Q24 of 47 Page 1

Answer the following :

(a) What is tincture of iodine ? What is its use ?


(b) What are the main constituents of dettol ?


(c) Label the hydrophilic and hydrophobic parts of the given


compound :


CH3(CH2)16COO(CH2CH2O)nCH2CH2OH


(a) Tincture of iodine is nothing but a weak iodine solution. It contains usually 2–7% elemental iodine, along with potassium iodide or sodium iodide, dissolved in a mixture of ethanol and water.


It is used as an antiseptic. Antiseptics are substances which stop or slow down microbial growth.


(b) The major component in Dettol which gives it the antiseptic properties arechloroxylenol(C8H9ClO) and terpineol.


Dettol is an aromatic chemical compound comprising of 4.8% of the above mixture, along with pine oil, isopropanol, castor oil, soap and water.


(c) Water hating groups that is they do not get mixed in water easily are known as hydrophobic groups, like alkyl group, whereas functional groups like alcohols, sulphonates,etc are water loving groups dissolve in water easily, hydrophilic groups.


Therefore hydrophobic part in the above detergents is the long chain alkyl group and the hydrophilic part is the alcohol group.



More from this chapter

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22

Account for the following, supporting your answer with diagrams orequations wherever possible :

(a) Diazomium salts of aromatic amines are more stable than those of aliphatic amines.


(b) Methylamine in water reacts with ferric chloride to precipitate


hydrated ferric oxide.


OR


Arrange the following in decreasing order of pKb giving reason :


(a) Aniline, p-nitroaniline and p-toluidine


(b) C2H5NH2, (C2H5)2NH, (C2H5)3N in gaseous state


 23

Answer the following with reason :

(a) Is (NH–CHR–CO)n , a homopolymer or copolymer ?


(b) Is PVC a condensation or addition polymer ?


(c) Is Bakelite a thermoplastic or a thermosetting plastic ?


 25

(a) Draw the graph between vapour pressure and temperature andexplain the elevation in boiling point of a solvent in solution.

(b) Determine the osmotic pressure of a solution prepared by


dissolving 25 mg of K2SO4 in 2 litres of water at 25°C assuming it to be completely dissociated. (Atomic masses K = 39 u, S = 32 u, O = 16 u)


OR


(a) Write two characteristics of non-ideal solution.


(b) 2 g of benzoic (C6H5COOH) dissolved in 25 g of benzene shows a depression in freezing point equal to 1.62 K. Molal depression constant for benzene is 4.9 K kg mol–1. What is the percentage association of acid if it forms dimer in solution ?


 26

Give reasons for the following :

(a) NO2 dimerises readily.


(b) Chlorine acts as a bleaching agent.


(c) In spite of small size, electron gain enthalpy of oxygen is less


negative as compared to sulphur.


(d) Unlike chlorine, fluorine forms only one oxoacid, HOF.


(e) Noble gases have very low boiling points.


OR


(a) Draw structure and name the shape of the following :


(i) SF4


(ii) ICl3


(b) What happens when (Support your answer with equation)


(i) Chlorine gas is passed through hot and concentrated sodium


hydroxidesolution ?


(ii) Xenon hexafluoride is subjected to complete hydrolysis ?


(iii) Concentrated sulphuric acid is poured over cane sugar ?