General Chemistry, 5 th ed. Whitten, Davis & Peck Chapter 1 Definitions Left click your mouse to continue.

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ACCURACY How closely a measured value agrees with the correct value

CALORIE Exactly joules.

CHEMICAL CHANGE A change in which one or more new substances are formed. One or more substances are used up (at least partially). Energy is absorbed or released.

CHEMICAL PROPERTY Properties exhibited by matter as it undergoes changes in composition.

COMPOUND A substance composed of two or more elements in fixed proportions. Compounds can be decomposed into their constituent elements.

DENSITY Mass per unit volume; D = m/V

ELEMENT A substance that cannot be decomposed into simpler substances by chemical means.

ENDOTHERMIC Describes processes that absorb heat energy. Ex: The absorption of heat is required to turn water into steam, therefore the process is endothermic

ENERGY The capacity to do work or transfer heat.

EXOTHERMIC Describes processes that release heat energy. Ex: Freezing water to make ice requires the release of heat, therefore the process is exothermic.

EXTENSIVE PROPERTY A property that depends upon the amount of material in a sample.

HEAT A form of energy that flows between two samples, always flows spontaneously from a hotter body to a colder body

HEAT CAPACITY The amount of heat required to raise the temperature of a body (of whatever mass) one degree Celsius.

HETEROGENEOUS MIXTURE A mixture that has uniform composition and properties throughout. Ex: A mixture of salt and charcoal; foggy air; vegetable soup

HOMOGENEOUS MIXTURE A mixture that has a uniform composition and properties throughout; also called a solution. Ex: Saltwater; air (free of particulate matter or mists); alloys

INTENSIVE PROPERTY A property that is independent of the amount of material in a sample. All chemical properties are intensive properties. Ex: Color, Melting Point

JOULE A unit of energy in the SI system. One joule is 1 kg*m 2 /s 2, which is also calorie

KINETIC ENERGY Energy that matter possess by virtue of its motion.

LAW OF CONSERVATION OF ENERGY Energy cannot be created or destroyed in a chemical reaction or in a physical change; it may be changed from one form to another.

LAW OF CONSERVATION OF MATTER There is no detectable change in the quantity of matter during a chemical reaction or during a physical change.

LAW OF CONSERVATION OF MATTER AND ENERGY The combined amount of matter and energy available in the universe is fixed.

LAW OF DEFINITE PROPORTIONS Different samples of any pure compound contain the same elements in the same proportions by mass; also known as the Law of Constant Composition

MASS A measure of the amount of matter in an object. Mass is usually measured in grams or kilograms.

MATTER Anything that has mass and occupies space.

MIXTURE A sample of matter composed of variable amounts of two or more substances, each of which retains its identity and properties.

PHYSICAL CHANGE A change in which a substance changes from one physical state to another, but no substances with different compositions are formed.

POTENTIAL ENERGY Energy that matter possess by virtue of its position, condition, or composition.

PHYSICAL PROPERTIES Can be observed in the absence of any change in composition. Ex: color, density, hardness, melting point, boiling point, and electrical and thermal conductivities

PRECISION How closely repeated measurements of the same quantity agree with each other.

PROPERTIES Characteristics that describe samples of matter. Chemical properties are exhibited as matter undergoes chemical 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 measurements- 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. Dimensionless number (I.e., no units).

SPEFIC HEAT The amount of heat required to raise the temperature 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 A letter or group of letters that represent (identifies) an element.

TEMPERATURE A measure of the intensity of heat

UNIT FACTOR A factor in which the numerator and denominator are expressed in different units but represent the same or equivalent 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.

Equation for converting F to C F = 1.8(C ) + 32

Equation for converting C to F C = (F – 32)/1.8

Equation for converting C to K K = C + 273

Equation for converting K to C C = K - 273

Equation for Specific Heat Specific Heat = (amount of HEAT in Joules) (MASS in Grams)(T 2 –T 1 in Celsius )