par Vraj Rao Il y a 3 années
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Plus de détails
Solubility (Qsp)
Precipitate
An insoluble product that forms from a reaction between 2 soluble ionic compounds
Molar Solubility
The amount (in moles) of solution in 1L of saturated solution
Titrations
#3. Use Kw to calculate the concentration and find pH
#2. Determine the excess moles and new concentration
#1. Calculate the moles of Acid/Base
Equivalence Point
The point in a Titration where the amount of Acid present exactly equals and reacts with amount of Base present
A-B Titration Curve
A graph of pH of an acid/base solution vs Amount of ADDED acid/base
Amphiprotic Substances
Can act as an acid or a base
A molecule/ion which can accept/donate a proton
#3. Re-calculate the concentration of the acid/base using the excess moles and the combined volume
#2. Find the difference between the two values and determin which one has excess
#1. Determine the MOLES of both, acid and base
Ratio of concentration comparing ionized acid/base at EQLBM to original concentration of acid/base
% Dissociated = ( {}dissociated / {}initial ) *100%
Kb = Base-Dissociation Constant for the Ionization of a Base
Ka < Kb = solution is Basic
Ka = Acid-Dissociation Constant for the Ionization of an Acid
Ka > Kb = solution is Acidic
Kw = (Ka)*(Kb)
Can be re-arranged to solve for missing K_ value
#4. Calculate the Percent Dissociation
#3. Create and solve teh EQLBM expression
#2. Setup the RICE table and add values
#1. Calculate the concentration using pH
The conjugate base of a Strong Acid is a weak base
A base that has LIMITED dissociation in water
A base that COMPLETELY dissociates into ions in water
The conjugate acid of a Strong Base is a weak acid
Weak
An acid that has LIMITED dissociation in water
Strong
An acid that COMPLETELY dissociates into ions in water
Bronsted-Lowry Theory
Conjugate
Conjugate Base
The particle remaining after a proton LEAVES an ACID
Conjugate Acid
The particle formed after a proton JOINS a BASE
Acid-Base Pair
A pair of 2 substances related by the gain/loss of protons
A proton Acceptor
A proton DONOR
Arrhenius Theory
Base
A substance that contains HYDROXIDE ION (OH-) in its chemical formula
pH level above 7
Acid
A substance that contains HYDROGEN in its chemical formula
Ionizes in water to form HYDRONIUM ION
pH level below 7
RICE Table
E = EQLBM value = Initial Amount - Change Variable
Solved using Keq = {products} / {reactants}
C = Change = Use variables
I = Initial Amounts (in concentration)
R = Reaction
Changes in Substances
Removing products
Adding products
Removing reactants
Shift to reactants side
Rf < Rr
Adding reactants
Shift to products side
Rf > Rr
EQLBM Constant Expression
#3. Substitute the respective values and solve
#2. Write the EQLBM expression
#1. Calculate the molar concentrations
K = {products} / {reactants}
let the EQLBM sign be represented as {=}
K = {C}^c + {D}^d / {A}^a + {B}^b
E.G. aA + bB {=} cC + dD
AKA Law of Chemical EQLBM , AKA Law of Mass Action
Concentration
{C} = solute / solution
Heterogeneous
An EQLBM system in which the components are in DIFFERENT physical states (e.g. gas, aqueous, solid, liquid)
Homogeneous
An EQLBM system in which all the components are in the SAME physical state (e.g. gas, aqueous, solid, liquid)
Dynamic
Chemical (an example of Dynamic)
The state where the reaction vessel contains a mixture of all the reactants and products
One in which there is motion, despite there being no Net Change
Static
One in which there is NO motion
When a system at EQLBM is stressed, the syste, works to restore EQLBM once again
Types of Stress
Changes to the Pressure
Only affects EQLBM systems with unequal moles of Gaseous reactants and products
Changes to the Temperature
When temperature is decreased, Exothermic reactions are favoured
Consider HEAT as a Product in Exothermic Reactions
A + B = AB + Heat
Shifts to Products side
Shifts to Reactants side
When temperature is increased, Endothermic reactions are favoured
Consider HEAT as a Reactant in Endothermic Reactions
A + B + Heat = AB
If heat is removed
Shift to Reactants side
If heat is added
Shift to Products side
Changes in Concentration
System shifts to get back to the same ratio of reactants and products
Means that Keq is constant
At a given temperature, the reactants and products with ALWYAS be in the SAME RATIO at EQLBM, no matter the starting point
The Reactants are ALWAYS on the LEFT, and the Products are ALWAYS on the RIGHT side of an equation
All substances present are being made and unmade at the same rate
EQLBM constant K
Magnitude
Since products are divided by reactants in the expression:
A smaller K value (<1)
RVS reaction is favoured
A larger K value (>1)
FWD reaction is favoured
Dependence
Depends on the EQLBM concentrations
Depends on Temperature
Doesn't depend on the initial concentrations
Doesn't depend on the Reaction Mechanism
Generally, an equilibrium is a state of balance
RVS reactions occur slowly during the start, then speed up as product concentrations increase
FWD reactions occur rapidly during the start, then slows down as reactant concentrations decrease
The reactant and product concentrations are CONSTANT, not equal
Both reactions occur until the concentrations of reactants AND products undergo no further change
Represented by an "equal sign" which has an arrow pointing the opposite direction on each line
Theoretically, all reactions are reversible
Reactions written R-L are RVS reactions
Reactions wrtiten L-R are FWD reactions
#3. The unknown Ox. Numbers can be assigned algebraically and be solved using variables
#2. The total Ox. Numbers of a molecule/ion is the value of the charge of the molecule/ion
For neutral compounds, the Ox. Number of all the atoms must add up to ZERO
#1. Assign common Ox. Numbers
Use the Periodic Table of Elements
#7. The sum of all the Ox. Numbers of all the elements in a polyatomic ion equals the charge on the ion
#6. The sum of the Ox. Numbers of all the elements in a compound is ZERO
#5. In covalent compounds that do not contain "H" or "O" the more EN element is assigned an Ox. Number that equals the negative charge it usually has in its ionic compounds
#4. The Ox. Number of Oxygen in its compounds is usually -2, but there are certain exceptions
#3. The Ox. Number of Hydrogen in its compounds is +1 except in metal hydrides, where the Ox. Number of Hydrogen is -1
#2. The Ox. Number of an element in a monotomic ion equals the charge of the ion
#1. A pure element has an Ox. Number of ZERO
An arbitrary system based on charge of ions and EN
Used to keep track of electrons during reactions
A balanced chemical equation that shows the number of electrons involved
To monitor the transfer of electrons, represent each reaction seperately
Reducing Agent
Therefore, this reactant is OXIDIZED
The reactant which causes the other to be REDUCED
Oxidizing Agent
Therefore, this reactant is reduced
The reactant which causes the other to be OXIDIZED
LEO the lion says GER
Gain of Electrons - Reduction
Loss of Electrons - Oxidation
The atom/ion that GAINS electrons
The atom/ion that LOSES electrons
Reduction
From metallurgy - producing metals from their compounds
Oxidation
Reaction of substances with oxygen (combustion OR corrosion)
At the end, the equation can be confirmed by counting all the atoms and charges on each side and making sure they are balanced
#3. Complete the Net Ionic Equation
All the spectator ions (those which are the same on both sides of the equation) cancel out, and the final equation is written from the remaining components
#2. Turn the chemical equation into an Ionic equation
All the aqueous are separated into its component ions
#1. Chemical equation
Normal equation written in the chemical names
Predicting Mechanisms
#3. All the elementary steps must add up to the overall equation
#2. The slowest step (Rate-Determining-Step) must be consistent with the rate equation
#1. Each step must be elementary
Involve no more than 3 reactant molecules
Only best guesses at the behaviour of molecules
The overall reaction can only be as fast as the slowest elementary process (AKA Rate-Determining-Step)
Occur over a set of stpes
Each step of the mechanism is known as "Elementary Process"
Rate Law Exponents
Exponents are related to the "Order of the Reaction"
Order of the Reaction
Overall order = m
Unit of K = L ^(m-1) / mol ^(m-1) *s
The sum of the rate law exponents
Experimentally determined by changing 1 reactant at a time and looking at how the reaction rate changes
Rate Equation
rate = K {A}^x {B}^y
Exponents of the Rate Law are NOT related to the coefficients, of the balanced chemical equation in any way
K = the rate constant, determined by the reaction and the conditions the experiment was conducted in
The x and y values are determined by the actual experiment
In the sense where A+B = C + D
Rate is measured in moles per litre per second (mol/L*s)
rate = delta concentration / delta time
#5. Catalyst
It lowers the amount of required energy for the reaction to occur
Also known as Activation Energy
A compound that increases the rate of a chemical reaction without being consumed in the actual reaction
#4. Temperature
Increased temperature is due to increased particle motion
Greater the motion of a particle, the greater the chance it will encounter another reactant
Higher the temperature = Higher the reaction rate
#3. Concentration
More chemicals result in more particles which can participate in the reaction
Higher the concentration = Higher the reaction rate
#2. Surface Area
Increase in surface area = Increase in the reaction rate
Homogeneous Reaction
All the reactants are in the same phase/state
Heterogenous Reaction
The reactants are in different phases/states
#1. Chemical Nature
Alkali metals later founds (first found only in compounds)
Due to high reactivity
Precious metals are discovered first
Not very reactive
Reactions that require a GREATER number of particles to collide at the same time will DECREASE the chances of a successful reaction to occur
Rate Theories
Catalysts
Transition State
Collisions
Chemical reactions indicate the overall changes that is observed
How quickly reactants disappear to form products
#4. Add the equations and enthalpies together (cancel out any repeating chemicals)
#3. Multiply the equations by factors such that they match the desired equation (multiply the enthalpies by the same factor)
#2. Arrange the equations so that your desired reactants are on the LEFT side and the products are on the RIGHT side
#1. Number each given thermochemical equation
Rules
#3. When cancelling compounds for Hess's Law, the state of the compounds is really important
#2. When a reaction is reversed, the sign of "H" must also be reversed
#1. If all the coefficients of an equation are multiplied/ divided by a common factor, the "H" must be changed likewise
The "H" is the same as the sum of the values of the "H" for each individual step
Enthalpy of Formation (delta Hf)
The (delta Hf) for elements in their standard states are ZERO
delta H = sum of (delta Hf of products) - sum of (delta Hf of reactants)
The amount of heat absorbed/released when 1 mole of the substance is formed at standard temperature (25 degrees Celsius) from its elements in their standard states
Molar Enthalpy
The change in enthalpy on a per-mole basis
Enthalpy
Total kinetic and potential energy of a system at a constant pressure
Heat Capacity
c = heat capacity (in Joules/Celsius) q = quantity of heat transferred (in Joules) delta T = temperature (in degrees Celsius)
c = q/T q= cT
The amount of heat transfer required to raise the temperature of a sample by 1 degree Celsius/Kelvin
Specific Heat Capacity (c)
c = specific heat capacity (in Joules/Grams*Celsius) q = quantity of heat transferred (in Joules) m = mass (in grams) delta T = temperature (in degrees Celsius)
c = q/mT q=mcT
The amount of heat transfer required to change the temperature of 1 gram of a substance by 1 degree Celsius/Kelvin
Energy cannot be created or destroyed
The total amount of energy in the universe is constant
Temperature
The measure of internal energy of an object due to particle motion (kinetic energy)
Heat
The transfer of energy due to contact
Calorimetry
A calorimeter is used to perform this task, while a Bomb Calorimeter is a high tech version of this
The measure of heat change due to a chemical reaction
Changes in a System
Exothermic Reaction
If the system releases energy and the surroundings gain energy
Endothermic Reaction
If the system absorbs energy and the surroundings lose energy
Different types of matter require different amount of Heat Transfer to change the same temperature
Water is unusual - it can absorb/release a lot of hear without the temperature drastically changing
All chemical reactions result in Heat Transfer
Understanding heat transfer properties is important for building sufficient materials
Ethers
#4. Join the "oxy" branch to the larger Hydrocarbon group
Listed in alphabetical order
#3. Consider the smaller hydrocarbon group to be a branch that contains "O"
Add "oxy" to the root
#2. Give the longest Alkyl group an appropriate hydrocarbon name
Include any branches / other functional groups as necessary
#1. Identify the longest Alkyl group as the Parent alkane
2 Alkyl groups (the same or different) attached to an "O" atom
Formed by Condensation reaction, when 2 alcohol molecules react
Amides and Amines
Organic compounds that contain "N"
Amide
#2. Replace the "-oic acid" ending of the Parent acid with "-amide"
#1. Locate the part of theAmine that contains the C=O group and name the Parent Carboxylic acid that this part derives from
Keep in mind, the C=O group is ALWAYS given the number 1 position
Amine
#3. Include the position number if required
#2. Replace the "-e" at the end of the Parent Alkane with "-amine"
#1. Identify the largest Alkyl group attached to the "N" atom as the parent Alkane
Esters
#2. Convert the "oic acid" ending of the carboxylic acid to "oate"
#1. Convert the suffix "(a)nol" ending of the alcohol to "yl"
Made by joining an Alcohol and a Carboxylic Acid - 2 parts, 1 comes from each
Ketones
#4. Any substituents are named as per usual rules
#3. Indicate the position of the Carbonyl using the L.P.N. coefficient
#2. Remove the "e" and add the "one" as the ending
Carbonyl group is attached to a C that is not at the end
Aldehydes
#4. Branches are named as per usual rules
#3. This carbonyl group is assigned as C-1
#2. Remove the "e" and add "al" as the ending
#1. Take the longest chain containing the Carbonyl group
Carbonyl group is attached to the end C
Phenol
When benzene contains 1 single hydroxyl group the common name is used as its UIPAC name
Alcohol
Classifications - according to the type of Carbon to which the "-OH" group is attached
Tertiary (3)
Secondary (2)
Primary (1)
#3. Alcohol suffix comes after the Hydrocarbon suffix, minus the "e"
E.G. Methene + -ol = Methanol
#2. Chain is numbered so as to give the alcohol unit the L.P.N.
#1. Root name based on longest C chain with -OH attached
Contains the hydroxyl group (-OH)
Can be prepared by adding Water to an Alkane
Zaintsey's Rule
The poor get poorer
Common place amongst alcohols and alkyl halides
The reverse of an Addition reaction (double bond is usually formed)
Markovnikov's Rule
The rich get richer
Alkenes & Alkynes have a greater tendency to undergo this reaction
Hydrogen, Halogens, Hydrogen Halides, and Water can be added
C-C bonds in Alkanes are difficult to break
Usually "H" replaced by a Halogen atom
An "H" atom(s) are substituted by a different atom(s)
First Point of Difference
Alphabetical order
Line diagram
Vertex of each line is a carbon, Hydrogens not mentioned
Condensed diagram
Understood as carbons are beside carbons (short forms used)
Structural diagram
Similar to Lewis diagrams
Alkynes (-YNE)
#2. Location number
#1. Number of C in longest chain
Hydrocarbons with triple bonds
Alkenes (-ENE)
Trans-
Longest C chain forms Z shape
If the 2 alkyl groups, C, of the parent chain are on the OPPOSITE side of C=C
Cis-
Longest C chain forms U shape
If the 2 alkyl groups, C, of the parent chain are on the SAME side of C=C
Where there's more than 1 double bond, add "a" to the end of the prefix (e.g. meth=metha)
lowest numbers are Priority
#3. Suffix family
#2. Insert the number for where the double bond is located
#1. Root name = longest continuous C chain, with double bonds
Hydrocarbons with double bonds
Alkanes (-ANE)
Other "Add-ons"
Aromatic Hydrocarbons
Contain a benzene ring as a base
PARA
P-
META
M-
ORTHO
O-
Structural Isomers
Compounds with the same molecular formula but with different bonding arrangements
Haloalkanes
Alkanes with halogen atoms
Cycloalkane
Ring like structure of alkanes
#3. Identify which numbers of substituents are connected to the C chain
#2. Find all the substituents and name them correctly from the chart
#1. Find the longest C chain and number them appropriately in ascending order (find the correct name from the chart)
Hydrocarbons with single bonds
#3. Assign numbers (locants) to the principal functional group as lowest common chain
#2. Identify the root (longest continuous chain of Carbons)
#1. Identify the suffix
Suffix: The functional group
Suffix Names:
Root: The number of Carbons in the largest chain
Root Names:
*insert pic*
Carbon allows diversity
It can makes 4 bonds: a combination of Single, Double, or Triple bonds
56,204,570 organic substances have been recorded to date
Number of hybrid orbitals that form = Number of atomic orbitals that combined to make the hybrid orbitals
Triple Bond
Involves 1 SIGMA and 2 PI bonds
Double Bond
Involves 1 SIGMA bond and other PI bonds
Single Bond
Involves 1 SIGMA bond
#3. Concept of atomic orbital hybridization is used
#2. Should be MAX orbital overlap
#1. Region of orbital overlap has a MAX of 2 electrons
Covalent bond formation and molecular shapes based on the formation of new molecular orbitals
Covalent bond formation and molecular shapes based on orbital overlap
#5. Dispersion forces
#4. Dipole-Induced Dipole interactions
#3. Ion-Dipole interactions
#2. Dipole-Dipole interactions
#1. Hydrogen bonding
4 Categories
Occurs because NP molecules spontaneously form temp. dipoles
Weak attraction between all molecules
Dipole-Induced Dipole
Attraction between an ion and a temp. dipole of a NP molecule
Attraction between a polar molecule and a temp. dipole of a NP molecule
Possible to induce formation of dipoles in NP molecules
Electrons in atoms are in constant motion
Ion-Dipole
Can occur between
Polar molecule (positive end) and anion
Polar molecule (negative end) and cation
Cations usually smaller than anions
Attraction between partial charges of polar molecules/ions
Dipole-Dipole
Contribute to higher melting/boiling points in polar molecules
Polar molecules are more attracted to each other than similar N-P molecules
Attraction between opposite partial charges of polar molecules
Forces exerted between molecules/polyatomic ions
Forces of attraction/repulsion between molecules
Influence physical properties of substances
Forces excerted within a molecule/polyatomic ion
When bonding is polar
a bond dipole is created
The less EN atom has a partial positive charge
The more EN atom has a partial negative charge
When 2 atoms bond
Sharing of a pair of electrons can be polar, non-polar, or ionic
Use electronegativity to predict the polarity of each bond
#4. Draw in teh bond dipoles
#3. Add electronegativity of the atoms and assign (lamda+) and (lamda-) to the bonds
#2. Draw VSEPR diagram based on Lewis structure
#1. Draw the Lewis structure
A molecule may have polar bonds but may not be polar
Types
Non-Polar Covalent
Polar Covalent
Ionic
Steps
#3. Use VSEPR Notation to determine the molecule's shape
AXmEn
A = Central atom X = Bonding set m = Number of bonding sets E = Lone pairs n = Number of lone pairs
#2. Identify the charge clouds as bonding electrons or as lone pairs
#1. Draw Lewis-Dot-Diagram for the molecule and count the number of electron charge clouds surrounding the atom
Write the chemical name of the substance and draw its valence electrons around it in a circle. Keep in mind the sharing of electron pairs in compounds
Binding Energy
Rydberg's Constant (Rh) = 2,18^10^-18 J
E = Rh/n^2
Emission Spectrum = Absorption Spectrum
Energy released when an electron falls from level 4 to 1 is the same amount of energy required for an electron to jump from level 1 to 4
delta Ejump = delta Efall
Electrons orbit the nucleus at certain discrete distances
Energy of shells increase as one proceeds away from the nucleus. Electrons only gain/lose energy by jumping from an allowed orbit to another
Specific quantities of energy/light are required for an electron to "jump" to a higher orbit - AKA - specific elements absorb specific quantities for energy/light
Orbits have defined energies called shells/levels
1880s by J.J. Balmer
WL = B (n^2/n^2-m^2)
WL = wavelength of the light emitted B = Balmer constant for Hydrogen = 364.50682 m n = integer such that n>m m = 2
Specific WL given off by the light of atoms
Loss of frequency from shattered X-ray suggests that X-rays have momentum, because light can have properties and behave like Matter
Einstein later explained
Light itself consists of individual quantum particles, called Photons
1887 by Heinrich Hertz
Certain metallic surfaces lose their negative charges when exposed to light/electricity (not the light's intensity)
Frequency of light determines how quickly the metal would lose its charge
Matter absorbed/emitted energy in whole number multiples of hv
Shows that energy can only be transferred in "packets" AKA quantum (plural is quanta)
Dispersion
As WL increases, bending decreases
The amount of bending that occurs depends on WL of light
Refraction
Whenever light goes from 1 medum to another, at an angle, the angle changes, making the light beam beng
Frequency: The number of cycles (WL) per second that passes a given point
Pattern of peaks and troughs
Trough: Botom of pattern
Peak: Top of pattern
Shows the types of ER arranged in order of decreasing wavelength
Many types of ER in addition to visible light
Carries energy through space
A type of electromagnetic radiation (ER)
Rutherford adjusted his experiment
Concluded that Hydrogen ions are fundamental particles - called them Protons
Bombarded "N" atoms, and noticed that Hydrogen ions were released
1897 by J.J. Thomson
Concluded that the rays were in fact small negatively charged particles - called them Corpuscles (we now call them electrons)
Went on the propose the Plum Pudding Model
Observed how they rays were bent by magnets, and how it could help estimate the mass of the rays
While working with cathode rays
Atomic Theory
Different elements have different atoms
All atoms of a particular element are identical
Matter is composed of indivisible particles
Law of Multiple Proportions
The masses of one element that can combine chemically with a fixed mass of another element are in a ratio of small wholes
Law of Definite Proportions
Different samples of any pure compound contain the same elements in the same proportions by mass
Law of Conservation of Mass
Mass is neither created or destroyed, only conserved
Thought experiment
After each cut, the identity would be unchanged
Eventually reach a piece that cannot be cut
Atomos
"What would happen if matter could be cut in half an infinite number of times?"
Proposed that Matter was made of 4 elements (fire, air, earth, water)
