Exercises 41Physical property See Properties.
Potential energy Energy that matter possesses by virtue of its
position, condition, or composition.
Precision How closely repeated measurements of the same
quantity agree with one another.
Properties Characteristics that describe samples of matter.
Chemical properties are exhibited as matter undergoes chemi-
cal changes. Physical properties are exhibited by matter with
no changes in chemical composition.
Scientific (natural) law A general statement based on the
observed behavior of matter, to which no exceptions are known.
Significant figures Digits that indicate the precision of mea-
surements — digits of a measured number that have uncertainty
only in the last digit.
Specific gravity The ratio of the density of a substance to the
density of water at the same temperature.
Specific heat The amount of heat required to raise the temper-
ature of one gram of a substance one degree Celsius.
Substance Any kind of matter all specimens of which have the
same chemical composition and physical properties.
Symbol (of an element) A letter or group of letters that repre-
sents (identifies) an element.
Temperature A measure of the intensity of heat, that is, the
hotness or coldness of a sample or object.
Unit factor A factor in which the numerator and denominator
are expressed in different units but represent the same or equiv-
alent amounts. Multiplying by a unit factor is the same as
multiplying by one.
Weight A measure of the gravitational attraction of the earth for
a body.Exercises
Asterisks are used to denote some of the more challenging ex-
ercises.Matter and Energy
*61.Define the following terms, and illustrate each with a spe-
cific example: (a) matter; (b) energy; (c) mass; (d) exother-
mic process; (e) intensive property.
*62.Define the following terms, and illustrate each with a spe-
cific example: (a) weight; (b) potential energy; (c) kinetic
energy; (d) endothermic process; (e) extensive property.
*63.State the following laws, and illustrate each.
(a) the Law of Conservation of Matter
(b) the Law of Conservation of Energy
(c) the Law of Conservation of Matter and Energy
*64.List the three states of matter and some characteristics of
each. How are they alike? different?
*65.An incandescent light bulb functions because of the flow
of electric current. Does the incandescent light bulb con-
vert all of the electrical energy to light? Observe a func-
tioning incandescent light bulb, and explain what occurs
with reference to the Law of Conservation of Energy.
*66.All electrical motors are less than 100% efficient in con-
verting electrical energy into useable work. How can their
efficiency be less than 100% and the Law of Conservation
of Energy still be valid?States of Matter
*67.What is a homogeneous mixture? Which of the following
are pure substances? Which of the following are homoge-
neous mixtures? Explain your answers. (a) sugar dissolved
in water; (b) tea and ice; (c) french onion soup; (d) mud;
(e) gasoline; (f ) carbon dioxide; (g) a chocolate-chip cookie.*68.Define the following terms clearly and concisely. Give two
illustrations of each: (a) substance; (b) mixture; (c) element;
(d) compound.
*69.Classify each of the following as an element, a compound,
or a mixture. Justify your classification: (a) a soft drink;
(b) water; (c) air; (d) chicken noodle soup; (e) table salt;
(f ) popcorn; (g) aluminum foil.
*10.Classify each of the following as an element, a compound,
or a mixture. Justify your classification: (a) coffee; (b) sil-
ver; (c) calcium carbonate; (d) ink from a ballpoint pen;
(e) toothpaste.
*11.Sand, candle wax, and table sugar are placed in a beaker
and stirred. (a) Is the resulting combination a mixture?
If so, what kind of mixture? (b) Design an experiment
in which the sand, candle wax, and table sugar can be
separated.
*12.A $10 gold piece minted in the early part of the 1900s ap-
peared to have a dirty area. The dirty appearance could not
be removed by careful cleaning. Close examination of the
coin revealed that the “dirty” area was really pure copper.
Is the mixture of gold and copper in this coin a heteroge-
neous or homogeneous mixture?Chemical and Physical Properties
*13.Distinguish between the following pairs of terms and give
two specific examples of each: (a) chemical properties and
physical properties; (b) intensive properties and extensive
properties; (c) chemical changes and physical changes;
(d) mass and weight.
*14.Which of the following are chemical properties, and which
are physical properties? (a) Baking powder gives off bubbles
of carbon dioxide when added to water. (b) A particular