What will affect equilibrium constant

Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney. Hanley Rd, Suite St. Louis, MO Subject optional. Email address: Your name:. Consider the following balanced reaction:. Possible Answers:. Correct answer:. Explanation : When writing the equilibrium expression for a reaction, remember that the products are on the top of the expression and the reactants are on the bottom.

A general formula and corresponding equilibrium expression are given here: Our equation follows the same format. Report an Error. Consider the following reaction:. A general formula and corresponding equilibrium expression are given here: Our equation has only one product, but follows the same format.

What equation gives the equilibrium constant for the following reaction? Explanation : The general formula for the equilibrium constant of a reaction is: For gaseous reactions, however, partial pressure can be substituted for concentration. Which of the following will affect the equilibrium constant of a reaction? Possible Answers: None of these will affect the reaction equilibrium constant.

Ratio of substrate concentration to product concentration. Correct answer: None of these will affect the reaction equilibrium constant. Explanation : The equilibrium constant gives the ratio of product concentration to reactant concentration that results in equal forward and reverse rates of reaction.

Explanation : When creating the solubility product expression for a salt, keep in mind that salts are solids, and are therefore not included in the expression. For a general reaction, the solubility product constant would be given as follows: Aluminum hydroxide will dissociate based on the following balanced reaction: As a result, the solubility product expression is:.

Example Question 9 : Chemical Equilibrium. What is the difference between the reaction quotient and the equilibrium constant? Possible Answers: The equilibrium constant is valid only at equilibrium, and the reaction quotient can be calculated at any given moment in the reaction. The reaction quotient is equivalent to the rate law.

Dynamic equilibrium is established when the rates of the forward and back reactions become equal. If a catalyst speeds up both reactions to the same extent, then they will remain equal without any need for a shift in position of equilibrium. Note: If you know about the Arrhenius equation , it isn't too difficult to use it to show that the ratio of the rate constants for the forward and back reactions isn't affected by adding a catalyst.

Although the activation energies for the two reactions change when you add a catalyst, they both change by the same amount. I'm not going to do this bit of algebra, because it would never be asked at this level UK A level or equivalent. If this is the first set of questions you have done, please read the introductory page before you start. Changing concentrations The facts Equilibrium constants aren't changed if you change the concentrations of things present in the equilibrium. Suppose you have an equilibrium established between four substances A, B, C and D.

Explanation in terms of the constancy of the equilibrium constant The equilibrium constant, K c for this reaction looks like this: If you have moved the position of the equilibrium to the right and so increased the amount of C and D , why hasn't the equilibrium constant increased?

This is actually the wrong question to ask! We need to look at it the other way round. If you decrease the concentration of C: Changing pressure This only applies to systems involving at least one gas. The facts Equilibrium constants aren't changed if you change the pressure of the system.

Explanation Where there are different numbers of molecules on each side of the equation Let's look at the same equilibrium we've used before. Because this is an all-gas equilibriium, it is much easier to use K p : Once again, it is easy to suppose that, because the position of equilibrium will move to the right if you increase the pressure, K p will increase as well. To understand why, you need to modify the K p expression. Remember the relationship between partial pressure, mole fraction and total pressure?

Use the BACK button on your browser to return to this page. Replacing all the partial pressure terms by mole fractions and total pressure gives you this: If you sort this out, most of the "P"s cancel out - but one is left at the bottom of the expression. Where there are the same numbers of molecules on each side of the equation In this case, the position of equilibrium isn't affected by a change of pressure.

Why not? Let's go through the same process as before: Substituting mole fractions and total pressure:. Therefore the ratio between reactant and product concentrations will remain the same. This is a lesson from the tutorial, Chemical Equilibrium and you are encouraged to log in or register , so that you can track your progress.

Log In. Register or login to receive notifications when there's a reply to your comment or update on this information. Don't want to keep filling in name and email whenever you want to comment? Register or login to make commenting easier. Save my name, email, and website in this browser for the next time I comment. Decreasing the terms on the bottom means that you have decreased the mole fractions of the molecules on the left.

That is another way of saying that the position of equilibrium has moved to the right - exactly what Le Chatelier's Principle predicts. There are the same numbers of molecules on each side of the equation.

In this case, the position of equilibrium is not affected by a change of pressure. Why not? Equilibrium constants are changed if you change the temperature of the system. Look at the equilibrium involving hydrogen, iodine and hydrogen iodide:. This is typical of what happens with any equilibrium where the forward reaction is exothermic.

Increasing the temperature decreases the value of the equilibrium constant. Where the forward reaction is endothermic, increasing the temperature increases the value of the equilibrium constant. The position of equilibrium also changes if you change the temperature. If you increase the temperature, the position of equilibrium will move in such a way as to reduce the temperature again. It will do that by favoring the reaction which absorbs heat.