CHEM 151: EXAM 1
66 Cards in this Set
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Homogenous
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A mixture that the substances are evenly spread throughout.
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Heterogenous
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mixtures that have different properties in different parts of the system
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Intensive Properties
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Properties that do not depend upon the amount of matter present such as melting point, density, and conductivity.
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Extensive properties
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properties that are dependent on the amount of substance such as mass and volume.
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Physical change
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A phase transition
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Phase diagram
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graphical representation of phase change and stability
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Triple point
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A point where three different phases can occur at the same temperature and pressure.
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Supercritical fluid
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Exists as both fluid and gas.
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critical point
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liquid and vapor are indistinguishable
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Vapor
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gaseous state of any substance that normally exists as a liquid or solid
high rate of temperature, pressure, and evaporation
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Filtration
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Solid substances are separated from liquids
-Uses a barrier only the liquid can pass through
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Crystallization
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A solution of a solute is cooled below saturation temperature, causing solid crystals of solute to form.
-commonly used in process such as extraction of common salt.
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Distillation
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Technique used to separate substances in a liquid mixture taking advantage of boiling point.
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hydrocarbons
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organic molecules containing only carbon and hydrogen atoms
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Models
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Simplified representations
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Particulate Model of Matter
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Used to explain and predict the physical properties of many materials.
Assumption 1: Any macroscopic sample of a substance is composed of an extremely large number of very small identical particles.
Assumption 2: Particles of matter are constantly moving in random directions through emp…
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Ideal gas and Ideal gas law
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hypothetical gas whose pressure, volume and temperature relationships are described completely by the ideal-gas equation
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Kinetic energy
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energy that a body possesses by virtue of being in motion
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potential energy
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stored energy that could do work but is not doing so.
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Latent heat
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The energy released or absorbed during a phase transition due to changes in potential energy.
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atomic model of substances
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Proposed that the particles that compose the substance in our surroundings have internal structure.
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atoms
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composed of protons, neutrons, and electrons
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Chemical Bonds
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when atoms combine by sharing/transferring valence electrons
-covalent, ionic, hydrogen
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molecules
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groups of two or more atoms held together by chemical bonds
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Elementary substances
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are composed of identical particles made of free or bonded atoms of the same type
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Chemical Compounds
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a combination of two or more elements, chemically combined
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Ionic compounds
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tend to be solids with high melting points that conduct electricity when dissolved in water or in the liquid state.
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Molecular compounds
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are variable in their state of matter and in general are not food electrical conductors in any phase.
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Metals
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are usually solids at room temperature and conduct heat and electricity remarkably well.
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Non metals
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are gases under the same conditions as metals and are poor conductors of heat and electricity.
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Metalloids
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They share properties of both nonmetals and metals
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Mass Spectrometry
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A technique for measuring the mass, and therefore the molecular weight of ions.
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Empirical formula.
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The formula that represents the simplest ratio of the atoms of each element present in a compound.
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Chromatography
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-Substances can be separated from each other according to how soluble they are in a particular solvent: the more water-soluble the substance, the farther it will creep (diffuse) along the chromatography paper in a polar solvent. Nonpolar substances will move farther in a nonpolar solvent.…
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Organobromines
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are organic compounds made up of molecules in which carbon atoms are bonded to bromine atoms.
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Avogadro's number
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6.02x1023
Number of particles, molecules, atoms in a mole
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Standard conditions
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-1atm
273.15 K (0C)
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concentration
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how much of a substance we have per unit volume of the mixture
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Carbon
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Is black
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Hydrogen
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Is grey
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Oxygen
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is red
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nitrogen
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is blue
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Potential energy...
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Is related to temperature.
More heat=less potential energy
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Configurations are related to...
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pressure
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Lower potential energy=
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more favorable
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more pressure
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less configurations
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father apart=
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more potential energy
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closer together=
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more kinetic energy, less potential energy, more favorable
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Why do water puddles eventually disappear?
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Faster particles at the surface of the liquid are constantly escaping and being blown away.
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Why does the coiling temperature of water decrease with decreasing external pressure?
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Water particles in the liquid phase have to push the surrounding gas (air) to escape; the higher the external pressure the higher the kinetic energy needed for particles to push the surrounding gas.
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Phase stability
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for any given substance, different phases are stable at different values of temperature and pressure.
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Volatile
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higher vapor pressure at the same time
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Pressure and temperature are...
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Directly proportional meaning that as one increases so does the other.
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A solid...
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Has low potential energy and low configurations
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Gas...
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Has high potential energy and high configurations
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Molar mass
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is finding the atomic mass and then multiplying each mass by the number of atoms and then adding each element together.
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Empirical formula
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is a formula giving the proportions of the elements present in a compound but not the actual numbers or arrangements of atoms.
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atomic mass
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the bottom number on the periodic element in the table.
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Mass and speed
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more mass the less speed.. Also related to kinetic energy.
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Kinetic Energy =
1/2 x Mass x Speed2
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...
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Relationship between Kinetic energy and potential energy
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If potential energy decreases then the kinetic energy increases.
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Ion
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charged particle
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Atomic number means
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the number of protons
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isotope
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one of several atomic forms of an element, each with the same number of protons, thus differing in atomic mass
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Mass spectrometry
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an instrumental method for identifying the chemical constitution of a substance by means of the separation of gaseous ions according to their differing mass and charge —called also mass spectroscopy.
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sublimation
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when the surface particles of a solid gain enough energy that they form a gas
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