Etiket Arşivleri: equilibrium constant

Chemical Equilibrium Notes

Chemical Equilibrium

Chapter 15

Introduction

Lets consider the catalytic methanation reaction

The Equilibrium Constant

Some equilibrium compositions for the methanation reaction

Example 

The Law of Mass Action

The manipulation rules of equilibrium constants

Heterogeneous Equilibria

Calculating Equilibrium Constants

Example

USING THE EQUILIBRIUM CONSTANT

we described how a chemical reaction reaches equilibrium.

how this equilibrium can be characterised by the equilibrium constant.

Applications of Equilibrium Constants

Predicting the direction of Reaction.

Calculating Equilibrium Concentrations

If Qc > Kc, the reaction will go left

If Qc < Kc, the reaction will go right

If Qc = Kc, the reaction is at equilibrium

Example

Three steps in solving equilibrium concentrations:

Set up a table of concentrations.

Substitute the expressions in x for equilibrium concentrations into the equilibrium constant expression.

Solve the equilibrium constant expression for the values of the equilibrium concentrations.

Changing the Reaction Conditions:

Le Chatelier’s Principle

Change in Reactant or Product Concentrations

Effects of Volume and Pressure Changes

Example

The Effect of Catalyst


Laboratory‎ > ‎Chemical Equilibrium

One useful application of Beer’s Law is to determine the equilibrium constant of a reaction. Reactants (iron (III) and thiocyanate) are mixed in a ratio such that one reactant is presumed to be nearly 100% converted into a colored product. The product is assumed to follow Beer’s Law, and the relationship between relative absorbance and concentration is determined from the first experiment. After that, the reactant originally in excess is reduced in concentration. From the colorimetric determination of product concentration, the concentrations of reactant remaining at equilibrium is determined and the quantitative relationships among these concentrations are studied. One of these relationships, the mass action expression, is found to be nearly constant.

Laboratory‎ > ‎Determination of Equilibrium Constant

In this experiment , we were cleaned flasks and we marked 1,2,3 and 4. We added indicator and 20 mL of distilled water into the each flasks. We added NaOH from burette into the each flasks and we determined volume of NaOH for each flasks.When the color of solution change we closed the burette. We found the volume of spilled NaOH for each flasks and we reached the equilibrium.