NCERT Class 12 Chemistry Solutions Surface Chemistry

NCERT Class 12 Chemistry Solutions Surface Chemistry - NCERT Solutions prepared for CBSE students by the best teachers in Delhi. 

Class XII  Chemistry

Chapter 5 – Surface Chemistry

Question 1:

Write any two characteristics of Chemisorption.

Answer

1. Chemisorption is highly specific in nature. It occurs only if there is a possibility of chemical bonding between the adsorbent and the adsorbate.

2. Like physisorption, chemisorption also increases with an increase in the surface area of the adsorbent.

 

Question 2:

Why does physisorption decrease with the increase of temperature?

Answer

Physisorption is exothermic in nature. Therefore, in accordance with Le-Chateliere’s principle, it decreases with an increase in temperature. This means that physisorption occurs more readily at a lower temperature.

 

Question 3:

Why are powdered substances more effective adsorbents than their crystalline forms?

Answer

Powdered substances are more effective adsorbents than their crystalline forms because when a substance is powdered, its surface area increases and physisorption is directly proportional to the surface area of the adsorbent.

 

Question 4:

Why is it necessary to remove CO when ammonia is obtained by Haber’s process?

Answer

It is important to remove CO in the synthesis of ammonia as CO adversely affects the activity of the iron catalyst, used in Haber’s process.

 

Question 5:

Why is the ester hydrolysis slow in the beginning and becomes faster after sometime?

Answer

Ester hydrolysis can be represented as:

The acid produced in the reaction acts as a catalyst and makes the reaction faster. Substances that act as catalysts in the same reaction in which they are obtained as products are known as autocatalysts.

 

Question 6:

What is the role of desorption in the process of catalysis?

Answer

The role of desorption in the process of catalysis is to make the surface of the solid catalyst free for the fresh adsorption of the reactants on the surface.

 

Question 7:

What modification can you suggest in the Hardy-Schulze law?

Answer

Hardy-Schulze law states that ‘the greater the valence of the flocculating ion added, the greater is its power to cause precipitation.’

This law takes into consideration only the charge carried by an ion, not its size. The smaller the size of an ion, the more will be its polarising power. Thus, Hardy-Schulze law can be modified in terms of the polarising power of the flocculating ion. Thus, the modified Hardy-Schulze law can be stated as ‘the greater the polarising power of the flocculating ion added, the greater is its power to cause precipitation.’

 

Question 8:

Why is it essential to wash the precipitate with water before estimating it quantitatively?

Answer

When a substance gets precipitated, some ions that combine to form the precipitate get adsorbed on the surface of the precipitate. Therefore, it becomes important to wash the precipitate before estimating it quantitatively in order to remove these adsorbed ions or other such impurities.

 

Students should free download the NCERT solutions and get better marks in exams. Studiestoday.com panel of teachers recommend students to practice questions in NCERT books and download NCERT solutions.

Tags: 

 


Click to View or Download pdf file
Click for more Chemistry Study Material

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

Board Exams helpline by CBSE

According to the recent announcement of CBSE, the pending Class 10 and 12 Board exams are going to be held from 01 July to 15 July 2020 in India. Along with this, it has also been decided to resume the free of cost tele-counseling service for students from 9.30 am to 5...

Cogito and The Question Book A series on Thinking skills by CBSE

The Board has dedicated this academic session 2020-21 for ‘Competency Based Learning’. Skills connected to Critical & Creative thinking, Problem Solving, Collaboration and Communication are core to successful living in the 21st Century. To focus on the importance...

CBSE Reduced Syllabus Clarification

CBSE board has issued the following clarification relating to various news reports regarding reduction in syllabus and questions from the reduced syllabus during board exams. Please read below: It has come to notice of the Board through a section of media reports that...

CBSE Reduced Syllabus Class 11 and 12

CBSE has announced major reduction in the syllabus for class 11 and class 12. There has been major changes too in the main syllabus for class 11 and 12. The prevailing health emergency in the country and at different parts of the world as well as the efforts to contain...

Training Programme on the Alternative Academic Calendar

In view of the extraordinary situation prevailing in the world due to COVID-19 pandemic, the CBSE Board had announced the ‘Revised Academic Curriculum for classes 9- 12 for the session 2020-21’. The reduced topics will not be part of the internal assessment or for the...

CBSE tele counselling for board exams

The 23rd edition of post-result counselling facility will be activated by CBSE with the help of 95 volunteer principals and trained counsellors from within affiliated schools located in and outside India. While there are 73 Counsellors in India including special...

×
Studies Today