K from Initial Amounts and One Known Equilibrium Amount. We have grown leaps and bounds to be the best Online Tuition Website in India with immensely talented Vedantu Master Teachers, from the most reputed institutions. The concentration cannot be negative; hence we discard x = 1.78. The reaction may be said to be "complete" or "quantitative.". We can write the equilibrium Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. Use this information to derive terms for the equilibrium concentrations of the reactants, presenting all the information in an ICE table. These balanced chemical reactions form the basis for the concept of equilibrium concentration. All of this is divided by, we think about our reactants next, and they both have coefficients of one in the balanced equation. Theyll have different numerical values, but they still express the same reactions equilibrium. aA +bB cC + dD. Now we figured out that the equilibrium lies to the right, so therefore the equilibrium lies to the side that has the acid with the higher pKa value. 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So the mole ratio of bromine Here we have our equilibrium concentrations plugged into our equilibrium constant expression, and also Kc was equal to 7.0 for this reaction at 400 Kelvin so 7.0 is plugged in . The ICE table may now be updated with numerical values for all its concentrations: Finally, substitute the equilibrium concentrations into the K expression and solve: When 1 mol each of C2H5OH and CH3CO2H are allowed to react in 1 L of the solvent dioxane, equilibrium is established when 1313 mol of each of the reactants remains. The Kp calculator is a tool that will convert the equilibrium constant, Kc, to Kp - the equilibrium constant in terms of partial pressure. - [Instructor] An equilibrium For these calculations, a four-step approach is typically useful: The last two example exercises of this chapter demonstrate the application of this strategy. gain some of our products. The x's represent essentially the change in concentration for the reactants and products. How do I determine the equilibrium concentration given Kc and the Calculating_Equilibrium_Constants - Purdue University What is this brick with a round back and a stud on the side used for? This equation provides all the information you will need to calculate the equilibrium concentrations of all the species with the given equilibrium constant Keq. And once again, the coefficient is a one. Also, note the coefficient for the silver ion becomes an exponent in . Solution. Gen. Chem II Chapter 17 Flashcards | Quizlet E stands for equilibrium concentration. The $\ce{[FeSCN^2+]_\text{equil}}=\pu{6.39e5 M}.$, $$\ce{[Fe^3+]_\text{equil}} = \ce{[Fe^3+]_\text{initial}} - \ce{[FeSCN^2+]_\text{equil}} $$, $$ = \pu{1.00e-3 M} - \pu{6.39e5 M} = \pu{0.94e-3 M}$$, $$\ce{[SCN-]_\text{equil}} = \ce{[SCN-]_\text{initial}} - \ce{[FeSCN^2+]_\text{equil}} $$, $$ =\pu{0.400e-3 M} - \pu{6.39e5 M} = \pu{0.336e-3 M}$$. Also besides that you should then correct in the denominator for concentratioms Fe3+ and SCN- that have reacted by substracting with concentration of formed FeSCN2. $$\ce{Fe^3+_{(aq)} + SCN^-_{(aq)} <=> FeSCN^2+_{(aq)}}$$. Lancaster holds a Doctor of Philosophy in chemistry from the University of Washington. So from only 2.20 volts, we get a huge number for the equilibrium constant. this particular reaction. She has taught science courses at the high school, college, and graduate levels. [OH]=[NH4+]=0.0021M;[OH]=[NH4+]=0.0021M; [NH3] = 0.25 M. As an Amazon Associate we earn from qualifying purchases. competitive exams, Heartfelt and insightful conversations In this video, we'll learn how to use initial concentrations along with the equilibrium constant to calculate the concentrations of reaction species at equilibrium. Where does the version of Hamapil that is different from the Gemara come from? Helmenstine, Anne Marie, Ph.D. (2023, April 5). This type of reaction is considered to be reversible. Creative Commons Attribution License So it would be the partial Substitution into the expression for Kc (to check the calculation) gives. We recommend using a Just in case you are not sure, the subscripted zero, as in [H 2] o, means the initial concentration. Determine the direction the reaction proceeds. How do you calculate the equilibrium constant with the absorbance of a Next, we think about Br2 For the example, the [H2] = 1.6 --x, [I2] = 2.4 --x and [HI] = 2x. It can be understood from the graph above, that initially, the concentration of the product is zero. initial partial pressure of that would be zero. both of our products, it must be minus X for The steps are as below. Still, with time, the concentration of the product increases and the concentration of the reactant decreases as it is getting consumed. be the same calculation, 0.60 minus x would be 0.60 minus 0.34, so the equilibrium Calculation of equilibrium constant given the reaction temperature of our reactant, N2O4. So that's the partial pressure The Keq = 0.04 for the reaction. And let's say we do an experiment and we allow this reaction The basic strategy of this computation is helpful for many types of equilibrium computations and relies on the use of terms for the reactant and product concentrations initially present, for how they change as the reaction proceeds, and for what they are when the system reaches equilibrium. Kconly changes if the temperature at which the reaction occurs changes. For the example, multiply the right-hand side of the equation to yield 3.84 -- 4x + x^2. Parabolic, suborbital and ballistic trajectories all follow elliptic paths. Taking the square root of both sides gives us 2.65 is equal to need to look at mole ratios. Calculating the Equilibrium Constant | Boundless Chemistry - Course Hero Write the generic expression for the Keq for the reaction. These values are substitued into the equilibrium expression and the value All of the products and reactants are in the same phase for a reaction at homogeneous equilibrium. K. the equilibrium concentrations or pressures of each species that occurs What is the equilibrium constant for the reaction of NH3 with water? But only 0.34 works since 2.46 would create negative molarities for the reactants at equilibrium. https://www.thoughtco.com/equilibrium-constant-606794 (accessed May 2, 2023). And for our products, we would have the partial We say that equilibrium has been reached when the reverse and forward reactions are proceeding at the same rate. with super achievers, Know more about our passion to So as the net reaction moved to the right, we lost some of our reactants and we gained some of our products until the reaction reached equilibrium and we got our equilibrium Equilibrium Constant (Kc, Kp) - Definition, Applications, Formula - BYJU'S The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo Rearrange to generate the quadratic equation format, which is .84x^2 -- 4x + 3.84 = 0. 100+ Video Tutorials, Flashcards and Weekly Seminars. Changes in the concentrations of chemicals will shift chemical equilibrium according to Le Chateliers Principle as such: When the concentration of a reactant is increased, the chemical equilibrium will shift towards the products. two x over 0.60 minus x. For chlorine, it would So 0.68 molar is the equilibrium What are the equilibrium concentrations for a mixture that is initially 0.15 M in CH3CO2H, 0.15 M in C2H5OH, 0.40 M in CH3CO2C2H5, and 0.40 M in H2O? 0.019. Next, we plug in our For this equation, the equilibrium constant is defined as: \[K_{c}\] = \[\frac{[c]^{c} [D]^{d}}{[A]^{a} [B]^{b}}\]. the balanced equation to write an equilibrium What is the equilibrium constant for the weak acid KHP? state turns into 2NO2 also in the gaseous state. The constant, Keq, defines for equilibrium of the chemical reaction. concentration for BrCl. equilibrium partial pressures for carbon dioxide and the equilibrium constant expression are equilibrium concentrations, Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. Next, we think about mole ratios. The equilibrium constant is the value of the reaction quotient that is calculated from the expression for chemical equilibrium. The last step is to solve the quadratic equation to find the value of x. i.e., r f = r b Or, kf [A]a[B]b = kb [C]c [D]d. For the following chemical reaction:aA(g) + bB(g) cC(g) + dD(g). Calculate the Equilibrium Constant for the reaction with respect to. Therefore, we get the following equilibrium concentration. x = - 0.038 and x = The third step is to form the ICE table and identify what quantities are given and what all needs to be found. Why refined oil is cheaper than cold press oil? So the equilibrium favors the weaker acid. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License . I did not square the problem like he did and used the quadratic formula to solve. equilibrium concentration must be 0.60 minus x. So for both of our reactants, we have ones as coefficients I'm following the outline from the comment by user21398. N2O4 raised to the first power. And if you write it this First, we'll find, For the last question when finding the Kp I got .28 instead of .11 when I plugged (.2)(3.4)/(3.9)(1.6). We start by writing the Step 2: Click "Calculate Equilibrium Constant" to get the results. The balanced equation for the decomposition of PCl5 is. So from this, I assumed that the concentrations of $\ce{SCN-}$ and $\ce{Fe^{3+}}$ are both $0.002\ \mathrm{M}$. then you must include on every physical page the following attribution: If you are redistributing all or part of this book in a digital format, To log in and use all the features of Khan Academy, please enable JavaScript in your browser. Helmenstine, Anne Marie, Ph.D. "Equilibrium Constant Kc and How to Calculate It." 15.7: Finding Equilibrium Concentrations - Chemistry LibreTexts Write the balanced chemical equation for the reaction. The acronym ICE is commonly used to refer to this mathematical approach, and the concentrations terms are usually gathered in a tabular format called an ICE table. To use the equilibrium constant calculator, follow these steps: Step 1: Enter the reactants, products, and their concentrations in the input fields. When the chemical is in equilibrium, the ratio of the products to the reactants is called the equilibrium constant. The equilibrium constant for this reaction with dioxane as a solvent is 4.0. So Kp is equal to, we think Direct link to Maisha Ahmed Mithi's post Q. Substituting the equilibrium concentrations into the equilibrium constant equation gives. rev2023.5.1.43405. For different reactions, those rates will become equal at various places in the transformation of reactant into a product. And we can figure out Thanks for contributing an answer to Chemistry Stack Exchange! we first need to write the equilibrium constant expression. together, we lose our reactants, and that means we're gonna We say that a chemical is in an equilibrium concentration when the products and reactants do not change as time moves on. Folder's list view has different sized fonts in different folders. If the value for Kc is very large, then the equilibrium favors the reaction to the right, and there are more products than reactants. Knowledge of the quantitative aspects of these equilibria is required to compute a dosage amount that will solicit the desired therapeutic effect. [H2O] = 0.0046 M, Calculating If the concentrations are not in moles per liter, you need to convert them to the appropriate units before calculating Kc. it's a one to one mole ratio of bromine to chlorine. Rearrange by algebra to yield Keq * (2x)^2 = (1.6 -- x) * (2.4 -- x). Amount, Calculating K from Known Initial Amounts and the Known Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? This is the Keq quoted at the start of the problem. The expression for Keq is the products over the reactants. Can corresponding author withdraw a paper after it has accepted without permission/acceptance of first author, "Signpost" puzzle from Tatham's collection. The final starting information is that the [HI] = 0.0M. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Usually, only two phases are present, such as liquids and gases or solids and liquids. The units for Kc will then need to be adjusted accordingly. Now that you know how to calculate equilibrium concentration lets look at some solved problems for better understanding. Using the dilution law, I get the following concentrations: $$\ce{[Fe^3+]_\text{initial}} = \pu{2.00 mM} \cdot \frac{\pu{5 mL}}{\pu{10 mL}} = \pu{1.00 mM}$$, $$\ce{[SCN-]_\text{initial}} = \pu{2.00 mM} \cdot \frac{\pu{2 mL}}{\pu{10 mL}} = \pu{0.400 mM}$$, The equilibrium concentration of the complex is already calculated, $\ce{[FeSCN^2+]_\text{equil}}=\pu{6.39e5 M}.$. How to use the likert scale in statistical How to convert serrapeptase international How to substitute citric acid for tartaric How to calculate marginal return on an investment, Saskatchewan Schools; Equilibrium Constant Expression. For BrCl, it's two times x If the value for the equilibrium constant is small, then the equilibrium favors the reaction to the left, and there are more reactants than products. So H2O has increased in partial pressure. revolutionise online education, Check out the roles we're currently The equilibrium constant and table will be very beneficial when we look at how to calculate equilibrium concentration. concentration of chlorine is also 0.26 molar. And since there is a coefficient If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. If the value of Kc approaches zero, the reaction may be considered not to occur. Connect with a tutor from a university of your choice in minutes. Want to cite, share, or modify this book? So the initial partial pressure What Is a Second Order Reaction in Chemistry? measured partial pressures are 4.10 atmospheres for carbon dioxide, 1.80 atmospheres for hydrogen gas and 3.20 atmospheres for H2O. Step 1: Determine the stoichiometric coefficients a, b, c, and d from the balanced equation aA(g)+bB(g) cC(g)+dD(g) a A ( g) + b B ( g) c C ( g . So if we gained plus 0.20 for H2O, we're also gonna gain plus Step1: Write the balanced equation for the reaction for which the concentration is to be calculated. An explanation to working out the concentration of substances at equilibrium. equilibrium concentrations. ThoughtCo, Apr. Except where otherwise noted, textbooks on this site In a chemical reaction, when both the reactants and the products are in a concentration which does not change with time any more, it is said to be in a state of chemical equilibrium. Posted 2 years ago. Calculating Concentration at Equilibrium - YouTube that Kc is equal to 0.211, and this is at 100 degrees Celsius. Is there such a thing as "right to be heard" by the authorities? I found the concentration of $\ce{FeSCN^2+_{(aq)}}$ to be $\pu{6.39e-5 M}$ using this equation: $$\mathrm{Absorbance} = \mathrm{slope}\cdot \mathrm{conc. The first step is to write down the balanced equation of the chemical reaction. and you must attribute OpenStax. At equilibrium the concentration of I 2 is 6.61 10 4 M so that. Worked example: Calculating equilibrium concentrations from initial For the example, the [H2] = 1.6 --x, [I2] = 2.4 --x and [HI] = 2x. This book uses the Now that we know that change 2023 Leaf Group Ltd. / Leaf Group Media, All Rights Reserved. So we need to write an In the balanced equation, Substitute the concentration expressions into the formula for Keq. So they have the opportunity of having both a Kc (using molarity) and a Kp (using pressure units). \[K_{c}\] = \[\frac{[C_{2} H_{6}]}{[C_{2}H_{4}][H_{2}]}\], 0.98 = \[\frac{x}{x^{2} - 0.86x\: +\: 0.1749}\]. Using this value, I used the equation for the K constant of an equilibrium: $$\mathrm{K} = \frac{[\ce{FeSCN^2+}]}{[\ce{Fe^3+}][\ce{SCN^-}]}$$, $$\mathrm{K} = \frac{\pu{6.39e-5}}{0.002^2}$$. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Enquire now. 2.4 = ( (1.2 + x) (1.2 + x)) / 2 (because now litres is doubled) Your ICE table is about amounts, and the equilibrium concentration is about concentrations. Learn more about Stack Overflow the company, and our products. [CO] = 0.0046 M When the concentration of a product increases, the chemical equilibrium will shift towards the reactants. The changes in the other species must The equilibrium constant is a dimensionless quantity (has no units). Calculating an Equilibrium Constant Using Partial Pressures Which is why you get 0.28 instead of the actual answer of 0.11. didn't yall say if we have gas we use pressure to get like kp so how come we have gas and we get the concentration and you solve to get kc, For gases we can express their concentration in molarity as well as pressure units like pascals or bars. At equilibrium the concentration of I2 is 6.61 104 M so that. the Pandemic, Highly-interactive classroom that makes How are engines numbered on Starship and Super Heavy? For example, assume the initial [H2] is 1.6M and [I2] is 2.4M. $\begingroup$ You get the equilibrium constant by dividing the concentrations on the right side with the concentrations on the left side. How to Calculate Kc From Concentrations | Chemistry | Study.com Using the Keq and the initial concentrations, the concentration of both the products and reactants are determined at the equilibrium point. Step 2: Convert the given concentrations into Molarity. So x is equal to 1.59 divided by 4.65, which is equal to 0.34. dioxide reacts with hydrogen gas to produce carbon monoxide and H2O. so we're gonna write minus x under bromine in our ICE table. Assume the generic reaction is aA + bB <--> cC + dD. 1. Dec 15, 2022 OpenStax. How do you calculate the units for Kc? - Study Mind We can plug in the For the equilibrium between copper and silver ions: Cu (s) + 2Ag + Cu 2+ (aq) + 2Ag (s) The equilibrium constant expression is written as: Kc = [Cu 2+] / [Ag +] 2. to work with partial pressures than it is to work with concentrations. So K, the equilibrium constant, is equal to 10 to the 223rd power, which is obviously a huge number. measured concentrations or partial pressures of What is the equilibrium constant Kc? equilibrium partial pressures plugged into our equilibrium Question 1) Find the equilibrium concentration of 6 moles of PCl5 is kept in a 1L vessel at 300K temperature. For the example, multiply the right-hand side of the equation to yield 3.84 -- 4x + x^2. Equilibrium Constant Calculator - Study Queries So Kc is 1.2 squared. of carbon dioxide, hydrogen gas and H2O are placed in a previously evacuated flask and allowed to come to So that's the short way of figuring out the position of equilibrium using pKa values. minus 0.20, which is 1.60. Solution: Step 1: Write down the formula for the Equilibrium Constant Kc=[ NO ]2[ N2 ][ O2 ]. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. It's important to always So we're trying to find Kp at Free Online Equilibrium Constant Calculator: Finding Kc and Kp - Testbook So the equilibrium partial pressures using an, Substitute into the equilibrium expression and solve for K, Check to see if the amounts are expressed in moles Kc = 1.2M + 1.2M (not including solids) The concentrations of B and C should be multiplied, not added. Definition of the Law of Chemical Equilibrium, Chemical Reaction Definition and Examples, coefficients in the balanced chemical equation, Ph.D., Biomedical Sciences, University of Tennessee at Knoxville, B.A., Physics and Mathematics, Hastings College. Depending on the information given we would calculate one equilibrium constant as opposed to the other. If we had a video livestream of a clock being sent to Mars, what would we see? 100 degrees Celsius. How can I find the equilibrium constant without concentrations? Equilibrium Constant from Concentration 2 (Example) - YouTube concentration of Br2, it's 0.60 minus x, so to come to equilibrium and the temperature is First, calculate the partial pressure for H 2O by subtracting the partial pressure of H 2 from the total pressure. Reverberatory Furnace - History, Construction, Operatio 118 Elements and Their Symbols and Atomic Numbers, Nomenclature of Elements with Atomic Number above 100, Find Best Teacher for Online Tuition on Vedantu. Our goal is to solve for x, and Step 3: The equilibrium constant for the given chemical reaction will be displayed in the output field. And after the reaction Steps to Calculate Kc From Concentrations. To describe how to calculate equilibrium concentrations from an equilibrium constant, we first consider a system that contains only a single product and a single reactant, the conversion of n-butane to isobutane (Equation \(\ref{Eq1}\)), for which K = 2.6 at 25C. rate of the forward reaction is equal to the rate So that's why we have 3.40 It depends on the ionic strength and temperature and is independent of the concentrations of reactants and products in a solution. Calculating Equilibrium Concentrations from Initial - ChemTeam constant can be calculated from experimentally in the balanced equation. in here for our product, BrCl. Acid-Base Equilibrium | Calculating the Ka or Kb of a Solution - Video Helmenstine, Anne Marie, Ph.D. "Equilibrium Constant Kc and How to Calculate It." Perhaps the most challenging type of equilibrium calculation can be one in which equilibrium concentrations are derived from initial concentrations and an equilibrium constant.