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ChemistryVocabulary

Typicial CHemistry VOcab

QuestionAnswer
Analytical Chemistry The area of chemistry that focuses on the composition of matter
Applied Chemistry research that is direct toward a practical goal or application
Biochemistry the areas of chemistry that focuses on processes that take place in organisms
Biotechnology the field that applies science to the production of biological products or processes
Chemistry the study of the composition of matter and the changes that matter undergoes.
Experiment -a repeatable procedure that is used to test a hypothesis
Hypothesis a proposed explanation for an observation
Inorganic chemistry the study of substances that in general do not contain carbon
Macroscopic describes the world of objects that are large enough to see with the unaided eye
Matter anything that has mass and occupies space
Microscope describes the world of objects that can be seen only under magnification
Manipulated variable the variable that is changed during an experiment; also called independent
Observation information obtained through the senses; observation in science involving measurement
Organic chemistry the study of compounds containing carbon
Physical Chemistry the area of chemistry that deals with the mechanism, the rate and the energy transfer that occurs when matter undergoes change.
Pollutant a material found in air, water, or soil that is harmful to humans and other organisms
Pure Chemistry The pursuit of chemical knowledge for its own sake
Responding Variable the variable that is observed during an experiment; dependent variable
Scientific Law a concise statement that summarizes the results of many observations and experiments
Scientific Method a logical, systematic approach to the solutions of a scientific problem; steps in the scientific method include making observations, testing hypotheses and developing theories
Technology the means by which a society provides its members with those things needed and desired
Theory a well tested explanation for a broad set of observations
Chemical Change A change that produces matter with a different composition than the original.
Chemical property The ability of a substance to undergo a specific chemical change.
Chemical reaction A change in which one or more reactants change into one or more products; characterized by the breaking of bonds in reactants and the formation of bonds in products.
Chemical Symbol A one
Compound a substance that contains two or more elements chemically combined in a fixed proportion.
Distillation A process used to separate dissolved solids from a liquid, which is boiled to produce a vapor that is then condensed into a liquid.
Element the simplest form of matter that has a unique set of properties; an element cannot be broken down into simpler substances by chemical means.
Extensive property A property that depends on the amount of matter in a sample.
Filtration A process that separates a solid from the liquid in a heterogeneous mixture.
Gas A form of matter that takes the shape and volume of its container; a gas has no definite shape or volume.
Heterogeneous Mixture A mixture that is not uniform in composition; components are not evenly distributed throughout the mixture.
Homogeneous Mixture A mixture that is uniform in composition; Components are evenly distributed and not easily distinguished.
Intensive Property A property that depends on the type of matter in a sample, not the amount of matter.
Law of Conservation of Mass: In any physical change or chemical reaction mass is conserved; mass can be neither created or destroyed.
Liquid A form of matter that flows, has a fixed volume and a indefinite shape.
Mass A measure of the amount of matter that an object contains; the SI base unit of mass is the Kilogram.
Mixture A physical blend of two or more substances that are not chemically combined.
Phase any part of a sample with uniform composition and properties.
Physical Change A change during which some properties change but the composition of the material does not.
Physical Property A quality or condition of a substance that can be observed of measured without changing the substances composition.
Precipitate A solid that dorms and settles out of a liquid mixture.
Product A substance produced in a chemical reaction.
Reactant A substance present at the start of a reaction.
Solid A form of matter that has definite shape and volume.
Solution A homogeneous mixture; consists of solutes dissolved in a solvent.
Substance Matter that has uniform and definite composition; either an element or a compound; also called a pure substance.
Vapor Describes the gaseous state of a substance that is generally a liquid or a solid at room temperature.
Volume A measure of the space occupied by a sample of matter.
Absolute Zero The zero point on the Kelvin temperature scale, equivalent to -273.15°C.
Accepted Value A quantity used by general agreement of the scientific community.
Accuracy The closeness of a measurement to the true value of what is being measured.
Calorie(cal) The quantity of heat needed to raise the temperature of 1 g of pure water 1°C.
Celsius Scale The temperature scale on which freezing point of water is 0°C and the boiling point of water is 100°C.
Conversion Factor a ratio of equivalent measurements used to convert a quantity from one unit to another.
Density The ratio of mass of an object to its volume.
Dimensional Analysis A technique of problem solving that uses the units that read part of measurements to help solve the problem.
Energy The capacity for doing work or producing heat.
Error the difference between the accepted value and the experimental value.
Experimental Value a quantative value measured during an experiment.
Gram(g) a metric mass unit equal to the mass of 1 cm3 of water at 4°C.
International System of Units(SI) the revised version of the metric system adopted by international agreement in 1960
Joule(J) the SI unit of energy; 4.184 J=Calorie
Kelvin Scale the temperature scale in which freezing point is 273.15 K and the boiling point is 373.15K; 0K is absolute zero.
Kilogram(Kg) the mass of 1 L of water at 4°C; it is the base unit of mass in SI.
Liter(L) the volume of a cube measuring 10cm on each edge or 1000cm3; it is the common unprefixed unit of volume in the metric system.
Measurement a quantivtive description that includes both a number and a unit.
Meter(m) the base unit of length in SI
Percent error the percent that a measured value differs from the accepted value.
Precision describes the closeness or reproducibility of a set of measurements taken under the same conditions.
Scientific Notation an expression numbers in the form m X 10n where m is equal to or greater than one and less than 10, and n is an integer.
Significant Figures all the digits that can be known precisely in a measurements plus a last estimated digit.
Temperature a measure of the average kinetic energy of particles in matter; temperature determines the direction of heat transfer.
Weight a force that measure the pull of gravity one given mass.
Atom the smallest particle of an element that retains its identity in a chemical reaction
Atomic Mass the weighted average of the masses of the isotopes of an element
Atomic Mass Units(amu) a unit of mass equal to one
Atomic Number the number of protons in the nucleus of an atom of an element
Cathode Ray the electrode at which reduction occurs
Dalton's Atomic Theory the first theory to relate chemical changes to events at the atomic level
Electron a negatively charged subatomic particle
Group a vertical column of elements in the periodic table, the constituent elements of a group have similar chemical and physical properties
Isotopes atoms of the same element that have the same atomic number but different atomic masses due to a difference in number neutrons
Mass Number the total amount of protons and neutrons in the nuclear of an atom.
Neutron subatomic particle that has no charge and a mass of 1 amu; found in the nucleus of an atom
Nucleus the tiny dense central portion of an atom; composed of protons and neutrons
Period horizontal row of elements in the periodic table
Periodic Table an arrangement of elements in which the elements are separated into groups based on a set of repeating properties
Proton a positively charged subatomic particle found in the nucleus of an atom
Amplitude the height of a wave's crest
Atomic Emission Spectrum the pattern formed when light passes through a prism or diffraction grating to separate it into different frequencies of light it contains.
Atomic Orbital A mathematical expression describing the probability of finding an electron at various locations; usually represented by the region of space around the nucleus where there is a high probably of finding an electron
Aufbau Principle the rule that electrons occupy the orbital's of lowest energy first
Electromagnetic Radiation energy waves that travel in a vacuum at a speed of 2.998 X 108 m/s; includes radio, radar, micro, infrared, visible, ultraviolet, x
Electron Configurations the arrangement of electrons of an atom in its ground state into various orbital's around the nuclei of atoms
Energy Levels the specific energies an electron in an atom or other system can have
Frequency the number of wave cycles that pass a given point per unit of time; frequency and wavelength are inversely proportional to each other.
Ground State The lowest possible energy of an electron described by quantum mechanics.
Heisenberg Uncertainty Principle it is impossible to know exactly both the velocity and the position of a particle at the same time
Hertz the unit of frequency equal to one cycle per a second
Hund's Rule electrons occupy orbital's of the same energy in a way that makes the number of electrons with the same spin direction as large as possible
Pauli Exclusion Principle an atomic orbital may describe at most two electrons each with opposite spin directions
Photons a quantum of light; a discrete bundle of electromagnetic energy that interacts with matter similarly to particles.
Quantum the amount of energy needed to move an electron from one energy level to another
Quantum Mechanical Model the modern description, primarily mathematical of the behavior of electrons in atoms.
Spectrum wavelengths of visible light that are separated when a beam of light passes through a prism; range of wavelengths of EM radiation
Wavelength the distance between adjacent crests in a wave
Alkali Metals Any metal in group 1A of the periodic table
Alkaline Earth Metals any metal in group 2A of the periodic table
Anion Any atom or group of atoms with a negative charge
Atomic Radius one
Cation any atom or group of atoms with a positive charge
Electronegativity the ability of an atom to attract electrons
Halogens a nonmetal in group 7A of the periodic table
Inner Transition Metal an element in the lanthanide or actinide series; the highest occupied s sublevel and nearby f sublevel of its atoms generally contain electrons; also called inner transition elements
Ion an atom or group of atoms that has a positive or negative charge
Ionization Energy the energy required to remove an electron from an atom in its gaseous state
Metalloids an element that tends to have properties that are similar to those of metals and nonmetals
Metals one of a class of elements that are good conductors of heat and electric current; metals tend to be ductile, malleable and shiny
Noble Gases An element in group 8A of the periodic table; the s and p sublevels of the highest occupied energy level are filled
Nonmetals an element that tends to be a poor conductor of heat and electric current; nonmetals generally have properties opposite to those of metals
Periodic Law when the element are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties
Representative Elements an element in an "A" group in the periodic table. As a group of these elements display a wide range of chemical properties and physical properties. In their atoms, the s and p sublevels in the highest occupied energy level are partially full
Transition Metal one of the group B elements in which the highest occupied s sublevel and a nearby d sublevel generally contain electrons.
Alloys a mixture composed of two or more elements, at least one of which is metal
Chemical Formula An expression that indicates the number and type of atoms present in the smallest representative units of a substance
Coordination Number the number of ions of opposite chare that surround each ion in a crystal
Electron Dot Structure A notation that depicts valence electrons as dots around the atomic symbol of the element; the symbol represents the inner electrons and atomic nucleus; also called Lewis dot structure
Formula Unit the lowest whole-number ratio of ions in the ionic compound; in magnesium chloride the ratio of magnesium ions to chloride ions is 1
Halide Ion a negative ion formed when a halogen atom gains an electron
Ionic Bond the electrostatic attraction that binds oppositely charged ions together
Ionic Compounds a compound composed of positive and negative ions
Metallic Bonds the force of attraction that holds metal together; it consists of the attraction of free-floating valence electrons for positively charged metal ions
Octet Rule atoms react by gaining or losing electrons so as to acquire the stable electron structure of a Nobel gas, usually eight valence electrons
Valence Electron an electron in the highest occupied energy level of an atom.
Bond Dissociation Energy the energy required to break the bond between two covalently bonded atoms; this value is usually expressed in kJ per mol of a substance
Bonding Orbital a molecular orbital that can be occupied by two electrons of a covalent bond
Covalent Bond a bond formed by the sharing of electrons between atoms
Coordinate Covalent Bond a covalent bond in which one atom contributes both bonding electrons
Diatomic Molecule a molecule consisting of two atoms
Dipole a molecule that has two poles or regions with opposite charges
Dipole Interactions intermolecular forces resulting from the attraction of oppositely charged regions of polar molecules
Dispersion Forces attractions between molecules caused by the electron motion on one molecule affecting the electron motion on the other through electrical forces; these are the weakest interactions between molecules
Double Covalent Bond a bond in which two atoms share two pairs of electrons
Hybridization the mixing of several atomic orbital's to form the same total number of equivalent hybrid orbital's
Hydrogen Bonds attractive forces in which a hydrogen covalently bonded to a very electronegative atom is also weakly bonded to an unshared electron pair of another electronegative atom
Molecular Compound a compound that is composed of molecules
Molecular Formula chemical formula of a molecular compound that shows the kinds and numbers of atoms present in a molecule of a compound
Molecular Orbital an orbital that applies to the entire molecule
Molecule a neutral group of atoms joined together by covalent bonds
Network Solids a solid in which all of the atoms are covalently bonded to each other
Non polar Covalent bond
Pi Bond a covalent bond in which the bonding electrons are most likely to be found in sausage
Polar Bond a covalent bond between atoms in which the electrons are shared unequally
Polar Covalent Bond aka polar bond
Polar Molecule a molecule in which one side of the molecule is slightly negative and the opposite side is slightly positive
Polyatomic Ion a tightly bond group of atoms that behaves as a unit and has a positive or negative charge
Resonance Structure one of the two or more equally valid electron dot structures of a molecule or polyatomic ion
Sigma Bond a bond formed when two atomic orbital combine to form a molecular orbital that is symmetrical around the axis connection the two atomic nuclei
Single Covalent Bond a bond formed when two atoms share a pair of electrons
Structural Formula a chemical formula that shows the arrangement of atoms in a molecule or polyatomic ion; each dash between a pair of atoms indicates a pair of shared electrons
Tetrahedral Angle a bond angle of 109.5 that results when a central atom forms four bonds directed toward the center of a regular tetrahedron
Triple Covalent Bond a covalent bond in which three pairs of electrons are shared by two atoms
Unshared Pair a pair of valence electrons that is no shared between atoms aka lone pair
Van der Waals Forces the two weakest intermolecular attractions
VSEPR Theory valence
Acid a compound that produces hydrogen ions in solution
Base a compound that produces hydroxide ions in solution
Binary Compound a compound composed of two elements
Law of Definite Proportions in samples of any chemical compound the masses of the elements are always in the same proportion
Law of Multiple Proportions whenever two elements form more than one compound the different masses of one element combine with the same mass of the other elements to form simple whole umber ratios
Monatomic Ion a single atom with a positive and negative charge resulting from the loss or gain of one or more valence electrons
Polyatomic Ion a tightly bound group of atoms that behaves as a unit and has a positive or negative charge
Avogadro's hypothesis equal volumes of gases at the same temperature and pressure contains equal numbers of particles
Avogadro's Number the number of representatives particles contained in one mole of a substance; equal to 6.02 X 10 23particles
Empirical Formula a formula with the lowest whole number ratio of elements in a compound
Molar Mass a term used to refer to the mass of a mole of any substance
Molar Volume the column occupied by one mole of gas at STP (22.4L)
Mole(mol) the amount of substance that contains 6.02 X 10 23 representative particles of that substance.
Percent Composition the percent by mass of each element in a compound
Representative Particle the smallest unit into which a substance ca be broken down without a change in composition usually atoms molecules or ions.
Standard Temperature and Pressure(STP) the conditions under which the volume of a gas is usually measured; 0 degrees Celsius and 101.3kPa or 1 atmosphere(atm)
Activity Series a list of elements in order of decreasing activity; the activity series of halogens is Fl, Cl, Br, I
Balanced Equation a chemical equation in which mass is conserved; each side of the equation has the same number of atoms of each element
Catalyst A substance that speeds up the rate of reaction by lowering the activation energy barrier; the catalysts is not used up in the reaction.
Chemical Equation an expression representing a chemical reaction; the formulas of the reactants (L) are connected by an arrow with the formulas for the products(r.)
Coefficients a small whole number that appears in front of a formula to a balanced equation
Combination Reaction or synthesis; is a chemical change in which two or more substances react to form a single new substance
Combustion Reaction a chemical change in which an element or a compound reacts with oxygen, often producing energy in the form of heat and light.
Complete Ionic Equation an equation that shows dissolved ionic compounds as dissociated free ions
Decomposition Reaction a chemical change in which a single compound is broken down into two or more simpler products
Double Replacement Reaction a chemical change that involves an exchange of positive ions between compounds
Net Ionic Equation an equation for a reaction in solution showing only those particles that are directly involved in the chemical change
Single Replacement Reaction a chemical change in which one element replaces a second element in a compound; also called displacement reaction
Skeleton Equation a chemical equation that does not indicate the relative amounts of reactants and products
Spectator Ion an ion that is not directly involved in a chemical reaction; an ion that does not change oxidation number or composition during reaction.
Actual Yield the amount of product that forms when a reaction is carried out in the laboratory
Excess Reagent a reagent present in a quantity that is more than sufficient to react with a limiting; any reactant that remains after the limiting reagent is used up in a chemical reaction
Limiting Reagent any reagent that is used up first in a chemical reaction; it determines the amount of product that can be formed in the reaction
Mole Ratio a conversion factor derived from the coefficients of a balanced chemical equation interpreted in terms of moles
Percent Yield the ratio of the actual yield to the theoretical yield for a chemical reaction expressed as a percentage; a measure of the efficiency of a reaction
Stoichiometry the portion of chemistry dealing with numerical relationships in chemical reaction; the calculation of quantities of substances involved in chemical equations.
Allotrope one of two or more different molecular forms of an element in the same physical state; graphite and diamond
Amorphous Solid describes a solid that lacks an ordered internal structure; denotes a random arrangement of atoms
Atmospheric Pressure the pressure exerted by atoms and molecules in the atmosphere surrounding earth, resulting from collisions of these particles with objects.
Barometer an instrument used to measure atmospheric pressure
Boiling Point the temperature at which vapor pressure of a liquid is just equal to the external pressure on the liquid (BP)
Crystal a solid in which the atoms, ion or molecules are arranged in an orderly, repeating three dimensional pattern called a crystal lattice
Evaporation vaporization that occurs at the surface of a liquid that is not boiling
Gas Pressure results from the force exerted by a gas per unit surface area of an object; due to collisions of gas particles with the object
Glass transparent fusion product of inorganic materials that have cooled to a rigid state without crystallizing
Kinetic Energy the energy an object has because of its motion
Kinetic Theory a theory explaining the states of matter, based on the concept that all matter consists of tiny particles that are in constant motion
Melting Point the temperature at which a substance changes from a solid to a liquid; the melting point of water is 0 degrees Celsius (MP)
Normal Boiling Point the boiling point of a liquid at a pressure of 101.3kPa or 1 atm
Pascal the SI unit of pressure
Phase Diagram a graph showing the conditions at which a substance exists as a solid, liquid or vapor
Standard Atmosphere(atm) a unit of pressure; it is the pressure required to support 760 mm of mercury in a mercury barometer at 25 degrees Celsius
Sublimation the process in which a solid changes to a gas or vapor without passing through the liquid state
Triple Point the point on a phase diagram that represents the only set of conditions at which all three phases exist in equilibrium with one another
Unit Cell the smallest group of particles within a crystal that retains the geometric shape of the crystal
Vacuum a space where no particles of matter exist
Vaporization the conversion of liquid to a gas or vapor
Vapor Pressure a measure of the force exerted by a gas above a liquid in a sealed container; a dynamic equilibrium exists between the vapor and the liquid
Boyle's Law for a given mass of gas at constant temperature, the volume of the gas varies inversely with pressure
Charles's Law the volume of a fixed mass of gas is directly proportional to its Kelvin temperature if the pressure is kept constant
Combined Gas Law the law that describes the relationship among the pressure, temperature, and volume of an enclosed gas
Compressibility a measure of how much the volume of matter decreases under pressure
Dalton's Law Of Partial Pressures at constant volume and temperature the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the component gases
Diffusion the tendency of molecules to move toward areas of lower concentration until the concentration is uniform throughout.
Effusion the process that occurs when a gas escapes through a tiny hole in its container
Gay-Lussac's Law the pressure of a gas is directly proportional to the Kelvin temperature if the volume is constant
Graham's Law of Effusion the rate of effusion of a gas inversely proportional to the square root of its molar mass; this relationship is also true for diffusion of gases
Ideal Gas Constant the constant in the ideal gas law with the symbol R that has the value 8.31 (L*kPa)/(K*mol)
Ideal Gas Law the relationship PV =nRT which describes the behavior of an ideal gas
Partial Pressure the contribution each gas in a mixture of gases makes to the total pressure
Aqueous Solution water that contains dissolved substances
Browian Motion the chaotic movement of colloidal particles, caused by collision with particles of the solvent in which they are dispersed
Colloid a mixture whose particles are intermediate in size between those of a suspension and a solute solution
Electrolyte a compound that conducts an electric current when it is in an aqueous solution or in the molten state; all ionic compound are electrolytes but most covalent compounds are not.
Emulsion the colloidal dispersion of one liquid in another
Hydrate a compound that has a specific number of water molecules bound to each formula unit
Nonelectrolyte a compound that does not conduct an electric current in aqueous solution or in the molten state
Solute dissolved particles in a solution
Solvation a process that occurs when an ionic solute dissolves; in a solution, solvent molecules surround the positive and negative ions
Solvent the dissolving medium in a solution
Strong Electrolyte a solution in which a large portion of the solute exists as ions
Surfactant any substance that that interferes with the hydrogen bonding between water molecules and thereby reduces surface tension; soap and detergents are surfactants
Suspension a mixture from which some of the particles settle out slowly upon standing
Surface Tension an inward force that tends to minimize the surface area of a liquid; it causes the surface to behave as if it were a thin skin
Tyndall Effect scattering of light particles in a colloid or suspension, which causes a beam of light to become visible
Weak Electrolyte a solution that conducts electricity poorly because only a fraction of the solute exists as ions
Boiling Point Elevation the difference in temperature between the boiling point of a solution and the boiling point of a pure solvent
Concentrated Solution a solution containing a large amount of solute
Concentration a measurement of the amount of a solute that is dissolved in a given quantity of solvent; usually expressed in mol/L
Colligative Property a property of a solution that depends solely upon the number of solute particles, and not upon their identities; boiling point elevation, freezing point depression and vapor pressure lowering are colligative
Dilute Solution a solution that contains a small amount of solute
Freezing Point Depression the difference I temperature between the freezing point of a solution and the freezing point of the pure solvent
Henry's Law at a given temperature the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid
Immiscible describes liquids that are insoluble in one another; oil and water
Miscible describes liquids that dissolve one another in all proportions
Molal Freezing Point depression Constant Kf, the change in freezing point for a 1 Molal solution of a nonvolatile molecular solute
Molal Boiling Point Elevation Constant Kb, the change in boiling point for a 1 Molal solution of a nonvolatile molecular solute
Molality (m) the concentration of solute in a solution expressed as the number of moles of solute dissolved in 1 kg or 1000 g of solvent
Molarity (M) the concentration of a solute in a solution expressed as the number of moles of solute dissolved in 1L of solution
Mole Fraction the ratio of the moles of solute in solution to the total number of moles of both solvent and solute
Saturated Solution a solution containing the maximum amount of solute for a given amount of solvent at a constant temperature and pressure; an equilibrium exists between un-dissolved ions and dissolved ions in solution
Solubility the amount of a substance that dissolves in a given quantity of solvent at specified conditions of temperature and pressure to produce a saturated solution
Supersaturated Solution a solution that contains more solute than it can theoretically hold at a given temperature; excess solute precipitates if a seed crystal is added
Unsaturated Solution a solution that contains less solute than a saturated solution at a given temperature and pressure
Calorimeter an insulated devise used to measure the absorption or release of heat in chemical or physical processes
Calorimetry the precise measurement of heat flow out of a system for chemical or physical processes
Chemical Potential Energy energy stored in chemical bonds
Endothermic Process a process that absorbs heat from the surrounding
Enthalpy (H) the heat content of a system at constant pressure
Exothermic Process a process that releases heat to its surroundings
Heat (q) energy that transfers from one object to another because of a temperature difference between the objects
Heat Capacity the amount of heat needed to increase the temperature of an object exactly 1°C
Heat of Combustion the heat of reaction for the complete burning of one mole of a substance
Heat of Reaction the enthalpy change for a chemical equation exactly as it is written
Hess's Law of Heat Summation if you add two or more Thermochemical equations to give a final equation then you also add the heats of reaction to give the final heat of reaction
Law of Conservation of Energy in ay physical change or chemical reaction, mass is conserved; mass can be neither created or destroyed
Molar Heat of Condensation ( ∆Hcond) the amount of heat released by one mole of a vapor as it condenses to a liquid at a constant temperature
Molar Heat of Fusion (∆Hfus) the amount of heat absorbed by one mole of a solid substance as it melts to a liquid at a constant temperature
Molar Heat of Solidification (∆Hsolid) the amount of heat lost by one mole of a liquid as it solidifies at a constant temperature
Molar Heat of Solution (∆Hsoln) the enthalpy change caused by the dissolution of one mole of a substance
Molar Heat of Vaporization (∆Hvap) the amount of heat absorbed by one mole of a liquid as it vaporizes at a constant temperature
Specific Heat the amount of heat needed to increases the temperature of 1 g of a substance 1°C; also called specific heat capacity
Standard Heat of Formation (∆Hf0) the change in enthalpy that accompanies the formation of one mole of a compound from its elements with all substances in their standard states at 25°C
Surroundings everything in the universe outside of the system
System a part of the universe on which you focus your attention
Thermochemical Equation a chemical equation that includes the enthalpy change
Thermochemistry the study of energy changes that occur during chemical reactions and changes in state
Activated Complex an unstable arrangement of atoms that exists momentarily at the peak of the activation-energy barrier; an intermediate or transitional structure formed during the course of a reaction
Activation Energy the minimum energy colliding particles must have in order to react
Chemical Equilibrium a state of balance in which the rates of the forward and reverse reactions are equal; no net charge in the amount of reactants and products occurs in the chemical system
Collision Theory atoms, ions, and molecules can react to form products when they collide, provided that the particles have enough kinetic energy
Common Ion an ion that is common to both salts in a solution; in a solution of silver nitrate and silver chloride Ag+ is the common ion
Common Ion Effect a decrease in the solubility of an ionic compound caused by the addition of a common ion
Elementary Reaction a reaction in which reactants are converted to products in a single step
Entropy (s) a measure of the disorder of a system; systems tend to go from a state of order(low) to a state of maximum disorder(high)
Equilibrium Constant (Keq) the ratio of product concentrations to react concentrations at equilibrium, with each concentration raised to a power equal to the umber of moles of that substance in the balanced chemical equation
Equilibrium Position the relative concentrations of reactants and products of a reaction that has reached equilibrium; indicates whether the reactants or products are favored in the reversible reaction
First-Order Reaction a reaction in which the reaction rate is proportional to the concentration of only one reactant
Free Energy the energy available to do work
Gibbs Free Energy Change ∆G the maximum amount of energy that can be coupled to another process to do useful work
Inhibitor a substance that interferes with the action of a catalysts
Intermediate a product of one of the steps in a reaction mechanism; it becomes a reactant in the next step
Law of Disorder it is natural tendency of systems to move in the direction of maximum chaos or disorder
Le Chatliers Principle when stress is applied to a system dynamic equilibrium, the system changes in a way that relieves the stress
Nonspontaneous Reaction a reaction that does not favor the formation of products at the specifies conditions
Rate describes the speed of change over an interval of time
Rate Law an expression relating the rate of reaction to the concentration of reactants
Reaction Mechanism a series of elementary reactions that take place during the course of a complex reaction
Reversible Reaction a reaction in which the conversion of reactants into products and the conversion of products into reactants occur simultaneously
Solubility Product Constant Ksp the equilibrium constant applied to the solubility of electrolytes; it is equal to the product of the concentration of the ions each raised to the power equal to the coefficient of the ion in the dissociation equation
Specific Rate Constant a proportionality constant relation the concentration of reactions to the rate of reaction
Spontaneous Reaction a reaction that favors the formation of products at the specified conditions; spontaneity depends on enthalpy and entropy changes
Transition State a term sometime used to refer to the activated complex
Acid Dissociation Constant (Ka) The ratio of the concentration of the dissociated form of an acid to the undissocitated form; stronger acids have larger Ka Values than weaker acids
Acidic Solution any solution in which the hydrogen-ion concentration is greater than the hydroxide-ion concentration
Alkaline Solution a basic solution
Amphoteric a substance that can act as both an acid and a base
Base Dissociation Constant (Kb) the ratio of the concentration of the conjugate acid times the concentration of the hydroxide ion to the concentration of conjugate base
Basic Solution any solution in which the hydroxide-ion concentration is greater than the hydrogen-ion concentration
Buffers a solution in which the pH remains relatively constant when small amounts of acid or base are added; a buffer can be either a solution of a weak acid and the salt of a weak acid or a solution of a weak base with the salt of a weak base
Buffer Capacity a measure of the amount of acid or base that may be added to a buffer solution before a significant change in pH occurs
Conjugate Acid the particle formed when a base gains a hydrogen-ion; NH4+ is the conjugate acid of the base NH3
Conjugate Acid-Base Pair two substances that are related by the loss or gain of a single hydrogen ion; ammonia (NH3) and the ammonia ion (NH4+) are a conjugate acid-base pair
Conjugate Base the particle that remains when an acid has donated a hydrogen ion; OH- is the conjugate base of the acid water
Diprotic Acid any acid that contains two ionizable protons (hydrogen ions); sulfuric acid (H2SO4) is a Diprotic acid
End Point the point in a titration at which the indicator changes color
Equivalent Point the point of titration where the number of moles of hydrogen ions equals the number of moles of hydroxide ions
Hydronium Ion(H3O+) the positive ion formed when a water molecule gains a hydrogen ion
Ion-Product Constant for Water(Kw) the product of the concentration of hydrogen ions and hydroxide ions in water; it is 1*10-14 at 25 degrees Celsius
Lewis Acid any substance that can accept a pair of electrons to form a covalent bond
Lewis Base any substance that can donate a pair of electrons to form a covalent bond
Monoprotic Acid any acid that contains one ionizable proton (hydrogen ion); nitric acid is a Monoprotic acid
Neutral Solution an aqueous solution in which the concentration of hydrogen and hydroxide ions are equal; it has a pH pf 7.0
Neutralization Reaction a reaction in which an acid and a base react in a aqueous solution to produce a salt and water
pH a number use to denote the hydrogen-ion concentration or acidity of a solution; it is the negative logarithm of the hydrogen-ion concentration of a solution
Salt Hydrolysis a process in which the cations or anions of a dissociated salt accept hydrogen ions from water or donate hydrogen ions to water
Self-Ionization a term describing the reaction in which two water molecules react to produce ions
Standard Solution a solution of known concentration used in carrying our a titration
Strong Acid an acid that is completely (or almost completely) ionized in aqueous solution
Strong Base a base that completely dissociates into metal ions and hydroxide ions in aqueous solution
Titration process used to determine the concentration of a solution (often an acid or base) in which a solution of known concentration (the standard) is added to a measured amount of the solution of unknown concentration until an indicator signals the end point
Tripotic Acid any acid that contains three ionizable protons (hydrogen ions)
Weak Acid an acid that is only slightly ionized in aqueous solution
Weak Base a base that reacts with water to form the hydroxide ion and the conjugate acid of the base
Created by: Trackster