Chemical equilibrium Definition and 78 Threads

In a chemical reaction, chemical equilibrium is the state in which both the reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system. This state results when the forward reaction proceeds at the same rate as the reverse reaction. The reaction rates of the forward and backward reactions are generally not zero, but they are equal. Thus, there are no net changes in the concentrations of the reactants and products. Such a state is known as dynamic equilibrium.

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  1. Z

    Chemistry A calculation of equilibrium constant of a reaction of phosgene

    We start with ##n_i## moles of phosgene and zero of the products. The initial total pressure and also partial pressure of phosgene is ##\frac{n_iRT}{V}##. At equilibrium, suppose ##x## moles of phosgene have reacted. Then we have ##n_i-x## moles of phosgene left and ##x## mole of each of the...
  2. E

    I Equilibrium constant change with stoichiometric doubling (Callen)?

    Callen asks us (with respect to an ideal gas) I had thought to proceed as follow. We have the definition for the singular reaction: $$\ln K_s(T) = - \sum_j \nu_j \phi_j(T).$$ Now a reaction which is the sum of this reaction with itself (doubled reaction) has ##\nu_j \to 2\nu_j## so that its...
  3. E

    Thermodynamic equilibrium for systems only open to particle exchange

    I am only interested in the initial equilibrium conditions, and I am struggling to convince myself whether that should correspond to the equality of chemical potentials for H2 or an equality of temperatures as well. My work is as below: We take both gases as simple ideal (this is only relevant...
  4. samy4408

    A question about chemical equilibrium

    Hello we learned about the chemical equilibrium and how to write it's formula in the case of liquid and gaseous phase , what about a reaction involving different phases ? like this one : how do we write the formula for the chemical equilibrium ? do we just ignore the carbon ,is there any rules...
  5. samy4408

    Chemistry An exercise about chemical equilibrium

    Hello i am trying to solve a problem set about chemical equilibrium , the issue is that my results don't correspond to the correction . can someone tell me what is wrong with my answer , thanks here is the problem and his correction : here is my answer :
  6. samy4408

    Chemistry Confused by an exercise on the subject of chemical equilibrium

    Hello , i am a little confused about this exercise because we talk about gases reaction and we are asked about the concentrations P.S : i have other questions that depends on your answer . Thanks .
  7. Huzaifa

    Chemistry Effect of temperature change in Le Chatelier's Principle

    The effect of temperature change in Le Chatelier's Principle is given by the equation $$ \log \left(\frac{\mathrm{K}_{2}}{\mathrm{~K}_{1}}\right)=\frac{\Delta \mathrm{H}}{2.303 \mathrm{R}}\left[\frac{1}{\mathrm{~T}_{1}}-\frac{1}{\mathrm{~T}_{2}}\right] $$. How to derive $$ \log...
  8. D

    Chemistry Chemical Equilibrium: find concentration from 2 solutions (ICE table)

    Hello! I've recently encountered this problem https://www.physicsforums.com/threads/need-major-help.117630/ and solved it and I'm stuck at choosing between 2 solutions. I don't understand why do we need to plug in 0.39 and 0.65 to (1-2x) and NOT to (1-2x)^2. I mean, we were given 2NO2, not just...
  9. SilverSoldier

    Approximations in Chemical Equilibrium (add a weak acid HA into pure water)

    Suppose we add a weak acid HA into pure water, so that upon addition its initial concentration is c. The following equilibria should establish in the system. $$\text{HA}+\text{H}_2\text{O}\rightleftharpoons\text{H}_3\text{O}^++\text{A}^-$$...
  10. B

    Solving Chemical Equilibrium Concentrations Within a Rocket Nozzle

    I would like to write a program to calculate the equilibrium concentrations of 10 or more chemical species at any axial location along a quasi 1D isentropic methane-liquid oxygen rocket nozzle. Is anyone aware of any good textbooks that cover this topic in depth, specifically dealing with large...
  11. r12214001

    Chemistry Relationship between chemical equilibrium and rate equilibrium

    Q: Is it true that the value of K depends on the amounts of reactants and products mixed together initially? Explain. A:NO, Equilibrium and rates of reaction (kinetics) are independent of each other. A reaction with a large equilibrium constant value may be a fast reaction or a slow reaction...
  12. navneet9431

    Why doesn't the amount of Cl increase?

    Homework Statement Homework Equations Formula of Kp and Kc The Attempt at a Solution You will easily be able to identify that the reaction will proceed in the forward direction when some inert gas is introduced. So,my question is that why won't the amount of chlorine formed increase in...
  13. S

    How Does Increased Pressure Affect Chemical Equilibrium in the Reaction A⇔2B?

    Homework Statement Consider the reaction : A⇔2B (⇔ stands for reversible). 1 mol of A and 2 mol of B are taken in a closed container at equilibrium. Suppose the pressure is increased, how much of B (by moles) will decompose to restore equilibrium ? Homework EquationsThe Attempt at a Solution...
  14. curiosity colour

    Chemical Equilibrium Q: How Does Solution (a) Know PH2S=Ammonia?

    I have a question about the solution (a) in this example, how does it know PH2S is the same as ammonia? is there something I've miss?
  15. D

    I Gibbs Energy and chemical equilibrium

    Hi, i'll apologize for my english in advance, so here's the question. I was wondering about the equilibrium condition for a chemical reaction. We know that a closed system is in equilibrium if the Gibbs free energy's function has a minimun in that point. So, taking Temperature and Pressure as...
  16. Aafia

    Is 8.3 or 11.7 the Correct Equilibrium Constant?

    Homework Statement [/B] The following reaction was allowed to reach the state of equilibrium 2A+B <====> C The initial amounts of reactant present in one litre of solution were 0.5 mole of A and 0.6 mole of B. At equilibrium the amounts were 0.2 mole of A and 0.45 mole of B and 0.15 mole of...
  17. V

    A Question about Chemical Equilibrium

    say we have a reaction: N2O4 <====> 2NO2 for this reaction,if initial number of moles of N2O4 is 'a' can we write t = 0 a - at equilbrium a-x...
  18. Nader AbdlGhani

    The unit of measurement of degree of dissociation ( α ) ?

    What's the unit used to measure α ? if α=(Kd/C)0.5 where Kd is the dissociation constant and C is the total concentration of electrolyte .
  19. Karan Punjabi

    Effect of Temperature on Chemical Equilibrium

    Guys, I'm studying about Le-chatelier's principle and the topic is effect of temperature. I just went through it and found a difficulty that why K values changes i.e why the equilibrium constant changes as in other effects like changes in concentration, pressure,etc the K values remains constant.
  20. 24forChromium

    Possibility and detection of this chemical equilibrium

    Dissolve a salt containingCr2O72- and an "inert cation" in water, would the following equilibrium occur in appreciable quantity? Cr2O72-+OH-⇔2CrO42-+H+ If it does occur, I suppose the acidity of the water would affect the equilibrium constant (or at least the relative concentration of the...
  21. R

    Coal Gasifier - Thermodynamics Question

    Homework Statement The problem is in the attached picture. I simply do not know what an "equilibrium equation" is and what it means by the composition. My professor is unbelievably difficult to get a straight, understandable answer from. I've already taken thermodynamics, but we did not learn...
  22. Titan97

    Why is k4 Greater than k3 in Cadmium Complex Formation?

    Homework Statement The formation of cadmium complexes with Br- exhibits successive equilibrium constants such that log(k1)=1.56, log(k2)=0.54, log(k3)=0.05, log(k4)=0.37. Explain why k4 is greater than k3 Homework Equations $$K=e^{\frac{-\Delta H}{RT}}\cdot e^{\frac{\Delta S}{R}}$$ The...
  23. K

    Kinetic equilibrum and chemical equilibrium

    All particle species are in equilibrium at early times of the universe. But I didn't find any book that makes the difference of kinetic and chemical equilibrium clear. I have some of my own opinions and I hope to get your comments: (1) kinetic equilibrium means the distribution function obeys...
  24. E

    Chemical equilibrium for simultaneous dissociation reactions

    Hello everyone, Sorry I didn't have the time to rewrite the question, Can you help me with this?
  25. MexChemE

    Equilibrium of ammonia synthesis

    Homework Statement In order to obtain commercial conversion levels in the production of ammonia, reactors operate between a pressure range from 150 to 300 atm, and a temperature range from 700 to 750 K. Calculate the mole fraction of N2 when the reaction reaches equilibrium at 300 atm and 723...
  26. K

    Chemical Equilibrium and Le Chatelier's Principle

    Homework Statement Without adding any Chromium based compounds, how would you manipulate the above equation to produce more CrO42- ions? Be sure to use chemical equations to show the answer. Homework Equations 2CrO42- (aq) + 2H3O+ <--> Cr2O72-(aq) + 3H2O (l) The Attempt at a Solution So my...
  27. WannabeNewton

    Surfactant adsorption chemical equilibrium

    Homework Statement A dilute solution of surfactants can be regarded as an ideal three-dimensional gas. As surfactant molecules can reduce their energy by contact with air, a fraction of them migrate to the surface where they can be treated as a two-dimensional ideal gas. Surfactants are...
  28. Entanglement

    Equilibrium Constant: H2+O2->H2O

    H2+1/2 O2 ---------> H20 If the equation is multiplied by 2 Will the equilibrium constant change or remain constant ?
  29. M

    Chemical Equilibrium of Reaction's constant?

    I'm currently studying for a test and I'm having problem with this concept: If I have 3 different Equilibrium constants for different reactions like Kc=103, Kc=1 and KC=10-4, which one's forward reaction is most favorable, and which one's reverse reaction is most favorable? Maybe it's the...
  30. marellasunny

    Chemical equilibrium reaction for burned gases in engine

    I do not understand how equation(3) occurs.(taken from the book Internal Combustion Engines by John B.Heywood) $$ $$ Consider a reactive mixture of ideal gases. The reactant species M_a,M_b etc.and the product species M_l,M_m etc. are related by the general reaction whose stoichiometry is...
  31. T

    How Does Removing Ammonia Affect Chemical Equilibrium?

    Hi, I have simple question N2+3H2 = 2NH3 + heat How would the equilibrium position be affected if ammonia is removed from the vessel?, shouldn't it move to the left to produce more reactants and replace the ammonia? why does it move to the right?, because that's what my texbook says.
  32. Telemachus

    Chemical equilibrium, getting molarity given pH and Kb

    What should be the molarity in an aquatic dissolution for Trimethylamine, ##(CH_3)_3N## if ##pH=11,2##? ##(CH_3)_3N+H_2O \rightleftharpoons (CH_3)_3NH^++OH^-##, ##K_b=6.3 \times 10^{-5}## I know that ##pH+pOH=14 \rightarrow pOH=2.8##, then ##[OH^-]=1.58 \times 10^{-3}## And...
  33. K

    Chemical Equilibrium with Multiple Kc

    Homework Statement Compound A can react to form B and C according to the following A<->2B Kc=1 A<->C Kc=1 If 1 mole of A is solved into 1 litre of water, what will the concentration of A be after equilibrium has been reached?Homework Equations ICE-tables(?) A<->2B+C Kc=([B]^2[C])/[A] The...
  34. W

    Halved volume with chemical equilibrium

    Homework Statement The reaction is PCl5 (g) <=> PCl3 (g) + Cl2 In an unknow volume, the following mixture is balanced: 0.14 atm of PCl5 0.36 atm of PCl3 0.50 atm of Cl2 What would be the the pressure of the whole mixture if the volume would be halved? (the answer is 1.88 atm) Homework...
  35. O

    Chemistry Calculate Reactant Concentration from Chemical Equilibrium Moles

    If someone could check my work on this, I'd appreciate it: Thanks!
  36. I

    Chemical Equilibrium: Understanding & Equation

    Can someone help me understand the concept of chemcial equilbrium. I think I understand in a certain chemical reaction, know matter the amount of reactants or products, the equilibrium constant will remain approximatly the same. I don't fully understand how the equation to solve for the...
  37. B

    Effect of Temperature on Chemical Equilibrium

    Hi guys I am a student of AP Chemistry. I am trying to understand the effect of temperature on equilibrium. I know that under the change of temperature, the equilibrium will shift to favor the endothermic process if heat is added and vice versa. But employing the Arrhenius Equation, I see a...
  38. H

    Methane Combustion and Chemical Equilibrium

    This may belong in the Chemistry section but this is a problem from my Thermodynamics class, so I'll post it here and then move to the Chem section if need be. Homework Statement Methane (CH4) is the principal constituent of natural gas and is often used to represent natural gas. Consider...
  39. R

    Calculation of enthelpy and internal energy or air in chemical equilibrium

    Homework Statement Consider air in chemical equilibrium at 0.1 atm and T=4500 K. The chemical species are O2, O, N2, N (Ignore NO). Calculate the enthalpy and internal energy per unit mass of the mixture. Neglect electronic excitation in your calculations. K_{p,O_2}=12.19 atm...
  40. P

    Chemical Equilibrium and Concentration

    The reaction between hydrogen and fluorine has an equilibrium constant of 1.15x102 at a certain temperature. Given the reaction equation H2(g) + F2(g) -> 2HF(g), calculate the equilibrium concentration of HF after 3.00 mol of each component is added to a 1.500 L flask. I attempted solving it...
  41. C

    How does a reaction return to equilibrium?

    Hey guys, I have a question regarding the process by which a reaction returns to equilibrium. If a reaction's reaction quotient is greater than its equilibrium constant, it will shift towards the reactants side of the equation to return to equilibrium. How exactly does this happen? Does...
  42. F

    Chemical Equilibrium and Probability

    I am looking at this equilibrium: H2O + D2O <-> 2DHO (D = Deuterium) I have 2.0 mol of H2O, 1.0 mol of D2O and 2.0 mol of DHO. What are the equilibrium amounts of each of the molecules? What I tried: 6 mol of H, 4 mol of D H2O: P(X=H) & P(Y=H) = 9/25 D2O: P(X=D) & P(Y=D) = 4/25 HDO...
  43. H

    Chemical Equilibrium Constant Calculation

    Homework Statement If Q = 1.0 1042 for the reaction C(s) + O2(g) → CO2(g) at 25°C, calculate Keq. dGof (Kj/mol) of... C(s)=0 O2(g)=0 CO2(g)=-394.36 Homework Equations dGorxn = -R*T*ln(K)The Attempt at a Solution -394.36*1000 = -8.314472(298)ln(K) K=1.3e69 This is the wrong answer. I'm...
  44. C

    Chemical equilibrium concentrations

    I have a problem in which It asks to find the equilibrium concentrations but it only give the value of the equilibrium constant and the chemical equation. Is this even possible to solve or does it not have enough information? Here is the problem Determine the equilibrium concentrations...
  45. Z

    How Is the Equilibrium Constant Calculated for I2 and I- in KI Solution?

    Homework Statement A saturated solution of iodine in water contains 0.330g of I2/L. More than this can dissolve in a KI solution because of the following equilibrium- I2(aq) +I-(aq) ------> I3- (aq) where 2 and 3 are subscripts and - is negative charge A 0.1M KI solution actually...
  46. Z

    How Do You Calculate CO Concentration at Equilibrium in a Gaseous Reaction?

    Homework Statement At a certain temperature, the equilibrium constant for the gaseous reaction of CO with O2 to produce CO2 is 5000 lit/mole. Calculate [CO] at equilibrium, if 1 mol each of CO and O2 afre placed in a 2 L vessel and allowed to come to equilibrium. Homework Equations...
  47. Z

    Concentration of solids and liquids in Chemical Equilibrium

    Homework Statement Why don't we take into consideration the concentration of pure solids and pure liquids in equilibrium constant expression? I read that their concentration per unit volume does not change. If the concentrations (moles per litre) don't change then it won't undergo any...
  48. I

    How Does Le Chatelier's Principle Explain a Soft Drink Going Flat?

    Homework Statement 1) Use Le Chatelier's prinicile to explain how a shift in the equilibrium H2CO3(aq) ⇌ H2O(l) + CO2(g) causes a soft drink to go flat when its container is left open to the atmosphere. 2) How might the addition of a noble gas to the reaction vessel affect this equilibrium...
  49. Sirsh

    Explaining How Temperature Change Affects Chemical Equilibrium

    Hey all the people reading this, Just wondering if anyone can explain how a equilibrium system changes with a increase/decrease in temperature occurs. I've been taught that: If my reaction is exothermic i.e. reactants -> products + energy; and i am going to decrease temperature it would be...
  50. A

    I with chemical equilibrium problems

    [b]1. okay so the equation is: 3A+2B---->C+D K=1.00x10(to the negative third power) A=9.5-M C=0.0200-M D=0.0200 what is B ? [b]3. the answer is either 1.24: 0.0216: : 0.00180 : or 0.110 (i don't remember) so what i don't get is HOW DO I SET UP THE PROBLEM? :confused: go step...
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