Applications Of Equilibrium Constants
Chapter Name : Equilibrium |
Sub Topic Code : 102_11_07_07_03 |
Topic Name : Applications Of Equilibrium Constants |
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Sub Topic Name : Calculating Equilibrium Concentrations |
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Introduction
To calculate the equilibrium concentration from the initial concentrations 5 steps are followed: • Write the balanced equation for the reaction. • Under the balanced equation, make a table: that lists for each substance involved in the reaction: (a) The initial concentration. (b) The change in concentration on going to equilibrium. (c) The equilibrium concentration. • In the table, define x as the concentration (mol/L) of one of the substances that reacts on going to equilibrium, then determine the concentrations of the other substances in terms of x. • Substitute the equilibrium concentrations into the equilibrium equation for the reaction and solve for x. • At times you may have to solve quadratic equation to find x. • Calculate the equilibrium concentrations (or partial pressure if calculating for Kp) from the calculated value of x. • Check your results by substituting them into the equilibrium equation.
Pre-Requisites:
Reaction, equilibrium constant
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
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| Reaction quotient | • The reaction quotient, Q. • (Qc with molar concentrations and Qp with partial pressures) is defined in the same way as the equilibrium constant Kc except that the concentrations in Qc are not necessarily equilibrium values. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Liquid water and water vapor in a closed container | • Heterogeneous equilibrium mixture example. |
Practical examples around us
| Examples | Explainations |
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What you learn in Theory:
To calculate the equilibrium concentration from the initial concentrations 5 steps are followed: • Write the balanced equation for the reaction. • Under the balanced equation, make a table: that lists for each substance involved in the reaction: (a) The initial concentration. (b) The change in concentration on going to equilibrium. (c) The equilibrium concentration. • In the table, define x as the concentration (mol/L) of one of the substances that reacts on going to equilibrium, then determine the concentrations of the other substances in terms of x. • Substitute the equilibrium concentrations into the equilibrium equation for the reaction and solve for x. • At times you may have to solve quadratic equation to find x. • Calculate the equilibrium concentrations (or partial pressure if calculating for Kp) from the calculated value of x. • Check your results by substituting them into the equilibrium equation.
What you learn in Practice:
• The equilibrium constant helps in predicting the direction in which a given reaction will proceed at any stage. We calculate the reaction quotient Q, to predict the direction of the reaction.