# Finding equilibrium constant kc

Alternatively you might have Finding equilibrium constant kc calculate equilibrium concentrations from a given value of Kc and given starting concentrations.

It applies where everything in the equilibrium mixture is present as a gas, or everything is present in the same solution.

Questions to test your understanding If this is the first set of questions you have done, please read the introductory page before you start. That means that all the powers in the equilibrium constant expression are "1".

Calculations involving Kc There are all sorts of calculations you might be expected to do which are centred around equilibrium constants. Those powers the order of the reaction with respect to each of the reactants are experimentally determined.

Use the BACK button on your browser to return to this page. At room temperature, this value is approximately 4 for this reaction. The equilibrium produced on heating calcium carbonate This equilibrium is only established if the calcium carbonate is heated in a closed system, preventing the carbon dioxide from escaping.

The Finding equilibrium constant kc the powers that you have to raise the concentrations to - for example, squared or cubed or whatever are just the numbers that appear in the equation. That is all that is left in the equilibrium constant expression.

This time the Kc expression will include some visible powers: You could only do that for the very simple cases where the reaction took place in a single step represented by the given equation.

Taking another look at the two examples above, and adding a third one: Writing an expression for Kc We are going to look at a general case with the equation: If you shake copper with silver nitrate solution, you get this equilibrium involving solids and aqueous ions: Although everything is present as a gas, you still measure concentrations in mol dm If you compare this with the previous example, you will see that all that has happened is that the expression has turned upside-down.

No state symbols have been given, but they will be all gor all lor all aq if the reaction was between substances in solution in water. The equilibrium produced on heating carbon with steam Everything is exactly the same as before in the equilibrium constant expression, except that you leave out the solid carbon.

Kc in heterogeneous equilibria Typical examples of a heterogeneous equilibrium include: If you know about orders of reaction and rate equations, you will find this very easy to follow. It is really important to write down the equilibrium reaction whenever you talk about an equilibrium constant.

Compare this with the chemical equation for the equilibrium. A homogeneous equilibrium has everything present in the same phase. If you allow this reaction to reach equilibrium and then measure the equilibrium concentrations of everything, you can combine these concentrations into an expression known as an equilibrium constant.

It is much easier to do this from a carefully structured book giving you lots of worked examples and lots of problems to try yourself.

The equilibrium in the hydrolysis of esters This is the reverse of the last reaction: The Contact Process equilibrium You will remember that the equation for this is: That is the only way that you can be sure that you have got the expression the right way up - with the right-hand substances on Finding equilibrium constant kc top and the left-hand ones at the bottom.

You will find a link to that at the bottom of the page. That is dangerously misleading. The equilibrium established if steam is in contact with red hot carbon.

A heterogeneous equilibrium has things present in more than one phase. Some specific examples The esterification reaction equilibrium A typical equation might be: The equilibrium produced between copper and silver ions Both the copper on the left-hand side and the silver on the right are solids.

The convention is that the substances on the right-hand side of the equation are written at the top of the Kc expression, and those on the left-hand side at the bottom. This is simply too huge a topic to be able to deal with satisfactorily on the internet. The Kc expression is:This example problem demonstrates how to find the equilibrium constant of a reaction from equilibrium concentrations of reactants and products.

The equilibrium constant is the value of the reaction quotient that is calculated from the expression for chemical equilibrium. It depends on the ionic strength and temperature and is independent of the concentrations of reactants and products in a solution. This page explains what is meant by an equilibrium constant, introducing equilibrium constants expressed in terms of concentrations, K c.

It assumes that you are familiar with the concept of a dynamic equilibrium, and know what is meant by the terms "homogeneous" and "heterogeneous" as applied to chemical reactions. Chemical Equilibrium: Finding a Constant, K c Chemistry with Vernier 20 - 3 4.

Prepare a blank by filling a cuvette 3/4 full with distilled water. To correctly use cuvettes, remember: • Wipe the outside of each cuvette with a lint-free tissue. • Handle cuvettes only by the top edge of the ribbed sides.

Definition of equilibrium constant Kp for gas phase reactions, and how to calculate Kp from Kc. Using Known K's for Other Reactions.

K for a Reversed Reaction; Reaction Coefficients Multiplied by a Number; If two or more reactions are added to give another, the equilibrium constant for the reaction is the product of the equilibrium constants of the equations added.

K' = K 1 x K K 1.

Finding equilibrium constant kc
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