Exam #1 Flashcards
Hypothesis
An unverified explanation of a natural phenonmenon
Experiment
A procedure that tests the validity of a hypothesis
Observation
Information determined by noting and a natural phenomenon
Conclusion
An explanation of an observation that has been validated by repeated experiments that support a hypothesis.
Pure Substance
A type of matter that has a definite composition.
Element
A pure substance containing only one type of matter, which cannot be broken down by chemical methods.
Homogenous Mixture
In a homogeneous mixture, also called a solution, the composition is uniform throughout the sample. We cannot see the individual components, which appear as one state. Familiar examples of homogeneous mixtures are air, which contains oxygen and nitrogen gases, and seawater, a solution of salt and water.
Heterogenous Mixture
In a heterogeneous mixture, the components do not have a uniform composition throughout the sample. The components appear as two separate regions. For example, a mixture of oil and water is heterogeneous because the oil floats on the surface of the water. Other examples of heterogeneous mixtures are a cookie with raisins and orange juice with pulp.
Solid
A state of matter that has its own shape and volume.
Liquid
A state of matter that takes the shape of its container but has a definite volume.
Gas
A state of matter that does not have a definite shape or volume
Vaporization
The energy required to vaporize exactly 1 g of a substance at its boiling point. For water, 540 cal (2260 J) is needed to vaporize 1 g of liquid; 1 g of steam gives off 540 cal (2260 J) when it condenses at 100 °C.
Condesation
The change of state from a gas to a liquid.
Fusion
The energy required to melt exactly 1 g of a substance at its melting point. For water, 80. cal (334 J) is needed to melt 1 g of ice; 80. cal (334 J) is released when 1 g of water freezes at 0°C.
Sublimation
The change of state in which a solid is transformed directly to a gas without forming a liquid first.
Potential Energy
A type of energy related to position or composition of a substance.
Kinetic Energy
The energy of moving particles.
Calorie
Calories are referred to as either small (lowercase “c”) or large (uppercase “C”), with 1 large Calorie equalling 1,000 small calories. Scientifically,1 kcal or kilocalorie is equivalent to 1 large Calorie or 1,000 calories.
calorie
The amount of heat energy that raises the temperature of exactly 1 g of water by exactly 1 °C.
Joule
The SI unit of heat energy; 4.184 J = 1 cal.
How is heat transferred?
Heat is transferred through three primary mechanisms: conduction (direct contact between molecules), convection (movement of heated fluid), and radiation (electromagnetic waves) - all occurring when there is a temperature difference between objects, with heat always moving from a hotter to a colder area.
Specific Heat
A quantity of heat that changes the temperature of exactly 1 g of a substance by exactly 1 °C
Scientific Method
The process of making observations, proposing a hypothesis, and testing the hypothesis; after repeated experiments validate the hypothesis, it may become a theory.
Scientific Notation
A form of writing large and small numbers using a coefficient that is at least 1 but less than 10, followed by a power of 10.
Chemical
A substance that has the same composition and properties wherever it is found.
Chemistry
The study of the composition, structure, properties, and reactions of matter.
Theory
An explanation for an observation supported by additional experiments that confirm the hypothesis.
Submilation
The change of state in which a solid is transformed directly to a gas without forming a liquid first.
Heat Curve
A diagram that illustrates the temperature changes and changes of state of a substance as it is heated.
Heat
A state of matter that does not have a definite shape or volume.
Compound
A pure substance consisting of two or more elements, with a definite composition, that can be broken down into simpler substances only by chemical methods.
Mixture
The physical combination of two or more substances that are not chemically combined.
