chemisty 2
Terms
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- hydration
- solvation when the solvent is water
- saturated
- a solution that is in equilibrium with undissolved solute
- solubility
- the amount of solute needed to form a sturated solution in a fiven quantity of solvent
- unsaturated
- contains less solute than a saturated solution
- supersaturated
- contains a greater amount of solute than needed to form a saturated solution
- miscible
- pairs of liquids such as acetone and water that mix in all proportions
- immiscible
- pairs of liquids that don not dissolve significantly in one another
- Henry's law
- the concentration of gas in a solution is proportinal to the pressure of gas over the solution.
- mass percentage
- =(mass of component in soln)/(total mass of soln) * 100
- parts per million
- = (mass of component in soln)/(total mass of soln) * 10^6
- molality
- = (moles solute)/(kg of solvent)
- Raoult's law
- the partial pressure exerted by solvent vapor above a solution equals the product of the mole fraction of the solvent in the solution times the vapor pressure of the pure solvent
- molal boiling-point-elevation constant
- a constant characteristic of a particular solvent that gives the change in boiling point as a functino of solution molality
- molal freezing-point-depression constant
- a constant characteristic of a particular solvent that gives the change in freezing point as a function of solution molality
- osmosis
- net movement of solvent molecules from the less concentrated solution into the more concentrated one. (net movement is always toward the solution with the higher solute concentration)
- osmotic pressure
- the pressure required to prevent osmosis
- colloidal dispersions / colloids
- intermediate types of dispersions or suspensions
- hydrophilic
- water loving
- hydrophobic
- water fearing
- chemical kinetics
- the area of chemistry concerned with the speeds at which reactions occur
- instantaneous rate
- the rate at a particular time as opposed to the average rate over an interval of time
- first-order reaction
- one whose rate depends on teh concentration of a single reactant raised to the first power
- half-life
- the time required for the concentration of a reactant to drop to one half of its intitial value
- second-order reaction
- one whose rate depends on the reactant concentration raised to the second power or on the concentrations of two different reactants, each raised to the first power
- collision model
- explains the factors influencing reaction rates in terms of the frequency of collisions, the number of collisions with energies exceeding the activation energy, and the probability that the coliisions occur with suitable orienttations.
- activation energy
- the minimum energy required to initiate a chemical reaction
- activated complex / transition state
- the particular arrangement of atoms at the top of the barrier
- frequency factor
- related to teh frequency of collisions and the probability that the collisions are favorably oreinted for the reaction
- reaction mechanism
- the process by which a reaction occurs
- unimolecular
- an elementary reaction that involves a single molecule
- bimolecular
- an elementary that involves two molecules
- termolecular
- an elementary reaction three molecules
- rate-determining step
- teh slow step limiting the overall reaction rate
- catalyst
- substance that chnages the speed of a chemical reaction without undergoing a permanent chmical change itself in teh process
- homogenous catalyst
- a catralyst that is present in teh same phase as the reacting molecules
- heterogenouse catalyst
- a catalyst that is in a different phase from that of the reactant substances
- adsorption
- the binding of molecules to a surface. usually the initial step in heterogeneous catalysis
- active sites
- the places where reacting molecules may become adsorbed
- enzymes
- a protein molecule that acts to catalyze specific biochemical reactions
- substrates
- the substances that undergo reaction at the active site
- lock-and-key model
- simple explanation for the specificity of enzymes
- chemical equilibrium
- occures when opposing reactions are proceeding at equal rates
- homogenous equilibria
- equilibria involving substances all in the same phase
- heterogenous equilibria
- equilibria involving substances in different phases
- reaction quotient
- the value that is obtained when concentrations of reactants and products are inserted into the equilibrium expression.
- Le Châtelier's principle
- if a system at equilibrium is disturbed by a change in temperature, pressure, or the concentration of one of the components, the system will shift its equilibrium position so as to counteract the effect of the disturbance.
- Bronsted-Lowry acid
- an acid can transfer a proton to another substance
- Bronsted-Lowry base
- a base can accept a proton
- conjugate acid
- formed by the addition of a proton to the base
- conjugate base
- formed by the removal of a proton from the acid
- polyprotic acids
- acids that have more than one ionizable H atom
- amines
- a compound that has the general formula R3N where R may be H or a hydrocarbon group
- hydrolysis
- a reaction with water. when a cation or anion eracts with water, it changes teh pH
- amphoteric
- capable of acting as either acids or bases
- carboxylic acids
- acids that contain a carboxyl group
- Lewis acid
- an electron-pair acceptor
- Lewis base
- an electron-pair donor
- common-ion effect
- the dissociation of a weak electrolyte is decreased by adding to the solution a strong electrolyte that has an ion in common with the weak electrolyte
- buffered solutions / buffers
- solutions that resist a change in pH upon addition of small amounts of acid or base
- buffer capacity
- the amount of acid or base the buffer can neutralize before the pH begins to chnage to an appreciable degree
- complex ion
- an assembly of a metal ion and the Lewis bases bonded to it
- qualitative analysis
- determines only the presence or absence of a particular metal ion
- quantitative analysis
- determines how much of a fiven substance is present
- spontaneous
- processes that occur without any outside intervention
- reversible process
- a process that can go back and forth between states along exactly the same path. a system at equilibrium is reversible becasue it can be reversed by an infinitesimal modification of a variable such as temperature
- irreversible process
- a process that cannot go back and forth between thermodynamic states along exactly the smae path. any spontaneous process
- second law of thermodynamics
- there is an inherent direction in which processes occur
- isolated system
- system that doesn't exchange energy or matter with its surroundings
- translational motion
- movement in which an entire molecule moves in a definite direction
- vibrational motion
- atoms within a molecule move periodically toward and away from on another
- rotational motion
- movement of a molecule as though it is spinning like a top
- Third law of thermodynamics
- the entropy of a pure crystallin substance at absolute zero is zero
- standard molar entropies
- the molar entropy values of substances in tehir standard states
- Gibbs free energy
- a thermodynamic state function that combines enthalpy and entropy.
- oxidizing agent / oxidant
- removes electrons from another substance by acquiring them itself
- reducint agent / reductant
- substance that gives up electrons causing another substance to be reduced
- half-reactions
- equations that show either oxidation or reductino alone
- voltaic/galvanic cell
- device in which the transfer of electrons takes place through an external pathway rather than directly between reactants
- anode
- electrode at which oxidation occurs
- cathode
- electrode at which reduction occurs
- electromtive force
- (emf) the potential difference between the two electrodes of a voltaic cell providing the driving force that pushes electrons through the external circuit
- concentration cell
- a cell based solely on the emf generated because of a difference in a concertration
- battery
- a portable, self-contained electrochemical power source that consists of one or more votaic cells
- cathodic protection
- protection of a metal by making it the cathode in an electrochemical cell
- electrolysis reaction
- a reaction in which a nonspontaneous redox reaction is brought about by the passage of current under a sufficient external electrical potential
- electrolytic cells
- place where electrolysis reactions occur
- nucleons
- subatomic particles in the nucleus, protons and neutrons
- radionuclides
- nuclei that are radioactive
- radioisotopes
- atoms that contain radionuclides
- alpha particles
- particles that are identical to helium-4 nuclei, consisting of two protons and two neutrons
- beta particles
- energetic electrons emitted from teh nucleus
- gamma radiation
- consisting of high energy photons, electromagnetic radiation of very short wavelength.
- positron
- a particle that has the same mass as an electron but an opposite charge
- electron capture
- the capture by the nucleus of an electron from teh electro cloud surrounding the nucleus
- radioactive series / nuclear disintegration series
- a series of nuclear reactions that begins with an unstable nucleus and terminates with a stableone.
- magic numbers
- numbers of protons and neutrons that result in very stable nuclei
- nuclear transmutations
- a conversion of one kind of nucleus to another
- particle accelerators
- a device that uses strong magnetic and electrostatic fields to accelerate charged particles
- transurnaium elements
- artificial transmutations that produce elements with atomic number above 92
- activity
- the rate at which a sample decays
- geiger counter
- device used to detect and measure radioactivity
- scintillation counter
- used to detect and measure radiation
- radiotracer
- a radioisotope that can be used to trace the path of an element
- nuclear binding energy
- the energy required to separate a nucleus into its individual nucleons
- fusion
- the joining of two light nuclei to form a more massive one
- fission
- the splitting of a large nucleus into two smaller ones
- chain reactions
- a series of reactions in which one reaction initiates the next
- critical mass
- teh amount of fissionable material large enough to maintain teh chain reaction with a constant rate of fission
- supercritical mass
- a mass in excess of a critical mass
- ionizing radiation
- radiation that causes ionization
- nonionizing radiation
- radiation that does not cause ionization
- free radical
- a substance with one or more unpaired electrons
- alkanes
- hydrocarbons that contain only single bonds
- alkenes
- hydrocarbons that contain a Carbon Carbon double bond
- Alkynes
- hydrocarbons that contain a Carbon Carbon triple bond
- aromatic hydrocarbons
- carbon atoms are connected in a planar ring structure
- structural isomers
- compounds with teh same molecular formula but with different bonding arrangements
- geometric isomers
- compounds that have teh same molecular formula nd teh same groups bonded to one another but differ in the spatial arrangment of these groups
- addition reactions
- a reactant is added to the two atoms that form the multiple bond
- substitution reactions
- one atom of a molecule is removed and replaced by another atom or group of atoms
- functional group
- a site of reactivity in an organic molecule
- ethers
- compounds in which two hydrocarbon groups are bonded to one oxygen
- carbonyl group
- Carbon Oxygen double bond
- aldehydes
- carbonyl group with at least one H atom attached
- ketones
- carbonyl group occurs at teh interior of a carbon chain
- saponification
- the hydrolysis of an ester in the presence of a base
- ester
- compounds in which the H atom of a carboxylic acid is replaced by a hydrocarbon group