The concept of ionic equilibrium and chemical equilibrium forms the basis of learning the topic electrochemistry which is an important topic from both JEE and NEET point of view. The fundamental concepts of this topic can be built from ncert class 11th and 12th book. For furthermore clarification or the concepts explained in even simpler language, students can refer to books of class 11th and 12th by the Maharashtra board.
What is ionic equilibrium?
Ionic equilibrium can be defined as equilibrium between the unionized molecules and the ions in the solutions of weak electrolyte.
Example: acetic acid breaking up into acetate ions and hydrogen ions:
CH3 COOH → CH3 COO– + H+
What are electrolytes?
These are the chemical substances that can conduct electricity in their aqueous state or in molten state.
Types of electrolytes:
- Strong electrolytes: The electrolytes that are almost completely dissociated into ions in solution are called strong electrolytes. For example: KCl, HCl, NaOH, NH4NO3
- Weak electrolytes: These kinds of electrolytes do not ionize completely in solution.it is called weak electrolytes.
Understanding the concept of ionic product:
In aqueous solution or in pure water, the product of concentrations of hydrogen and hydroxyl ions is a constant at a given temperature. This is called ionic product of water and is designated by Kw.
The idea of the ionic product of water can be understood by understanding the autoionization reaction of water that may be expressed as:
H2O+H2O=H3O+ +OH- H2O + H2O = H3O+ + OH–
Kw = CH3 O+ COH–
The value of Kw at 25°C is 1*10-14.
Subtopics that come under IONIC Equilibrium is:
- concepts of acids and bases and salts, and its relevance for ionic equilibrium
- define conjugate acid-base pairs and identify them in an acid-base equilibrium
- derive the expressions for the ionization constants of weak acids and bases
- define and explain common ion effect in ionization of weak acids and bases
- correlate the ionization constants and the strength of acids and bases
- explain self-ionization of water and derive an expression for its ionic product
- define pH and correlate it with the nature of aqueous solutions- neutral, acidic or basic
- define buffer solutions
- Henderson equation to calculate the pH of acidic and basic buffers
- express solubility equilibrium with the help of an equation
- explain hydrolysis of salts with the help of chemical equations
- understanding the concept of common ion effect on solubility equilibrium and Chemical Dynamics and recall some applications of common ion effect.
- identifying relations between solubility and solubility product for salts of AB, AB2 A2B and A2B3 types
Summarizing few concepts:
- IONIC equilibrium in short is the equilibria involving ionic species. The equilibria involved with acid and bases are used widely.
- Buffer solutions resists a change in its pH on adding a small amount of an acid or a base. Using the buffer solutions for pH control is of great significance in living systems, agriculture and industrial processes. Likewise, the solubility equilibrium established in the solutions of sparingly soluble salts is also very important. Example our bones and teeth are mostly calcium phosphate, Ca3(PO4)2 is a slightly soluble salt.
- SALTS: it is the product of reaction between acid and a base. Such reactions are called neutralization reaction.
One cannot define acids and bases generally. However there are three different concepts of acids and bases proposed by Arrhenius, Brønsted and Lowry and Lewis respectively which are well known.
It may not be the most important topic from both NEET and JEE point of view, but since it forms a basis for electrochemistry it should not be avoided in anyway. It is often observed that a question is asked in JEE MAINS and around 2-3 questions is asked in NEET EXAMS from time to time.
Once the students have completed the chapter and other interlinked chapters, it is advisable for them to practice Multiple choice questions, either from the materials provided by the coaching institutes or any other reference material of the students’ choice. It is important to know that students must refrain from consulting more than two source. A dedicated focused study is a must for all students. Multiple revisions is also advised.
While self-study is extremely important, students are advised to refer to coaching notes for further clarification and assessment. Doubtnut.com is one such online platform that provides a comprehensive, in depth and most importantly focused study for students from grade 6th to 12thand also specializes in providing coaching for JEE and NEET competitive exams. Online classes are provided at a minimal cost. Periodical quizzes and test are held for self-assessment. It provides video solutions for the students who attend video lectures. As the videos are uploaded every day, students can go through multiple such video solutions covering various topics. The Doubtnut app can be downloaded from Google play.
Can you solve this question: 50 mL of 0.1 M HCl and 50 mL of 2.0 M NaOH are mixed. The pH of the resulting solution is?