Sugar and Sand: The two solids had different water solubilities. Add water to dissolve the sugar, then filter
the mixture. Collect the sand on the filter paper and the sugar water in the flask. Evaporate water from the
flask to recover solid sugar.; Oil and Vinegar: Take advantage of the different solubilities and densities of
the two liquids. Allow the mixture to settle so that there are two distinct layers. Vinegar (a water solution) is
denser and on the bottom while the oil (the organic layer) is on the top. Carefully pour off the most of the
top layer and after the layers reform, use a dropper to remove remaining oil.

THE NATURE OF ENERGY

All objects in the universe are made of matter, but matter alone is not enough to describe the behavior of the
world around us. To understand chemistry, we must also understand energy and the changes in energy that
accompany chemical processes.

Energy is defined as the capacity to do work or transfer heat.

 Work is the energy transferred when a force exerted on an object causes a displacement of that object.
We define work, w, as the product of the force exerted on the object, F, and the distance, d, that it
moves:
w=Fxd
 Heat is the energy used to cause the temperature of an object to increase.

Kinetic Energy and Potential Energy

To understand energy we need to grasp its two fundamental forms, kinetic energy and potential energy.
 Kinetic Energy: The energy of motion. The magnitude of kinetic energy, Ek, of an object depends on
its mass, m, and velocity, v:

Thus, the kinetic energy of an object increases as its velocity or speed increases. In chemistry we are
interested in the kinetic energy of atoms and molecules.
 Potential Energy: All other forms of energy—the energy stored in a stretched spring, in a weight held
above your head, or in a chemical bond—are classified as potential energy. Potential energy is, in
essence, the “stored” energy.
One of our goals in chemistry is to relate the energy changes seen in the macroscopic world to the kinetic or
potential energy of substances at the molecular level. Many substances, fuels for example, release energy when
they react. The chemical energy of a fuel is due to the potential energy stored in the arrangements of its atoms.
As we will learn in later lessons, chemical energy is released when bonds between atoms are formed, and
consumed when bonds between atoms are broken.

ASSIGNMENT

Exercise 1, Exercise 2, Exercise 4, Exercise 5 (#2)

Deadline: September 25, 2020