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P-Block Elements Learning Sheet Solution-9 Gxii-Chem

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P-Block Elements Learning Sheet Solution-9 Gxii-Chem P-BLOCK ELEMENTS LEARNING SHEET SOLUTION-9 GXII-CHEM-p_block_elements_LSS9 The NCERT textbook content is given on Chapter7.pdf and Chapter8.pdf Answer the following questions 1. Which are the major ways of obtaining chlorine? Ans: The most way common method of preparing chlorine gas in the laboratory is by using manganese dioxide to oxidize hydrochloric acid, as shown by this equation: 2. How chlorine acts as a raw material for the preparation of new compounds? Ans: Common salt is formed by the reaction between hydrochloric acid and sodium hydroxide. Bleaching powder is synthesized by the action of chlorine gas (produced from the chlor-alkali process) on dry slaked lime Ca(OH)2.Sodium hydroxide is synthesized through the chloralkali process. Answer the following questions 3. When HCl reacts with finely powdered iron, it forms ferrous chloride and not ferric chloride. Why? Ans: Fe reacts with HCl to form FeCl₂ and H₂ Fe + 2 HCl ---> FeCl₂ + H₂ H₂ thus liberated prevents the oxidation of FeCl₂ to FeCl₃. 4. What is aqua regia? Ans: Aqua regia is a mixture of hydrochloric acid (HCl) and nitric acid (HNO3) at a ratio of either 3:1 or 4:1. It is a reddish-orange or yellowish-orange fuming liquid. The term is a Latin phrase, meaning "king's water". The name reflects the ability of aqua regia to dissolve the noble metals gold, platinum, and palladium etc. 5. Write the equation/s of formation of aqua regia. Ans: It is mixing of concentrated hydrochloric acid and concentrated nitric acid, chemical reactions occur. These reactions result in the volatile products nitrosyl chloride and chlorine gas: HNO3 (aq) + 3 HCl (aq) → NOCl (g) + Cl2 (g) + 2 H2O (l) The fuming nature and characteristic yellow color of aqua regia gives a proof of its presence.. As the volatile products escape from solution, the aqua regia loses its potency. 6. Hydrochloric acid decomposes salts of weaker acids, e.g., carbonates, hydrogencarbonates, sulphites, etc.Give explaination to this statement alongwith the balanced chemical equations. Ans: Acids react with carbonates to form carbon dioxide gas. Carbonates such as calcium carbonate, CaCO₃, are ionic compounds. For example, CaCO₃ consists of Ca²⁺ ions and CO₃²⁻ ions. The carbonate ions are basic. They react with the H⁺ ions from an acid such as HCl to form carbonic acid. 2H⁺ + CO₃²⁻ → H₂CO₃ The carbonic acid is unstable and decomposes into CO₂ and water. H₂CO₃ → H₂O + CO₂ The overall equation (3) is the sum of equations (1) and (2) (1) CaCO₃ + 2HCl → CaCl₂ + H₂CO₃ (2) H₂CO₃ → H₂O + CO₂ (3) CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ Acids react with Bicarbonates to form Salt, Water and release Carbon Dioxide. Because carbon dioxide is a gas, the mixture will foam as carbon dioxide is produced and the gas expands in volume. For ex. NaHCO3+HCl→NaCl+CO2+H2O NaHCO3+H3CCOOH→H3CCOONa+CO2+H2O Potassium sulphite on reacting with hydrochloric acid releases sulphur dioxide (SO2) gas. K2SO3+2HCl→2KCl+H2O+SO2 7. What do you understand by purifying bone black? Ans: Bone black, also known as bone char is a form of charcoal which is produced by heating animal bones in limited amount of air. It is a very good adsorbent and thus used for removing coloured impurity of liquids. HCl is used to purify this bone char. 8. Can you showcase how HCl is used in medicine and laboratory reagent? Ans: HCl as Medicine Betaine hydrochloride is also used to treat abnormally low levels of potassium (hypokalemia), hay fever, “tired blood” (anemia), asthma, “hardening of the arteries” (atherosclerosis), yeast infections, diarrhea, food allergies, gallstones, inner ear infections, rheumatoid arthritis (RA), and thyroid disorders. HCl in lab/” It is one of the most extensive reagent used in laboratory for various chemical reactions. Answer the following questions 9. What is specific about fluorine in this group? Ans: Reasons for the anomalous behaviour of Fluorine are: Small size and highest electronegativity. Low F-F bond dissociation enthalpy. Absence of d-orbitals. Also go through the anamolous behavior of fluorine from NCERT 10. Write down the names and formulas of oxoacids of halogens. Ans:click here 11. Draw the structures of oxoacids of chlorine. Ans: Answer the following reactions 12. When can interhalogen compounds be formed? Ans: The halogens react with each other to form interhalogen compounds. The general formula of most interhalogen compounds is XYn, where n = 1, 3, 5 or 7, and X is the less electronegative of the two halogens. The compounds which are formed by the union of two different halogens are called inter halogen compounds. 13. Why the formula IF7 has been considered? Ans: IF7 is pentagonal bipyramidal. It is also known as distorted octahedral as it distort the perfect octahedral shape. 3 3 As per the VSEPR Theory, the structure of IF7 is pentagonal bipyramidal and its hybridisation is sp d , since its coordination number is 7. 14. Write down the preparation equations of formation of interhalogen compounds. Ans: The interhalogen compounds can be prepared by the direct combination or by the action of halogen on lower interhalogen compounds. The product formed depends upon some specific conditions, For e.g. , 437k - Cl 2+ F2 ----→2ClF (equal volume) 573 k Cl2 + 3F2 ------→ 2ClF3 (excess) 437 k I2 + Cl2 ----→ 2ICl (equimolar) I2 3Cl2 2ICl3 (excess) Br2 + 3F2 → 2BrF3 (dilute with water) Br2 + 5F2 → 2BrF5 (excess) Answer the following questions 15. Prepare a flowchart/concept map of properties of Interhalogen compounds. Ans : ( You may prepare it in your own individual way) 16. From the table 7.11 what are the exceptional compounds and what is their specific characteristic? Ans: You may kindly put it in your words from the explanation given under that topic in NCERT/video link observed of that relevant topic. 17. Deduce the molecular shape of BrF3 on the basis of VSEPR theory. Ans: The central atom Br has seven electrons in the valence shell. Three of these will form electron pair bonds with three fluorine atoms leaving behind four electrons. Thus, there are three bond pairs and two lone pairs. According to VSEPR theory, these will occupy the corners of a trigonal bipyramid. The two lone pairs will occupy the equatorial positions to minimize lone pair-lone pair and the bond pair lone pair repulsions which are greater than the bond pair-bond pair repulsions. In addition, the axial fluorine atoms will be bent towards the equatorial fluorine in order to minimize the lone-pair-lone pair repulsions. The shape would be that of a slightly bent ‘T’. Answer the following Question 18. Why is ICl more reactive than I2? Ans: Inter halogen bonds are weaker (it is between two different halogens like ICl) because of its partly ionic character due to difference in electro negativities while when same halogens form X2(like I2 ) molecules and they form covalent bonds which are stronger than inter halogen compound and weak bond obviously is more reactive than the stronger bond and that's why ICl is more reactive than I2. 19. What do you understand by the term fluorinating agent? Ans: Fluorinating agents refer to those active species which have fluorine as their electrophilic or nucleophilic component to incorporate fluorine ion into an organic compound. These agents include Hydrogen fluoride and fluorine gas but these are expensive and highly corrosive so there are alternatives like Antimony Trifluoride, Bismuth Trifluoride etc. 20. Show chemical reaction of production UF6 . Ans: U(s) + 3ClF3(l) → UF6(g) + 3ClF(g) Answer the following questions 21. What is the other name of group 18? Why so? Ans: Group 18 are referred to as noble gases or inert gases. This means that these elements are chemically inert and do not take part in any reaction. 22. What are pitchblende, monazite, and cleveite? Ans: Uraninite, formerly pitchblende, is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely UO₂, but due to oxidation the mineral typically contains variable proportions of U₃O₈. Additionally, due to radioactive decay, the ore also contains oxides of lead and trace amounts of helium. Monazite is a reddish-brown phosphate mineral containing rare-earth metals. To be more specific, it represents a group of minerals. Cleveite is an impure radioactive variety of uraninite containing uranium, found in Norway. It has the composition UO2 with about 10% of the uranium substituted by rare-earth elements. It was named after Swedish chemist Per Teodor Cleve. 23. Give the chemical reaction of the formation of 226Ra. 226 222 4 Ans: 88Ra → 86 Rn + 2 He Answer the following questions 24. List down the elements of group 18. Ans: The Group 18 elements include Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn). 25. Noble gases have very low boiling points. Why? Ans: Noble gases being monoatomic have no inter atomic forces except weak dispersion forces and therefore, they are liquefied at very low temperatures. Hence, they have low boiling points. 26. What is specific characteristic of group 18 elements? Ans: The specific characteristics of the noble gases are that they all conduct electricity, fluorescents, are odorless and colorless, and are used in many conditions when a stable element is needed to maintain a safe and constant environment. 27. Why ionization enthalphy decrases down the group with the increase in atomic size in group 18? Ans: From left to right across a period of elements, electronegativity increases. If the valence shell of an atom is less than half full, it requires less energy to lose an electron than to gain one. Conversely, if the valence shell is more than half full, it is easier to pull an electron into the valence shell than to donate one.
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