Students preparing for class 12 board examinations are advised to solve NCERT questions, solving the NCERT Solutions will help them to understand the chapter. Download the NCERT solutions of class 12 Maths, Physics and other subjects prepared on the basis of latest CBSE Syllabus for 2020 – 2021.This section also contains assignments, revision book and revision of chapters with question – … (iv) The products are diffused away from the catalyst surface. substance”. cbse class 12 maths ncert solutions Chapter 5. NH3 gets adsorbed on the charcoal where as NH3 when comes in contact with H20 gets absorbed by forming NH4OH solution of uniform concentration. where x is the mass of the gas adsorbed by mass ‘m’ of the adsorbent at pressure P, k and n are constants which depend on the nature of the adsorbent and the gas at a particular temperature. Solution: The role of an emulsifier in stabilising an emulsion can be explained in two ways: The NCERT Solutions for Class 12 Chemistry helps students to understand the questions structured as per the CBSE guidelines. This chapter is about the properties and behaviour of gasses and liquids. NCERT Solutions for class 12 Science Chemistry solved by subject matter experts. This is achieved by increasing the surface area and also the number of pores and vacant sites (active centres) per unit area. For example, on dipping a chalk stick into an ink solution, there is only a color change on its surface and it will be found to be white from inside when the chalk stick is broken. Why (c) Micelle formed. Soln: One of the criteria of classifying colloids is the physical state of the dispersed phase and dispersion medium. NCERT Books & Solutions, Assignments, Sample Papers, Notes and books for revision are available to download. Soln: Rate of adsorption of … NCERT Solutions class 12 Maths Exercise 5.5 Class 12 Maths book solutions are available in PDF format for free download. Solution: Emulsions: It is a colloidal system in which both the dispersed phase and the dispersion medium are liquids, e.g., milk consists of small drop’s of liquid fat dispersed in water. The d-and f-Block Elements. Ans: The ester hydrolysis takes place as follows : They have to be desorbed from the surface so that more the reactants may be accommodated on the surface of the catalyst. on solids. NCERT Solutions for Class 12 Chemistry: The NCERT solutions provided here will enhance the concepts of the students, as well as suggest alternative methods to solve particular problems to the teachers.The target is to direct individuals towards problem solving strategies, rather than solving problems in one prescribed format. (iii) The colloidal particles are charged and carry either a positive or negative charge. Students will be able to get a clear overview of the concepts covered in each chapter and improve their confidence to score well in the board exams. Enthalpy of adsorption is high as chemical bonds are formed. - 8. he chapter is easy to follow but demands a clear conceptual understanding of the topics.If you have studied the chapter, then now it is the time to test your understanding by solving the exercise questions. Question 5.26: Explain the terms with suitable examples: A colloidal solution having a solid substance as the dispersed phase and alcohol as the dispersion medium is called an alcosol. It is done by : Pressure: At constant temperature, the adsorption of gas increases with pressure. Sometimes the questions from the NCERT books are asked directly in the examination just by changing the numerical values, so it is important that students must try to solve all the NCERT questions provided at the end of this chapter. These solutions for Biomolecules are extremely popular among Class 12 Science students for Chemistry Biomolecules Solutions come handy for quickly completing your homework and preparing for exams. If somehow, the charge is removed, the particles will come nearer to each other to form aggregates (or coagulate) and settle down under the force of gravity. Soln: Emulsion is defined as the colloidal solution in which both the dispersed phase and dispersion medium are liquids. Solution: Soap is sodium or potassium salt of a higher fatty acid and may be represented as RCOO–Na+ (e.g., sodium stearate CH3(CH2 )16 COO–Na+ which is a major component of many bar soaps). Gaseous molecules are then adsorbed on the surface of the catalyst. The molecules and ions diffuse through membrane into the outer water and pure colloidal solution is left behind. Question 5.2: What is the difference between physisorption and chemisorption? Such colloids are called aggregated colloids. In this type of adsorption, the adsorbate and the surface of the adsorbent are bonded with strong chemical bonds. The catalytic activity of a metal for hydrogenation increases as we move from Group 5 metals to Group 11. In absorption, the substance gets uniformly distributed throughout the bulk of the solid or liquid. It is an example of mono-layer adsorption. Ans: According to Hardy Schulze law, the coagulating ion has charge opposite to that on the colloidal particles. Soln: The surface phenomenon of crowding up of molecules of a substance at the base surface rather than in the mass (bulk) of a solid or liquid is called Adsorption. For example, catalysis by zeolites is a shape-selective catalysis. (i) a beam of light is passed through colloidal sol The concentration of the substance remains at the surface only in the case of adsorption. The maximum activity is shown by metals of Groups 7, 8 and 9. The reactant molecules are adsorbed on the surface of the solid catalyst by physical adsorption or chemisorption. NCERT Solutions for Class 12 Chemistry Chapter 2 contains solved questions asked in the textbook. Question 5.15: Explain what is observed Small molecules and ions can pass through animal membranes unlike colloidal particles is the main principle of this process. The apparatus used for this purpose is called dialyser. Your email address will not be published. (b) Lyophobic colloids (solvent hating) are those substances that do not form the colloidal sol readily when mixed with the dispersion medium. Give an example of a micellers system. (ii) At a constant temperature, adsorption increases with pressure. Soln: Zeolites are alumino-silicates that are micro-porous in nature. (ii) nature of dispersed phase and (b) Selectivity: The selectivity of a catalyst is its ability to direct a reaction to yield a particular product. Various cavities are present with characteristic shapes, on the surface of the enzymes. ... NCERT Solutions for Class 12 Maths Chapter 5 Miscellaneous Exercise 5 … 5.16. Freundlich, in 1909, gave an empirical relationship between the quantity, of gas adsorbed by unit mass of solid adsorbent and pressure at a particular temperature. They are microporous aluminosilicates with three dimensional network of silicates in which some silicon atoms are replaced by aluminium atoms giving Al-O-Si framework. Solution: Book: National Council of Educational Research and Training (NCERT) Coordination Compounds. (iii) Oswald’s process: Oxidation of ammonia to nitric oxide in the presence of platinum. Free downloadable chapter wise NCERT solutions for class 12 Science Chemistry in PDF format to help students in homework and score good marks in test and exams. The NCERT Class 12th Chemistry textbooks are well known for it’s updated and thoroughly revised syllabus. What are the factors which influence the adsorption of a gas on a solid? What are enzymes? What are their different types? (ii) Lyophobic sols: Colloidal sols are not formed, when substances such as metals and their sulphides are mixed with the dispersion medium. The negatively charged sheath around the globules prevents them from coming together and forming aggregates. Solution: A colloidal state is intermediate between a true solution and a suspension. (b) Water-in-oil type in which water droplets are dispersed in an oil medium, e.g., butter. Some ions of the reactants may be adsorbed or may stick on the surface of the particles of the precipitate. NCERT Books chapter-wise Solutions (Text & Videos) are accurate, easy-to-understand and most helpful in Homework & Exam Preparations. The syllabus from 6 to 12 is designed keeping in view of higher classes and each class is interconnected. Give one example in each case. (iv)Emulsification is used to make medicines. What are their different types? How is it achieved? Soln: Adsorption is always exothermic. (c) Associated colloids (Micelles): Those colloids which behave as normal strong electrolyte at low concentration but show colloidal properties at high concentration due to the formation of aggregated particles of colloidal dimension’s. The RCOO– ions, however, consist of two parts – a long hydrocarbon chain R (also called non-polar ‘tail’) which is hydrophobic (water repelling), and a polar group COO– (also called polar- ionic ‘head’), which is hydrophilic (water loving). What role does adsorption play in heterogeneous catalysis? They can form ions and may contain 100 or more molecules to form a micelle. NCERT CBSE latest book edition solutions. 5.12. Discuss the effect of pressure and temperature on the adsorption of gases on solids. Therefore, ΔG=ΔH–TΔS\Delta G = \Delta H – T\Delta SΔG=ΔH–TΔS. Thus, in accordance with Le-Chatelier’s principle, the magnitude of adsorption decreases with an increase in temperature. For example, sodium chloride behaves as crystalloid in water but as colloid in benzene solvent. Get here NCERT Solutions for Class 12 Chemistry Chapter 5. Hence, we can say that a colloidal substance does not represent a separate class of substances. Comment. Solution: Adsorption isotherm represents the variation of the mass of the gas adsorbed per gram of the adsorbent with pressure at constant temperature. Thus, molecules having a pore size more than 260-740 pm cannot enter the zeolite and undergo the reaction. Give one example of each. Question 5.11: What are lyophilic and lyophobic sols? The relationship is generally represented in the form of a curve where mass of the gas adsorbed per gram by the adsorbent is plotted against pressure. (iii) electric current is passed through a colloidal sol? Question 26. An empirical relationship between the quantity of gas adsorbed by the unit mass of solid adsorbent and pressure at a specific temperature is given by Freundlich adsorption isotherm. Question 5.23: Explain the following terms: An applied electric field influences the colloidal particles to move randomly, this is known as electrophoresis. Thus, when negatively charged Cl– ions are present, ferric oxide sol particles gets coagulated. Question 5.25: What are micelles? Ans: In the heterogeneous catalysis carried over metal surface, adsorbed reactant species combine to form the products. These curves indicate that at a fixed pressure, there is a decrease in physical adsorption with increase in temperature. It is an example of multi-layer adsorption. Solution: Colloids can be classified into eight types depending upon the physical state of the dispersed phase and the dispersion medium. 5.19. Adsorption increases with an increase in pressure and, as a result adsorption is a reversible process and is accompanied by a decrease in pressure. This phenomenon takes place as particles of colloidal dimensions scatter light in all directions. However, at higher concentrations, due to the formation of aggregated particles these substances behave like colloidal solutions. Comment on the statement that colloid is not a substance but a state of substance. 5.7. Photographic films are coated with emulsion of AgBr on its surface. Worksheets and exercises provided in surface chemistry and NCERT solutions will help you in understanding the concepts of the chapter surface chemistry. This leads to a decrease in the entropy of the gas i.e., ∆S is negative. with a suitable liquid (dispersion medium). It does not penetrate through the surface to the bulk of the solid or liquid. How are the colloidal solutions classified on the basis of physical states of the dispersed phase and dispersion medium? How a re associated colloids different from these two types of colloids? Delhi 2008, 2009; Outside Delhi, 2010, 2011) The activation can be achieved in a number of ways. This is known as the Tyndall effect. Adsorption is an exothermic process. Activation of adsorbent: It means increasing the adsorbing power of an adsorbent by increasing its surface area. It is not specific in nature, i.e. Book: National Council of Educational Research and Training (NCERT) Class 12 Chemistry Chapter 5 Surface Chemistry is an important chapter and explains the types of chemical reactions, its pocesses and mechanisms that take place at the surface of the material. Solution: Question 25. NCERT s olutions for class 12 chemistry chapter 5 Surface Chemistry - In this chapter, some important features of surface chemistry will be discussed like catalysis, adsorption and collides including emulsions and gels. Complementary shape of the reactant molecules fit into the cavities just like a key fits into a lock. This process is called the Haber’s process. Furthermore, this separating of the bulk phases is by a hyphen or a slash. NCERT Solutions for Class 11 Chemistry Chapter 5: States of Mater is a very basic and important chapter which candidates need to study and understand thoroughly. When the same beam of light is passed through a colloidal solution, scattering of light takes place. Exam pattern and CBSE syllabus an emulsion be used for reference a from... Science Chemistry Chapter 5 Continuity and Differentiability all exercises with Miscellaneous exercises in Hindi English. 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