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CHEM 1133 Ch. 20.1
CHEM 1133 Ch. 20.1
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Chemistry
Undergraduate 2
03/13/2011

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Term
Spontaneous change
Definition
A chemical or physical change that occurs by itself under specified conditions without a continuous input of energy from outside the system
Term
Non-spontaneous change
Definition
A physical or chemical change that occurs only if the surrounding supplies the system with a continuous input of energy.
Term
The second law of thermodynamics
Definition
All real processes occur spontaneously in the direction that increases the entropy of the universe.
Term
The third law of thermodynamics
Definition
A perfect crystal has zero entropy at a temperature of absolute zero.
Term
Prediction of relative S° values of a system
Definition

 

  1. S° increases as temperature increases
  2. S° increases as a substance changes from solid to liquid to gas 
  3. S° of a dissolved solid or liquid is greater than the S° of the pure solute. This is not necessarily the case for ionic solutions since the water molecules may inhibit ions from an increased microstate. 
  4. The S° of a gas decreases when it dissolves in an aqueous solution. The entropy of a gas increases however when dissolved in another gas due to the separation and mixing of gas molecules. 
  5. Heavier molecules have larger S° values.
  6. For allotropes the entropy is higher for for more atoms that allow more freedom of motion.
  7.  S° increases with chemical complexity.
  8. The physical state of a compound dominates the complexity.

 

 

Term
Solubility
Definition
The maximum amount of solute that can dissolve in a given volume of solvent @ a given temperature. 
Term
Molar solubility 
Definition
Number of moles of solid dissolved per liter liter of solution
Term
The common ion effect
Definition
The solubility of a salt is less in the presence of a common ion already present in the solution as is predicted in Le Cheatliers principle.   
Term
How to find pH at which a medal hydroxide ionic solution precipitates:
Definition

  1. Write the Ksp equation for the ions based on their coefficients when dissolved.
  2. Locate the Ksp value and set it equal to ionic equation.
  3. Plug in molarity of medal ion. 
  4. Solve for hydroxide ion.

Term
How to find the molarity of an ionic medal in a medal hydroxide ionic solution given the solutions pH:
Definition

  1. Write out the Ksp equation.
  2. Find concentration of OH- via 14-pH=pOH, 10-pOH=[OH-].
  3. Determine Ksp (given in appendix).
  4. Solve for ionic medal.

Term
How to find the percent ionic medal left in a solution after its concentration has been changed (for example due to precipitation by addition of pH etc.):
Definition

Percent concentration left in solution:

[(Current concentration)/(initial concentration)](100)

Term
Formation constant:
Definition
The equilibrium constant for the one step formation of a complex ion from a metal ion and its ligands.
Term
Coordinate covalent bond:
Definition
A bond between two atoms in which one atom contributes both electrons.
Term
Saturated
Definition
When the maximum amount of solute has been dissolved the solution is saturated.
Term
Supersaturated
Definition
An unstable solution with more solute dissolved compared to normal levels of saturation.
Term
Insoluble
Definition
A substance that won't dissolve in a solution. 
Term
Solubility product constant (Ksp)
Definition

The equilibrium constant for a solid dissolving into ions.

 

Ksp = products/reactants

 

Since reactants are solids and solids are not included in equilibrium calculations there is no denominator and on products are multiplied and raised by their coefficient.

Term
Situation where Ksp's of salts cannot be compared to determine which is more soluble
Definition
In cases where the stoichiometry is not 1/1. 
Term
Crystal field theory
Definition
A theory developed to explain the character in color and magnetism of complex ions by explaining the effect the d orbital influence on the ligands.
Term
Crystal field splitting energy (∆)
Definition
The magnitude of splitting of the d orbital affected by the binding of ligands to a metal ion.
Term
Strong field ligands vs. weak field ligands
Definition
Stronger field ligands cause a larger split of the d orbital when creating a complex ion with the metal ion.
Term

High spin vs. low spin complexes

Definition

High spin complexes: created by weak crystal fields, such complex ions contain the least amount of unpaired electrons.

 

Low spin complexes: created by strong crystal fields, such complex ions contain the maximum amount of unpaired electrons.

Term
Chemical kinetics
Definition
The study of reaction rates, the changes in concentrations of reactants (or products) as a function of time. 
Term
Four factors that affect the rate of a given reaction
Definition

  1. Concentration of reactants: the more frequently reactants collide the faster a reaction occurs; therefore, an increase in concentration will increase the number of collisions between reactants which will increase the rate of the reaction.
  2. Physical state of reactants: the more exposed reactants are to one another the faster the reaction due to a higher number of collisions. For example, wood chips burn faster than a wooden log because there is more surface area exposed in the mulch. 
  3. Temperature of environment: increasing temperature increases the number of collisions between reactants; however, more importantly, increased temperature increases the kinetic energy of the molecules that collide. Kinetic energy is of significant importance because reaction are dependent on kinetic energy. If the kinetic energy of a collision is not adequate, chemical reactions between reactants may not occur.
  4. The use of a catalyst.

Term

Reaction rate

Definition
The changes in concentrations of reactants or products per unit time.
Term
Instantaneous rate
Definition
The rate at a particular instant in a reaction.
Term
Initial rate
Definition
The instantaneous rate of a reaction at the moment the reactants mix.
Term
The rate law (rate equation)
Definition

The rate law expresses the rate as a function of reactant concentrations, product concentrations , and temperature. The components of the rate equation include the rate constant and the reaction order. The rate law is deduced by calculating the initial rate of a reaction, using initial rates from several experiments to find the reaction orders, using the values obtained from the initial rate and and reaction order to find the rate constant. 

Term
The rate constant
Definition

A constant specific for a given reaction and is not changed by the stage in the reaction.

Term

Reaction orders

Definition

Define how the rate is affected by reactant concentration. The reaction orders are not derived from a reactions stoichometry (coefficients) but from rate data. Reaction orders cannot be negative or fractions; they are zero or positive integers. 

Term
Three ways to determine the initial concentration rate
Definition

  1. A change in color due to the production or elimination of color.
  2. A change in pressure if there is an increase or decrease in gaseous moles of a substance. 
  3. A change in conductivity when a reactions conductivity changes as it proceeds.

Term
Transition metals with electron configuration exceptions:
Definition

  1. Cu: [Ar]4s13d10

Term
How to predict the effect of solubility by the introduction of acid
Definition
  1. If the precipatite produces hydroxide (when in aqueous form) than the hydroxide will react with the hydronium to produce water. The reaction will proceed to the right (more precipitate will dissolve) because solute evolved into water.
  2. If a component of the of the precipitate is a weak base in aqueous form than the weak base will react with hydronium to form water. The reaction will proceed to the right as more product evolved (more precipitate will dissolve).
  3. If the dissolved precipitate is not a weak base (eg. strong base) the reaction will not be effected when hydronium is dissolved.
Term
How to caluclate the solubility of a precipitate when given Ksp
Definition
  1. Write out the reaction when the precipitate dissolves.
  2. Write the Ksp equation
    • Treat coffecients by multiplying and raising to the power by the coefficient.
    • Let solute components equal S.
  3. Solve for S (solubility).

 

Term
How to solve for solubility given a precipitates Ksp and an initial concentration of one of the solutes (the common ion effect)
Definition
  1. Write out the solubility.
  2. Set up a reaction table with S as unknown and ion already present added to unknown.
  3. Find theoretical concentrations at equilibrium.
  4. Solve for S (solubility).
Term
Find Ksp given solubility values
Definition
  1. Convert solubility to molar solubility.
  2. Write out reaction table based on coefficients.
  3. plug into Ksp (Ksp = [2A]^2[B]) reaction equation.
  4. Solve for Ksp.
Term
Complex ion
Definition
A central metal ion covalently bonded to two or more anions or molecules.
Term
Ligands
Definition
The anions or neutral molecules bonded to an ionic metal in a complex.
Term
Integrals of the 1st 2nd and 3rd order
Definition

  1. First order integral: x
  2. Second order integral: ln(x)
  3. Third order integral: 1/x

Term
Solubility rules
Definition

  1. Soluble:
    1. Group 1 alkali metals are soluble.
    2. Ammonia (NH4) is soluble.
    3. Nitrates, acetates, and chlorates are soluble.
    4. Br, Cl, F, and I are soluble except when mixed with Ag, Pb, Cu, and Hg.
    5. All sulfates (SO4) are soluble except when Ba, Sr, Ca, Ag, and Pb.
  2. Insoluble compounds:
    1. All Hydroxides are insoluble except when bonded to group 1 metals or large group two metals (Ca and bigger).
    2. Phosphates, carbonates are insoluble except when bonded with group 1 metals and NH4. 
    3. Sulfides are insoluble except when bonded to group 1, 2 metals, or NH4. 
  3. Remember:
    1. The larger the charge of the ions in an ionic compound, the less soluble the compound.
    2. Cues for soluble compounds: group 1 metals, 2 metals, NH4, nitrate, and sulfate, halogens (Br, I, Cl, F), acetates, perchlorates.
    3. Insoluble: Hydroxides, carbonate, phosphate, sulfide, Pb, Ag, Cu, Hg.

Term
Classifying acids and bases (strong vs. weak)
Definition

  1. Strong acids:
    1. Halogens HBr, HCl, HI (excluding HF which is weak).
    2. Oxoacids: 2 or more oxygens than hydrogens (H2SO4, HNO3, HPO3, HClO4). 
  2. Weak acids:
    1. Acids where the hydrogen is not bonded to the oxygen.
    2. Oxoacids with 1 oxygens/ 1 hydrogen ratio.
    3. Carboxylic  acids.
  3. Strong bases:
    1. Hydroxide compounds.
    2. Compounds containing oxygen with a negative two charge.
  4. Weak bases:
    1. Compounds with electron rich nitrogens (example: NH3 (ammonia) and amines.

Term
First integrated law
Definition
ln([A]0/[A])t = kt
Term
Fraction of reactant decomposed in a RxN with concentration change over time
Definition

([A]0-[A]t)/[A]0

 

Term
Half life
Definition
The time required for a reactant's concentration to reach half its initial value.
Term
The time it takes to reach one half life
Definition
t=ln(2)/k
Term
Half life of a first order reaction
Definition
t(1/2)=ln(2)/k
Term
Half life of a second order reaction
Definition
t(1/2)=1/(k[A]0)
Term
Half life of a zeroth order reaction
Definition
t(1/2)=[A]0/(2k)
Term
Activation energy
Definition
The minimum energy molecules must have to react.
Term
Arrhenius equation
Definition

k=Ae^-(Ea/RT)

 

Ea/RT: gives the number of molecules at a given temperature that will have enough energy to react. 

 

A: the "pre-exponential factor"and accounts for the fact that some molecules won't form products upon interaction (for example incorrect orientation upon collision). The pre-exponential symbol expresses the number of molecules that receive an adequate amount of activation energy but do not proceed the hump to and evolve into products. 

Term
Collision theory 
Definition
The collision theory claims that reactant particles, atoms, molecules, and ions, must collide in order to react.
Term
Radioactivity - Ch. 23.1
Definition

Decay, of an unstable nucleus, by emitting radiation.

Term

Nucleons (23.1)

Definition
Elementary particles, the protons and neutrons, that make up the nucleus.
Term
(23.1) Nuclide
Definition

A nuclear with a specific number of two types of nucleons. When an element has two isotopes, each isotope is a unique number of neutrons but the same number of protons. 

Term
Isotopes
Definition

Atoms with a characteristic number of protons but a different number f neutrons. 

Term
Chemical changes vs. nuclear reactions
Definition

  1. Electrons involved in chemical reactions vs. protons, neutrons and subatomic particles involved in nuclear reactions.
  2. In chemical reactions substances are changed; in nuclear reactions atoms are changed.
  3. Chemical reactions are accompanied by relatively small changes in energy vs. nuclear reactions are accompanied by relatively large quantities of energy.
  4. Chemical reaction rates are influenced by temperature, catalysts, concentration, and the compound at hand. Nuclear reaction rates are influenced mainly by the number of nuclei and only on rare occasions by element/compound at hand. 

Term
(18.2) Number of of sigfigs
Definition
The number of sig figs in a concentration equals the number of sigfigs to the right of a pH/pOH decimal.
Term
(18.1) Arrhenius acid - base definition
Definition

  • An acid is any substance that has H+ ions in it yields hydronium in water.
  • A base is a substance that has OH in its formula and dissociates in water yields OH. 

Term
(18.1) Neutralization
Definition
When H ions and OH ions combine to form H2O.
Term
(18.2) Comparison of hydronium in different solutions
Definition
a pH of one is 10 times stronger than a pH of 2 and 100 times stronger than a pH of 3. 
Term
(18.2) The relations among pH, pOH, and pKw
Definition

Kw = [H30+][OH-] = 1e-14

 

pKw = pH+pOH = 14

 

 

Term
(18.2) Acid base definition of Arrhenius vs. Bronstead lowry vs. lewis
Definition

Arrhenius acid base definition: an acid is any molecule that contains a hydrogen ion and dissociates ions into H+ in aqueous solutions. A base is any compound containing a OH- complex that dissociates into OH- ions when in aqueous solution.

 

Bronstead lowry definition: An arrhenius and Bronstead lowry acid are the same. A Bronstead Lowry base accepts H+ in aqueous solutions and other situations.

 

Lewis acid base definition: An acid is any compound that donates accepts a lone pair of electrons. A base is any compound that donates a pair of lone electrons. 

Term
(18.3) Conjugate acid base pairs
Definition

HS- and H2S

 

NH3 and NH4

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