Open System: A chemical system where matter and energy can be exchanged with the surroundings.
Closed System: A chemical system where only energy can be exchanged with the surroundings, not matter.
Reversible Reaction: A chemical reaction that can proceed in both forward and reverse directions, eventually reaching equilibrium.
Dynamic Equilibrium: A state in a closed system where the rate of the forward reaction equals the rate of the reverse reaction, resulting in constant concentrations of reactants and products.
Equilibrium Position: The relative concentrations of reactants and products in a system at equilibrium.
Activation Energy: The minimum energy required for a reaction to occur, affecting the reversibility of chemical reactions.
Collision Theory: A theory explaining chemical reactions as the result of collisions between particles with sufficient energy and proper orientation.
Le Châtelier's Principle: A principle stating that if a system at equilibrium is disturbed, it will shift to minimize the disturbance and restore equilibrium.
Equilibrium Constant (Kc): A mathematical expression representing the ratio of the concentrations of products to reactants at equilibrium, raised to the power of their stoichiometric coefficients.
Homogeneous System: A reaction where all reactants and products are in the same phase (e.g., all gases or all liquids).
Heterogeneous System: A reaction where reactants and products exist in different phases.
Acid-Base Chemistry
Acid (Brønsted-Lowry Model): A substance that can donate a proton (H⁺).
Base (Brønsted-Lowry Model): A substance that can accept a proton (H⁺).
Conjugate Acid-Base Pair: A pair of substances that differ by one proton (e.g., acid and its conjugate base).
Amphiprotic: A species that can act as both a Brønsted-Lowry acid and a base.
Buffer Solution: A solution containing a weak acid and its conjugate base (or weak base and its conjugate acid) that resists changes in pH upon the addition of small amounts of acid or base.
Dissociation Constant (Ka and Kb): Equilibrium constants representing the ionization of weak acids (Ka) or weak bases (Kb) in aqueous solution.
pH: A logarithmic scale used to measure the acidity of a solution, calculated as pH = -log₁₀[H⁺].
pOH: A measure of the alkalinity of a solution, calculated as pOH = -log₁₀[OH⁻].
Self-Ionization of Water: The process where water molecules ionize to form H⁺ and OH⁻ ions, represented by Kw = [H⁺][OH⁻].
Strong Acid: An acid that completely ionizes in water, releasing all its protons.
Weak Acid: An acid that only partially ionizes in water.
Strong Base: A base that completely dissociates in water, producing a high concentration of OH⁻ ions.
Weak Base: A base that partially dissociates in water.
Concentration: The amount of a substance in a given volume of solution, typically expressed in mol/L.
Enthalpy Change (ΔH): The heat energy change associated with a chemical reaction, influencing the effect of temperature on equilibrium.
Kw: The ionization constant of water, Kw = 1 × 10⁻¹⁴ at 25°C.
Rate of Reaction: The speed at which reactants are converted to products, relevant to equilibrium systems reaching dynamic equilibrium.
Stoichiometric Coefficients: The numbers in front of molecules in a balanced chemical equation, used in equilibrium law expressions.
Electrical Conductivity: A property used to distinguish strong and weak acids or bases by their ability to conduct electricity.
Acid-Base Titration and Analysis
pKa: The negative logarithm of the acid dissociation constant (Ka), representing the strength of a weak acid; pKa corresponds to the pH at which an indicator changes color.
pKa ± 1 Range: The pH range over which an indicator exhibits a color change due to the relative concentrations of its acidic and basic forms.
Equivalence Point: The point in a titration where the amounts of acid and base are stoichiometrically equal.
End Point: The point in a titration where the indicator changes color, signaling the equivalence point has been reached (or closely approximated).
Volumetric Analysis: Techniques and methods used to determine the concentration of an analyte by measuring the volume of a titrant required for reaction completion.
Titration Curve: A graph showing the change in pH as a titrant is added to an analyte; key features include the equivalence point, buffer region, and intercept with the pH axis.
Buffer Region: A part of the titration curve where pH changes gradually due to the presence of a weak acid and its conjugate base (or a weak base and its conjugate acid).
Standard Solution: A solution with a known concentration used in titration to determine the concentration of an unknown solution.
Mole Concept: A chemical concept used to calculate moles, mass, volume, and concentration in reactions, including titrations.
Titrant: A solution of known concentration, delivered from a burette during titration, reacting with the analyte to achieve a chemical equivalence point.
Titrand: The solution in the receiving vessel, typically of unknown concentration, reacting with the titrant in a known stoichiometric ratio.
Analyte: The substance whose concentration is to be determined, found in the titrand and reacting with the titrant via a clear chemical reaction.
Burette: A long, graduated glass tube with a stopcock, used to accurately deliver the titrant in small, controlled volumes.
Unit 3 Topic 2: Oxidation and Reduction
Redox Reactions
Redox Reaction: A chemical reaction involving the transfer of electrons, with one species being oxidized and another being reduced.
Oxidation: The loss of electrons by a chemical species during a reaction.
Reduction: The gain of electrons by a chemical species during a reaction.
Oxidizing Agent: A substance that facilitates oxidation by accepting electrons and is itself reduced.
Reducing Agent: A substance that facilitates reduction by donating electrons and is itself oxidized.
Oxidation Number (State): A number assigned to an element in a compound or ion representing the number of electrons lost, gained, or shared.
Activity Series: A list of elements organized by their ability to be oxidized, used to predict the outcome of displacement reactions.
Electrochemical Cells
Half-Equation: A balanced equation representing either the oxidation or reduction part of a redox reaction, showing electron transfer.
Electrochemical Cell: A system that converts chemical energy into electrical energy or vice versa through redox reactions.
Galvanic Cell (Voltaic Cell): An electrochemical cell where spontaneous redox reactions produce electrical energy.
Electrolytic Cell: An electrochemical cell that uses electrical energy to drive non-spontaneous chemical reactions.
Anode: The electrode where oxidation occurs in an electrochemical cell.
Cathode: The electrode where reduction occurs in an electrochemical cell.
External Circuit: A pathway that allows electrons to flow between the anode and cathode in an electrochemical cell.
Electrolyte: A substance that conducts electricity in solution by allowing ions to move and complete the circuit in an electrochemical cell.
Galvanic Cells
Cell Diagram: A shorthand representation of a galvanic cell, showing the anode and cathode, the solutions involved, and the direction of electron flow.
Salt Bridge: A device containing an electrolyte solution that maintains electrical neutrality in a galvanic cell by allowing ion exchange between half-cells.
Electrochemical Potential Difference: The voltage generated by a galvanic cell due to the difference in reduction potential between the two half-cells.
Half-Cell: One part of a galvanic cell where either oxidation (anode) or reduction (cathode) occurs, typically involving a metal electrode in a solution of its ions.
Electrode: A conductor through which electrons enter or leave a half-cell; the anode is negative (oxidation) and the cathode is positive (reduction).
Electron Flow: The movement of electrons from the anode to the cathode through an external circuit in a galvanic cell.
Ion Movement: The movement of ions in the electrolyte or salt bridge to maintain charge balance during the operation of a galvanic cell.
Standard Electrode Potential
Standard Electrode Potential (E∘): A measure of the tendency of a half-cell to gain or lose electrons under standard conditions (1 M concentration, 25°C, 1 atm).
Oxidizing Agent Strength: Determined by comparing standard electrode potentials; higher E∘ values indicate stronger oxidizing agents.
Reducing Agent Strength: Determined by comparing standard electrode potentials; lower E∘ values indicate stronger reducing agents.
Cell Potential (Ecell∘): The difference between the reduction potentials of the cathode and anode; used to predict spontaneity of a redox reaction.
Limitations of E∘: Standard reduction potentials apply only under standard conditions and may vary with temperature, pressure, and concentration.
Unit 4 Topic 1: Properties and Structure of Organic Materials
Electrolytic Cells
Electrolytic Cell: An electrochemical cell that uses electrical energy to drive a non-spontaneous redox reaction.
Electrolysis: A process in which electrical energy is used to cause a chemical change, such as the decomposition of water or metal plating.
Anode (Electrolytic Cell): The positive electrode where oxidation occurs.
Cathode (Electrolytic Cell): The negative electrode where reduction occurs.
Electrolyte: A substance that conducts electricity by allowing ions to move in solution or molten state, facilitating redox reactions.
Metal Plating: A process in which a metal is deposited onto a surface through electrolysis.
Electrolysis Products: Determined by the electrode material, nature of the electrolyte, and concentration; e.g., dilute vs. concentrated solutions of sodium chloride produce different products.
Properties and Structure of Organic Materials:
Hydrocarbon Skeleton: The carbon chain or ring structure forming the backbone of organic molecules.
Functional Group: A specific group of atoms within a molecule responsible for its characteristic chemical reactions (e.g., -OH for alcohols, -COOH for carboxylic acids).
Structural Formula: A representation showing the arrangement of atoms and bonds in a molecule, either condensed or extended.
IUPAC Nomenclature: The systematic naming of organic compounds based on rules for identifying the parent chain, functional groups, and branching.
Structural Isomers: Compounds with the same molecular formula but different connectivity of atoms.
Stereoisomers: Compounds with the same structural formula but different spatial arrangements of atoms.
Geometrical Isomerism: A form of stereoisomerism in alkenes where groups attached to the double bond differ in spatial orientation (cis: same side, trans: opposite sides).
Physical Properties and Trends:
Intermolecular Forces: Forces between molecules, including dispersion forces, dipole-dipole interactions, and hydrogen bonds, which influence physical properties such as melting point, boiling point, and solubility.
Dispersion Forces: Weak forces arising from temporary dipoles in molecules, present in all molecular substances but dominant in non-polar compounds.
Dipole-Dipole Interactions: Attractive forces between the positive and negative ends of polar molecules.
Hydrogen Bonds: Strong intermolecular forces between a hydrogen atom bonded to an electronegative atom (e.g., O, N, F) and another electronegative atom.
Homologous Series: A series of organic compounds with the same functional group, differing by a CH₂ unit, and showing trends in physical properties.
Melting Point and Boiling Point Trends: Determined by the strength of intermolecular forces; larger molecules with stronger forces have higher melting and boiling points.
Volatility: The tendency of a substance to vaporize, influenced by molecular size and intermolecular forces.
Solubility: The ability of a substance to dissolve in a solvent, influenced by the polarity of the compound and the solvent.
Functional Group Influence: Functional groups determine the polarity and hydrogen-bonding ability of a molecule, affecting physical properties like solubility and boiling point.
Organic Reactions and Reaction Pathways:
Saturated Compounds: Organic compounds with single bonds only (e.g., alkanes); they undergo substitution reactions.
Unsaturated Compounds: Organic compounds with double or triple bonds (e.g., alkenes, alkynes); they undergo addition reactions.
Substitution Reactions: A reaction in which an atom or group in a molecule is replaced by another atom or group (e.g., alkanes reacting with halogens).
Addition Reactions: Reactions in which atoms are added to a double or triple bond in an unsaturated molecule (e.g., alkenes reacting with H₂, Br₂, or HBr).
Oxidation Reactions of Alcohols:
Primary alcohols: Oxidize to aldehydes and further to carboxylic acids.
Secondary alcohols: Oxidize to ketones.
Tertiary alcohols: Resistant to oxidation.
Esterification: A reversible reaction between an alcohol and a carboxylic acid to form an ester and water, catalyzed by an acid.
Acid-Base Properties of Amines: Amines act as bases due to the lone pair of electrons on nitrogen and can react with acids to form amides.
Elimination Reactions: Reactions that remove atoms or groups from a molecule to form a double or triple bond (e.g., haloalkanes forming alkenes).
Reduction Reactions: Reactions that add hydrogen or remove oxygen from a molecule (e.g., nitriles reducing to amines).
Condensation Reactions: Reactions in which two molecules combine with the elimination of a small molecule like water (e.g., forming esters and amides).
Reaction Pathways: Sequences of chemical reactions used to synthesize a target molecule, involving reagents, conditions, and intermediate compounds.
Markovnikov’s Rule: In the addition of HX to an alkene, the hydrogen atom attaches to the carbon with the greater number of hydrogen atoms already bonded to it.
Properties and Structure of Organic Materials
Hydrocarbon Skeleton: The carbon chain or ring structure forming the backbone of organic molecules.
Functional Group: A specific group of atoms within a molecule responsible for its characteristic chemical reactions (e.g., -OH for alcohols, -COOH for carboxylic acids).
Structural Formula: A representation showing the arrangement of atoms and bonds in a molecule, either condensed or extended.
IUPAC Nomenclature: The systematic naming of organic compounds based on rules for identifying the parent chain, functional groups, and branching.
Structural Isomers: Compounds with the same molecular formula but different connectivity of atoms.
Stereoisomers: Compounds with the same structural formula but different spatial arrangements of atoms.
Geometrical Isomerism: A form of stereoisomerism in alkenes where groups attached to the double bond differ in spatial orientation (cis: same side, trans: opposite sides).
Physical Properties and Trends
Intermolecular Forces: Forces between molecules, including dispersion forces, dipole-dipole interactions, and hydrogen bonds, which influence physical properties such as melting point, boiling point, and solubility.
Dispersion Forces: Weak forces arising from temporary dipoles in molecules, present in all molecular substances but dominant in non-polar compounds.
Dipole-Dipole Interactions: Attractive forces between the positive and negative ends of polar molecules.
Hydrogen Bonds: Strong intermolecular forces between a hydrogen atom bonded to an electronegative atom (e.g., O, N, F) and another electronegative atom.
Homologous Series: A series of organic compounds with the same functional group, differing by a CH₂ unit, and showing trends in physical properties.
Melting Point and Boiling Point Trends: Determined by the strength of intermolecular forces; larger molecules with stronger forces have higher melting and boiling points.
Volatility: The tendency of a substance to vaporize, influenced by molecular size and intermolecular forces.
Solubility: The ability of a substance to dissolve in a solvent, influenced by the polarity of the compound and the solvent.
Functional Group Influence: Functional groups determine the polarity and hydrogen-bonding ability of a molecule, affecting physical properties like solubility and boiling point.
Organic Reactions and Reaction Pathways
Saturated Compounds: Organic compounds with single bonds only (e.g., alkanes); they undergo substitution reactions.
Unsaturated Compounds: Organic compounds with double or triple bonds (e.g., alkenes, alkynes); they undergo addition reactions.
Substitution Reactions: A reaction in which an atom or group in a molecule is replaced by another atom or group (e.g., alkanes reacting with halogens).
Addition Reactions: Reactions in which atoms are added to a double or triple bond in an unsaturated molecule (e.g., alkenes reacting with H₂, Br₂, or HBr).
Oxidation Reactions of Alcohols:
Primary alcohols: Oxidize to aldehydes and further to carboxylic acids.
Secondary alcohols: Oxidize to ketones.
Tertiary alcohols: Resistant to oxidation.
Esterification: A reversible reaction between an alcohol and a carboxylic acid to form an ester and water, catalyzed by an acid.
Acid-Base Properties of Amines: Amines act as bases due to the lone pair of electrons on nitrogen and can react with acids to form amides.
Elimination Reactions: Reactions that remove atoms or groups from a molecule to form a double or triple bond (e.g., haloalkanes forming alkenes).
Reduction Reactions: Reactions that add hydrogen or remove oxygen from a molecule (e.g., nitriles reducing to amines).
Condensation Reactions: Reactions in which two molecules combine with the elimination of a small molecule like water (e.g., forming esters and amides).
Reaction Pathways: Sequences of chemical reactions used to synthesize a target molecule, involving reagents, conditions, and intermediate compounds.
Markovnikov’s Rule: In the addition of HX to an alkene, the hydrogen atom attaches to the carbon with the greater number of hydrogen atoms already bonded to it.
Chemical Tests
Test for Alkanes and Alkenes:
Alkanes: No reaction with bromine water.
Alkenes: Decolorize bromine water due to addition reaction.
Test for Alcohols:
Primary alcohols: Oxidize to aldehydes/carboxylic acids.
Secondary alcohols: Oxidize to ketones.
Tertiary alcohols: Resistant to oxidation.
Test reagents: Acidified potassium dichromate (K2Cr2O7) or potassium permanganate (KMnO4).
Identification of Functional Groups:
Using characteristic reactions and physical observations to distinguish between classes of organic compounds.
Proteins and Carbohydrates
Primary Structure of Proteins: The sequence of amino acids in a polypeptide chain linked by peptide bonds.
Secondary Structure of Proteins: Includes α-helices and β-pleated sheets, formed by hydrogen bonding between the backbone of the polypeptide chain.
Tertiary Structure of Proteins: The three-dimensional shape of a protein, stabilized by interactions such as hydrogen bonds, ionic bonds, disulfide bridges, and hydrophobic interactions.
Quaternary Structure of Proteins: The arrangement of multiple polypeptide chains into a functional protein complex.
Enzymes: Biological catalysts that speed up chemical reactions by lowering the activation energy. Their activity depends on their specific three-dimensional structure.
Monosaccharides: The simplest form of carbohydrates with the empirical formula CH2O; they contain multiple hydroxyl groups and either an aldehyde (aldose) or ketone (ketose) group.
α-Glucose vs. β-Glucose: Isomers of glucose differing in the orientation of the hydroxyl group on the first carbon atom; α-glucose forms starch, while β-glucose forms cellulose.
Starch (Amylose and Amylopectin): Polysaccharides composed of α-glucose; amylose is linear, and amylopectin is branched.
Cellulose: A polysaccharide composed of β-glucose units, providing structural support in plant cell walls.
Triglycerides: Esters formed from glycerol and three fatty acid chains; their structure determines whether they are saturated or unsaturated.
Saponification: The base hydrolysis of triglycerides to produce glycerol and soap (salts of fatty acids).
Polymers
Polymers: Large molecules made by joining repeating units (monomers). Properties depend on structural features such as branching, molecular weight, and crystallinity.
LDPE vs. HDPE: Low-density polyethylene (LDPE) is highly branched and less dense, while high-density polyethylene (HDPE) is linear and more crystalline.
Polymer Tacticity: Arrangement of side groups in polypropene; isotactic, syndiotactic, and atactic polymers differ in their physical properties.
Polytetrafluoroethylene (PTFE): A polymer known for its high strength, low friction, and resistance to chemical reactions.
Analytical Techniques
Chromatography: A technique to separate and analyze components in a mixture, used for amino acids and proteins.
Electrophoresis: A method to separate molecules based on their size and charge using an electric field, often used for proteins.
Mass Spectrometry: Analytical technique used to determine the molecular weight and structure of a compound.
X-ray Crystallography: A method to determine the three-dimensional structure of molecules by analyzing the diffraction pattern of X-rays passing through a crystal.
Infrared (IR) Spectroscopy: Technique to identify functional groups in organic molecules by measuring vibrations of bonds in response to infrared radiation.
Unit 4 Topic 2: Chemical synthesis and design
Chemical Synthesis
Haber Process: Industrial synthesis of ammonia from nitrogen and hydrogen under specific conditions to optimize yield and rate.
Contact Process: Industrial production of sulfuric acid involving the oxidation of sulfur dioxide to sulfur trioxide.
Biodiesel Production: Transesterification of triglycerides using a base or lipase catalyst to produce fatty acid methyl esters (biodiesel).
Ethanol Production: Can be synthesized via fermentation of glucose or hydration of ethene.
Hydrogen Fuel Cell: A device converting chemical energy into electricity through redox reactions involving hydrogen and oxygen.
Atom Economy: A measure of the efficiency of a chemical reaction, calculated as the molecular weight of the desired product divided by the total molecular weight of reactants, multiplied by 100%.
Macromolecules: Polymers, Proteins, and Carbohydrates
Addition Polymers: Formed by the addition of monomers with double bonds (e.g., polyethene, polypropene).
Condensation Polymers: Formed by a reaction between monomers with the elimination of a small molecule (e.g., water).
Polypeptides: Chains of amino acids linked by peptide bonds, forming proteins.
Glycosidic Bonds: Bonds formed between monosaccharides during the formation of polysaccharides.
Biodegradability: The ability of a material to decompose by biological agents, influenced by its chemical structure.
Molecular Manufacturing
Molecular Manufacturing: The precise positioning of molecules to enable specific chemical reactions, used to synthesize advanced materials like carbon nanotubes and nanorobots.
