Download Chemical Principles – by Steven Zumdahl (5 ) Chapter 1

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Chemical Principles – by Steven Zumdahl (5e)
Chapter 1 – Chemistry – The Science of Change
Chemistry is the study of the composition of matter , its
chemical and physical properties, the chemical and physical
changes that matter undergoes, and the energy changes that
accompany these processes.
Matter is anything that occupies space and has mass.
Energy is the capacity for doing work.
The Scientific Method – Figure 1.4.
Law of Nature: A Scientific Law is a statement based on
experiments that is believed to be true, and to which exceptions
are not known.
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Fundamental laws of Nature (for chemical reactions)
Law of conservation of matter: There is no detectible
increase or decrease in the quantity of matter during an
ordinary chemical change.
Law of conservation of energy: Energy cannot be created
or destroyed in an ordinary chemical reaction. It may
only be changed from one form to another.
Law of conservation of charge
More General:
Law of conservation of energy and mass: The total amount
of energy and mass in the universe is constant.
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States of Matter: We classify matter into several states because it
helps us classify information in a systematic way.
Solid State: Solids are rigid. They have definite shapes.
The dimensions of solids change slightly with temperature and
pressure.
Liquid State: Liquids flow and assume the shape of a container.
The volume of a liquid changes slightly with temperature and
pressure.
Gaseous State: Gases assume the shape of their container and fill
completely any container in which they are placed. Gases are
easily compressible and they expand indefinitely. The volume
of a gas changes with temperature and pressure.
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Solid State: Solids are rigid; they have a definite shape.
∆V
∆V
= smallest
= smallest
∆P
∆T
Liquid State: Flows and assumes the shape of the part of a
container that it occupies.
∆V
∆V
= small
= small
∆P
∆T
Gas State: Flows and fills a container.
∆V
= large
∆P
∆V
= large
∆T
∆V
∆ = “change in”.
Example: “
= large” would read:
∆P
“The change in volume of a gas divided by the
change in pressure on the gas equals a large quantity”.
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We can look at states of matter from a different perspective.
Solid State: Attractive forces between particles are so strong that
individual particles occupy fixed positions which are close
together.
Liquid State: Attractive forces between particles are strong
enough so that individual particles are close to each other, but
not fixed in position.
Gaseous State: Attractive forces between particles are very small,
and the particles are very far apart (compared to the particle
size).
Fsolid ≥ Fliquid ? Fgas
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H
O
H
H
O
H
Molecules are a group of two, or more, atoms
bonded together by forces strong enough to
maintain the existence of the molecule for a
reasonable time.
Properties are characteristics of matter. We divide
properties into two classes, chemical and physical properties.
Chemical Properties are properties that matter can exhibit only by
undergoing a change in composition (chemical change).
Physical Properties are properties that matter exhibits
without undergoing a change in composition.
Examples: melting ice: boiling water.
Substance is a material that cannot be separated by physical
means into two or more materials. (with different properties)
Elements are substances that cannot be decomposed by chemical
reactions. Elements (atoms) are the simplest forms of matter
(in chemistry). Each element is represented by a symbol.
You must memorize these symbols.
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Compounds are substances that are composed of two or more
elements in a definite (fixed) ratio by mass.
Atoms are the smallest particles of elements.
Mixture is a material that can be separated (by physical
means) into two or more substances.
A mixture can be
homogeneous (uniform to the observer), or
heterogeneous (not uniform to the observer).
Phase – a sample of matter that is uniform in chemical
composition and physical state.