If you change the concentration of a product or reactant in a reaction, the EQUILIBRIUM constant will not change!
A good way to think of this is if I have 10 M of product over two M of reactant, my chemical equilibrium constant is equal to 5! If I decide to half the amount of product and reactant, it will still equal 5 as 5/1=5. Even if I just decreased the product, or the reactant, or increased one or the other, the reaction will favor either the forward or the reverse reaction and create more or less product or reactant to then balance the reaction once again in the forward and reverse directions, and you will get the same equilibrium constant as the ratio will simplify to be equivalent to any other reaction of those specific products and reactants are given the same conditions.
A chemical reaction at equilibrium represents a fixed ratio.
Le Chatlier's Principle
>Chemical reactions will adjust to minimize the effect of changes.
Without adding more reactants, you can encourage product formation by forcing the system out of equilibrium by removing the product as its made. If you do this, more product will need to be formed to reach equilibrium, thus you can form as much product as possible and use up the reactant you have!
A change in pressure DOES not impact the equilibrium constant.
However, a change in volume, which will impact pressure does change the equilibrium constant. If all P and R are gases, then here is a shortcut method:
If volume decreases, look to see which side has the greater number of moles. If it is the left side, the reaction will shift right, as more product will be made. If it is on the right side, the reaction will shift left as more reactants will be made.
Changing Temperature of the Reaction:
This does impact K!
If the reaction is exothermic, meaning that it releases heat to the environment, and therefore delta H or enthalpy is negative, bonds are being made. If you then heat this reaction, you will be inputting heat into a system that is trying to release heat. So, you will make the reaction favor the reverse reaction.
On the other hand, there are endothermic reactions, which require an INPUT of energy to break bonds! If you heat an endothermic reaction, then you will help the reaction form more product! And the reaction will shift right.
If you COOL a reaction, you are favoring the side that has a lower enthalpy!
If you HEAT a reaction, you are favoring the side with the higher enthalpy!
Response Of Chemical Equilibrium to Various Changes: [ENDORSED]
Moderators: Chem_Mod, Chem_Admin
-
- Posts: 23858
- Joined: Thu Aug 04, 2011 1:53 pm
- Has upvoted: 1253 times
Re: Response Of Chemical Equilibrium to Various Changes:
Postby Chem_Mod » Mon Jan 30, 2023 3:04 pm
Thanks
Return to “Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions”
Jump to
- NEWS
- NEWS & RESOURCES
- About The Forum
- Forum Rules and Helpful Hints
- How to make a New Post (submit a question) and use Equation Editor (click for details)
- Email Notification (click for details)
- How to Subscribe to a Forum, Subscribe to a Topic, and Bookmark a Topic (click for details)
- Endorsed Post (click for details)
- Multimedia Attachments (click for details)
- Strikethrough (click for details)
- Chem 14A
- Review of Chemical & Physical Principles
- SI Units, Unit Conversions
- Significant Figures
- Accuracy, Precision, Mole, Other Definitions
- Molarity, Solutions, Dilutions
- Empirical & Molecular Formulas
- Balancing Chemical Reactions
- Limiting Reactant Calculations
- The Quantum World
- Properties of Light
- Properties of Electrons
- Einstein Equation
- *Black Body Radiation
- Photoelectric Effect
- Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- DeBroglie Equation
- Heisenberg Indeterminacy (Uncertainty) Equation
- *Shrodinger Equation
- *Particle in a Box
- Wave Functions and s-, p-, d-, f- Orbitals
- Quantum Numbers and The H-Atom
- Electron Configurations for Multi-Electron Atoms
- Trends in The Periodic Table
- Chemical Bonds
- Ionic & Covalent Bonds
- Sigma & Pi Bonds
- Lewis Structures
- Resonance Structures
- Formal Charge and Oxidation Numbers
- Octet Exceptions
- Coordinate Covalent Bonds
- Polarisability of Anions, The Polarizing Power of Cations
- Electronegativity
- Dipole Moments
- Bond Lengths & Energies
- Forces and Liquid Structure
- Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
- Molecular Shape and Structure
- Determining Molecular Shape (VSEPR)
- Hybridization
- *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Coordination Compounds and their Biological Importance
- Naming
- Shape, Structure, Coordination Number, Ligands
- Biological Examples
- Industrial Examples
- *Stereochemistry
- *Crystal Field Theory
- *Molecular Orbital Theory Applied To Transition Metals
- Acids and Bases
- Properties & Structures of Inorganic & Organic Acids
- Properties & Structures of Inorganic & Organic Bases
- Amphoteric Compounds
- Lewis Acids & Bases
- Bronsted Acids & Bases
- Conjugate Acids & Bases
- Acidity & Basicity Constants and The Conjugate Seesaw
- Calculating pH or pOH for Strong & Weak Acids & Bases
- Polyprotic Acids & Bases
- Identifying Acidic & Basic Salts
- Calculating the pH of Salt Solutions
- Air Pollution & Acid Rain
- Chem 14A Uploaded Files (Worksheets, etc.)
- Student Social/Study Group
- Administrative Questions and Class Announcements
- General Science Questions
- *Aqueous Equilibria
- *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
- *Biological Importance of Buffer Solutions
- *Titrations & Titration Calculations
- *Indicators
- Chem 14B
- Chemical Equilibrium
- Ideal Gases
- Equilibrium Constants & Calculating Concentrations
- Non-Equilibrium Conditions & The Reaction Quotient
- Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Thermochemistry
- Phase Changes & Related Calculations
- Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Heat Capacities, Calorimeters & Calorimetry Calculations
- Thermodynamics
- Thermodynamic Systems (Open, Closed, Isolated)
- Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Calculating Work of Expansion
- Concepts & Calculations Using First Law of Thermodynamics
- Concepts & Calculations Using Second Law of Thermodynamics
- Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Entropy Changes Due to Changes in Volume and Temperature
- Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Gibbs Free Energy Concepts and Calculations
- Van't Hoff Equation
- Environment, Fossil Fuels, Alternative Fuels
- Biological Examples (*DNA Structural Transitions, etc.)
- Electrochemistry
- Balancing Redox Reactions
- Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Work, Gibbs Free Energy, Cell (Redox) Potentials
- Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Chemical Kinetics
- Kinetics vs. Thermodynamics Controlling a Reaction
- General Rate Laws
- Method of Initial Rates (To Determine n and k)
- Zero Order Reactions
- First Order Reactions
- Second Order Reactions
- Reaction Mechanisms, Reaction Profiles
- Arrhenius Equation, Activation Energies, Catalysts
- *Enzyme Kinetics
- Experimental Details
- Environment, Ozone, CFCs
- Biological Examples
- Chem 14B Uploaded Files (Worksheets, etc.)
- Student Social/Study Group
- Administrative Questions and Class Announcements
- General Science Questions
- *Thermodynamics and Kinetics of Organic Reactions
- *Electrophiles
- *Nucleophiles
- *Organic Reaction Mechanisms in General
- *Electrophilic Addition
- *Nucleophilic Substitution
- *Free Energy of Activation vs Activation Energy
- *Complex Reaction Coordinate Diagrams
- *Names and Structures of Organic Molecules
- *Alkanes
- *Cycloalkanes
- *Alkenes
- *Cycloalkenes
- *Alkynes
- *Constitutional and Geometric Isomers (cis, Z and trans, E)
- *Haloalkanes
- *Haloalkenes
- *Alcohols
- *Ethers
- *Aldehydes
- *Ketones
- *Carboxylic Acids
- *Amines
- *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
- *Conformations of Organic Molecules
- *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
- *Cyclopropanes and Cyclobutanes
- *Cyclopentanes
- *Cyclohexanes (Chair, Boat, Geometric Isomers)
- *Calculations Using ΔG° = -RT ln K
- *ChemDraw
- *Chem3D
- Chem 14C/D Topics
- Resonance in Organic Compounds
- Stereochemistry in Organic Compounds (Chirality, Stereoisomers, R/S, d/l, Fischer Projections)
Who is online
Users browsing this forum: No registered users and 10 guests