AP Chemistry TEST #3 – Flashcards
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| Vapor |
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| Gaseous state of any substance that normally exists as a liquid or solid |
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| Pressure |
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| A measure of the force exerted on a unit area. In chemistry, pressure is often expressed in units of atmospheres (atm) or torr: 760 torr = 1 atm; in SI units pressure is expressed in pascals (Pa) |
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| pascal (Pa) |
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| The SI unit of pressure: 1 Pa = 1 N/m2 |
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| Bar |
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| A unit of pressure equal to 105 Pa |
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| Standard Atmospheric Pressure |
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| Defined as 760 torr or, in SI units, 101.325 kPa |
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| Atmosphere (atm) |
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| A unit of pressure equal to 760 torr; 1 atm = 101.325 kPaa |
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| Torr |
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| A unit of pressure (1 torr = 1 mm Hg) |
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| Boyle's Law |
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| A law stating that at constant temperature, the product of the volume and pressure of a given amount of gas is a constant. |
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| Charles's Law |
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| A law stating that at constant pressure, the volume of a given quantity of gas is proportional to absolute temperature. |
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| Avogadro's Hypothesis |
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| A statement that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules |
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| Avogadro's Law |
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| A statement that the volume of a gas maintained at constant temperature and pressure is directly proportional to the number of moles of the gas. |
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| Ideal Gas Equation |
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| An equation of state for gases that embodies Boyle's law, Charles's Law, and Avogadro's hypothesis in the form of PV=nRT. |
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| Ideal Gas |
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| A hypothetical gas whose pressure, volume, and temperature behavior is completely described by the ideal-gas equation. |
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| Gas Constant (R) |
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| The constant of proportionality in the ideal-gas equation. |
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| Standard Temperture and Pressure (STP) |
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| Defined as 0;C and 1 atm pressure; frequently used as reference conditions for a gas |
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| Partial Pressures |
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| The pressure exerted by a particular gas in a mixture. |
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| Dalton's Law of Partial Pressures |
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| A law stating that the total pressure of a mixture of gases is the sum of the pressures that each gas would exert if it were present alone. |
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| Mole Fraction |
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| The ratio of the number of moles of one component of a mixture to the total moles of all components; abbreviated X, with a subscript to identify the component |
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| Kinetic Molecular Theory |
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| A set of assumptions about the nature of gases. These assumptions, when translated into mathematical form, yield the ideal-gas equation. |
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| Root-mean-Square (rms) Speed |
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| The square root of the average of the squared speeds of the gas molecules in a gas sample. |
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| Effusion |
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| The escape of a gas through an orifice or hole. |
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| Graham's Law |
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| A law stating that the rate of effusion of a gas is inversely proportional to the square root of its molecular weight. |
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| Diffusion |
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| The spreading of one substance through;a space occupied by one or more other substances. |
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| Mean Free Path |
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| The average distance traveled by a gas molecule between collisions. |
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| Phase Changes |
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The conversion of a substance from one state of matter to another. The phase changes we consider are melting and freezing (solid ; liquid), sublimation and deposition (solid ; gas), and vaporization and condensation (liquid ;gas). |
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| Heat of Fusion |
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| The enthalpy change, ;H, for melting a solid |
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| Heat of Vaporization |
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| The enthalpy change, ;H, for vaporization of a liquid. |
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| Heat of Sublimation |
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| The enthalpy change, ;H, for vaporization of a solid. |
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| Critical Temperature |
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| The highest temperature at which it is possible to convert the gaseous form of a substance to a liquid. The criticl temperature increases with an increase in the magnitude of intermolecular forces. |
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| Critical Pressure |
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| The pressure at which a gas at its critical temperature is converted to a liquid state. |
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| Vapor Pressure |
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| The pressure exerted by a vapor in equilibrium with its liquid or solid phase. |
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| Phase Diagram |
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| A graphic representation of the equilibria among the solid, liquid, and gaseous phases of a substance as a function of temperature and pressure. |
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| Normal Melting Point |
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| The melting point at 1 atm of pressure. |
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| Triple Point |
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| The temperature at which solid, liquid, and gas phases coexist in equilibrium. |
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| Crystalline Solid (crystal) |
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| A solid whose internal arrangement of atoms, molecules, or ions shows a regular repetition in any direction through the solid. |
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| Amorphous Solid |
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| A solid whose molecular arrangement lacks a regular, long-range pattern. |
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| Unit Cell |
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| The smallest portion of a crystal that reproduces the structure of the entire crystal when repeated in different directions in space. |
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| Crystal Lattice |
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| An imaginary network of points on which the repeating unit of the structure of a solid (the contents of the unit cell) may be imagined to be laid down so that the structure of the crystal is obtained. Each point represents an identical environment in the crystal. |
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| Primitive Cubic Cell (or simple cubic) |
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| A cubic unit cell in which the lattice points are at the corners only. |
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| Body-Centered Cubic Cell |
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| A cubic unit cell in which the lattice points occur at the corners and at the center |
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| Face-Centered Cubic Cell |
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| A cubic unit cell that has lattice points at each corner as well as at the center of each face |
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| Hexagonal Close Packing |
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| A close-packing arrangement in which the atoms of the third layer of a solid lie directly over those in the first layer. |
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| Cubic Close Packing |
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| ;A close packing arrangement in which the atoms of the third layer of a solid are not directly over those in the first layer |
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| Coordination Number |
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| The number of adjacent atoms to which an atom is directly bonded. In a complex the coordination number of the metal ion is the number of donor atoms to which it is bonded. |
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| Molecular Solids |
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| Solids that are composed of molecules. |
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| Covalent Network Solids |
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| Solids in which the units that make up the three-dimensional network are joined by covalent bonds. |
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| Ionic Solids |
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| Solids that are composed of ions. |
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| Metallic Solids |
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| Solids that are composed of metal atoms. |
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| Solvation |
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| The clustering of solvent molecules around a solute particle. |
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| Hydration |
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| Solvation when the solvent is water. |
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| Entropy |
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| A thermodynamic function associated with the number of different;equivalent energy states or spatial arrangements in which a system may be found. It is a thermodynamic state function, which means that once we specify the conditions for a system-that is, the temperature, pressure, and so on-the entropy is defined. |
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| Saturated Solution |
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| A solution in which undissolved;solute and dissolved solute are in equilibrium. |
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| Solubility |
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| The amount of a substance that dissolves in a given quantity of solvent at a given temperature to form a saturated solution. |
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| Unsaturated Solution |
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| Solutions containing less solute than a saturated solution. |
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| Supersaturated Solutions |
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| Solutions containing more solute than an equivlent saturated solution. |
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| Miscible |
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| Liquids that mix in all proportions. |
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| Immiscible Liquids |
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| Liquids that do not dissolve in one another to a significant extent. |
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| Mass Percentage |
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| The number of grams of solute in each 100 g of solution. |
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Parts Per Million (ppm) ; |
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| The concentration of a solution in grams of solute per 106; (million) grams of solution; equals milligrams of solute per liter of solution for aqueous solutions. |
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| Molality |
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| The concentration of a solution expressed as moles of solute per kilogram of solvent; abbreviated m. |
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| Colligative Properties |
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| Those properties of a solvent (vapor-pressure lowering, freezing-point lowering, boiling-point elevation, osmotic pressure) that depend on the total concentration of solute particles present. |
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| Raoult's Law |
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| A law stating that the partial pressure of a solvent over a solution, PA, is given by the vapor pressure of the pure solvent, P(0/A), times the mole fraction of a solvent in the solution, XA : PA = XAP(0/A) |
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| Ideal Solution |
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| A solution that obeys Raoult's law |
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Molal Boiling-Point-Elevation Constant (Kb) ; |
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| A constant characteristic of a particular solvent that gives the increase in boiling point as a function of solution molality: ;Tb = Kbm |
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| Molal Freezing-Point-Depression Constant (Kf) |
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| A constant characteristic of a particular solvent that gives the decrease in freezing point as a function of solution molality: ;Tf = Kfm |
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| Osmosis |
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| The net movement of solvent through a semipermeable membrane toward the solution with greater solute concentration |
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| Osmotic Pressure, ; |
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| The pressure that must be applied to a solution to stop osmosis from pure solvent into the solution. |
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| Colloids (Colloidal Dispersions) |
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| Mixtures containing particles larger than normal solutes but small enough to remain suspended in the dispersing medium. |
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| Tyndall Effect |
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| The scattering of a beam of visible light by the particles in a colloidal dispersion. |
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| Hydrophilic |
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| Water-attracting. The term is often used to describe a type of colloid. |
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| Hydrophobic |
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| Water-repelling. The term is often used to describe a type of colloid. |
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| Paramagnetism |
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| A property that a substance possesses if it contains one or more unpaired electrons. A paramagnetic substnace is drawn into a magnetic field |
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| Diamagentism |
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| A type of magnetism that causes a substance with no unpaired electrons to be weakly repelled from a magnetic field. |
