Chemistry XII Viva Notes

Qa.1 What is salt? What are its two parts?

Ans. Salt is the neutralized product of acid and base. The two essential parts are acidic radical (Anion) and Basic radical (cation).

Qs.2 What is meant by “ion”?

Ans. Ion is an atom with positive or negative change or charges.

Qs.3 What is meant by radical?

Ans. Charged atom or group of atoms. Which exists as a single unit in crystal or in solution form is known as a radical.

Qs.4 What is Acid radical?

Ans. The radical which is contributed by an acid during salt formation and having a negative charge is called acid radical (Anion).

Qs.5 What is basic radical?

Ans. The radical which is contributed by a base during salt formation and having a positive charge is called basic radical (cation).

Qs.6 Why positive radical is called cation?

Ans. On passing the current through a solution it moves towards cathode

Qs.7 Why negative radical is called Anion?

Ans. Negative ions moves towards anode during electrolysis hence they are called Anion.

Qs.8 How the formation of cation and Anion takes place fron an atom?

Ans. When an electron is removed from an atom cation is formed on the other hand when atom gains an electron Anion is formed.

X→ X+ + e- and X + e- X-

Cation Anion

Qs.9 What is meant by group reagent?

Ans. It is the reagent or chemical, used to find out a particular group of cations or Anions.

Qs.10 How many groups are there for Anion?

Ans. There are three main group for Anion.

Qs.11 How many groups are there for cation?

Ans. There are six group for cation.

Qs.12 What are the group reagents for I, II & III group of cation?

Ans. The group reagent for I group is Hcl, Hcl + H2S for II group and NH4Cl +NH4OH are the group reagent for III group.

Qs.13 What are the group reagent for I, II and III of Anion?

Ans. For I group H2SO4 or HCl (dilute) is a group reagent for II groups H2SO4 while III group gives precipitation by Bacl2 or Ammonium molyblate (NH4)2 MoO4.

Qs.14 How the cations of group I, II & III group of Anion?

Ans. The cations of group 1st are precipitated as chlorides, cations of the group at once, hence they are analysised individually e.g.BaCl2 for SO4 2-.

Qs.15 How the cations of group VI are precipitated?

Ans. There is no any specific reagent to precipitate all the cations of the group at once, hence they are analysised individually e.g. BaCl2 for SO4 2-.

Qs.16 What is difference between an “atom” “molecule” and “ion”?

Ans. Atom is the smallest part of an element which can take part in ordinary types of chemical changes. It is electrically neutral because it carries equal number of electrons & protons i.e. two particles of apposite charges. Symbol “Cl” represents a chlorine atom. Molecule is the smallest unit quantity of matter which can exist by itself and contain all the properties of the original substance. A molecule may consists of two similar atoms or two dissimilar atoms. Formula of chlorine “Cl2” represents a chlorine molecule of similar atoms and “NaCl” molecules with two dissimilar atom. Ion It is a charged form of an atom or group of atoms. It carries either a negative or a positive charge according as the number of electrons is greater or lesser than the number of protons present in it. Symbol of chlorine “Cl” represents a negatively charged chlorine atom (Anion) “Cl” while symbol of Ammonium NH4 represents an ammonium ion (cation) “(NH4+)”.

Qs.17 What is the group reagent for cation in group II?

Ans. Hydrogen Sulphate (H2S) in presence of Hydrochloric acid (HCl)

Qs.18 What is Nessler’s reagent and what for its used?

Ans. It is alkaline solution of potassium mercuric iodide K2 (Hgl4). It gives brown precipitation with ammonium salts.

Qs.19 What is chromyl chloride test?

Ans. When solid chloride is heated with potassium dichromate and Conc. Sulphate acid it gives red vapours of chromyl chloride CrO2Cl2.

Qs.20 Which chlorides are in soluble in water?

Ans. AgCl, PbCL2 and Hg2Cl2 salts are in soluble in waters.

Qs.21 What is solubility product?

Ans. It is the product of ionic conc, of the saturated solution of a salt. The Conc, is expressed in moles per liter of the ions.

Qs.22 What do you mean by qualitative analysis?

Ans. It is the process by which the components of a substance or a mixture can be detected

Qs.23 What do you mean by qualitative inorganic analysis?

Ans. It is the process by which the constituent ions of an inorganic Salt can be detected.

Qs.24 What are double salts?

Ans. Those salts whose crystals contain two salts are commonly known as double salts e.g. FeSO4 (NH4)2 SO4. 6H2O

Qs.25 What are complex salts?

Ans. The salts contains a complex cation or Anion in which a transition metal ion has coordinated with a number of electron pair donor e.g. [Fe (CN)6].

Qs.26 What is precipitate (ppt.)?

Ans. It is a compound which separates out in the solid phase from the solution phase on adding a reagent.

Qs.27 Is it possible to use “NaCl” instead of dilute HCl?

Ans. Yes, any soluble chloride can precipitate the radicals of the first group as chloride in cation. The advantage with Hcl is that it does not allow to introduce another basic radical in the solution.

Q.28 Why water and HCl are preferred for the preparation of the original solution (O.S) in the detection of basic radical?

Ans. Because no interference is caused by H2O and HCl while other acids like HNO3 and H2SO4 interfere e.g. Cation like pb2+ , Ca2+ , Sr2+ and Ba2+ form in soluble sulphates with H2SO4 and HNO3 being oxidizing agent interferes in the second groups by oxidizing H2S to S.

Qs.29 What fruity smell indicates?

Ans. The fruity smell is generally due to the formation of an ester. Which indicates the presence of CH3COO ion due to the formation of ethyl acetate CH3COO2H5 or mixed ester fruity smell obtained.

Qs.30 What is meant by water of crystallization give few examples of some compounds?

Ans. The water of crystallization is the molecule of water present in a compound e.g. Copper Sulphate CuSo4 . 5H2O. Magnesium sulphate MgSO4 . 7H2O Barium Chloride Bacl2 . 2H2O etc.

Qs.31 What is functional group?

Ans. It is a group of atoms responsible for their specific properties to the compound possessing it e.g.

i) Carbonyl group > C=O ii) Carboxylic acid group―COOH

iii) Hydroxyl group – OH iv) Amino group – NH2 etc.

Qs.32 What is vinegar?

Ans. Vinegar is a dilute solution of acetic acid. By the smell of which CH2COO- (acetate) ion is confirmed.

Qs.33 Why is testing Cl- radical, When a rod dipped in NH4OH is held over the mouth of test tube, a dense white fumes are produced?

Ans. Because chloride with conc. H2SO4 produce HCl gas which forms white fumes of NH4Cl with NH4OH.

2Cl- + H2SO4 → 2HCl + SO42-

HCl + NH4OH → NH4Cl + H2O




Qs.34 During testing of 2nd group of acidic radicals a brown gas may evolve, which may be due to Br radical or due to NO3 –radical, how will you distinguish them?

Ans. If evolved gas becomes denser on adding MnO2 then it is Br2 gas if it increased by adding copper turnings then it is NO2 gas.

Qs.35 Why in the ring test for Nitrate, a brown ring is formed at the junction of two liquid layers?

Ans. The H2SO4 decompose NO3- radical and evolves “NO” which makes a complex nitro ferrous compound with FeSo4 at the junction which appears as a brown ring.

Qs.36 Why it is necessary to prepare the original solution (O.S) of the salt for the detection of basic radicals except NH4+ radical?

Ans. All the basic radicals are metallic ions except NH4+ therefore they cannot form a volatile substance which can be detected by evolution of a gas by a particular smell. Hence they are detected only by precipitation method from their solution.

Qs.37 Why NH4+ radical can be detected, directly from its salt?

Ans. On testing with an alkali, like NaOH it evolves NH3 gas the smell of which confirms the NH4 radical.

NH4+ + NaOH → NH3 + H2O + Na+

Qs.38 Why the basic radicals are divided into six groups?

Ans. Actually they are divided on the basis of solubility product of their corresponding compounds.

Qs.39 If original solution is prepared in HCl, Why it is concluded that 1st group of basic radicals is absent?

Ans. The first group radicals from in soluble chlorides with HCl, Hence if the solution is clear in HCl it means that 1st group radicals are absent.

Qs.40 Why the ppt of AgCl is soluble in NH4OH?

Ans. Because AgCl is insoluble in water but in the presence of NH4OH it forms a complex diamine compound which can be dissolved easily in water.

Qs.41 What are brisk effervescence?

Ans. Brisk effervescence is due to the evolution of CO2 gas.

Qs.42 How does lime water turn milky on passing CO2 gas through it?

Ans. Lime water turns milky due to the formation of in soluble CaCo3.

Qs.43 What is lime water?

Ans. It is a solution of Ca(OH)2-.

Qs.44 What is slaked lime?

Ans. It is Ca(OH)2-.

Qs.45 What is lime?

Ans. It is calcium oxide CaO.

Qs.46 What is red gas?

Ans. Chromyl chloride is called red gas CrO2Cl2.

Qs.47 What violet vapours indicate?

Ans. They indicate the presence of Iodine.

Qs.48 Mention some cations with their characteristics flames?

Ans. Cations Colour of the flame

Ca2+ Brick red

Sr2+ Deep red

Ba2+ Grassy green

Cu2+ Bluish green

Qs.49 What are crystalline and amorphous salt?

Ans. The salt containing crystals are known as crystalline while powder like salts are called amorphous.

Qs.50 If the salt is coloured what cations may be present?

Ans. If the salt is coloured the following cations may be present

e.g. Cu2+, CO2+, Fe2+, Nl2+, Mn2+ and Fe3+ etc

Qs.51 Give the name of a non-metallic basic radical?

Ans. The non-metallic basic radical is Ammonium NH4+ radical.

Qs.52 In the preparation of original solution for cation. Why H2SO4 is never used?

Ans. Because it is oxidizing agent and precipitate various cation In different groups e.g. Ba2+, Sr2+ and pb2+ are precipitate as sulphate in group II. In this way the whole scheme of cation will disturbe.

Qs.53 Lead may be precipitated in group I as well in group II of cation why?

Ans. In first group PbCl2 is sparingly soluble and hence not all the lead ions Pb2+ are precipitated. Thus the remaining Pb2+ are separated out in group II as Pbs.

Qs.54 What are Alums?

Ans. Alums are the Isomorphous compound.

Qs.55 What are Isomorphous?

Ans. Compounds having the same crystal structures are known as Isomorphous compounds

Qs.56 What is potash alum?

Ans. The hydrated double sulphates salt of potassium and aluminum is known as potash alum e.g. K2SO4Al2 (SO4)3. 24H2O

Qs.57 What are the common uses of potash alum?

Ans. It is used as mordant in dyeing of fabrics sizing of paper as coagulating agent and also for cleaning of water on small scale.

Qs.58 Give the formula for some other Alums?

Ans. Ammonium iron alum (NH4)2 SO4,Fe(SO4)3 . 24H2O

Lithium chromium alum Li2SO4 .Cr2(SO4)3 . 24H2O

Soda alum Na2 SO4 . Al2(SO4)3 . 24H2O

Qs.59 What is the formula of Iodoform give its I.U.P.A.C. name?

Ans. Formula of Iodoform is CHl3 and in IUPAC its name is Tri-Iodomethane.

Qs.60 Give the formula and name of other Haloforms?

Ans. Chloroform CHCl3 and Bromoform CHBr3.

Qs.61 During the preparation of Iodoform temperature should not be higher than 80ºC Why?

Ans. Iodoform may be hydrolyzed above 80ºC.

Qs.62 What is mean by haloform reactions?

Ans. The reaction by which chloroform, bromoform and Iodoform may be prepared .

Qs.63 What is the melting point of Iodoform?

Ans. Its melting point is 119ºC.

Qs.64 What types of compounds gives haloform reactions?

Ans. The compounds like methyl ketone, acetaldehyde and ethyl alcohol can give haloform reactions.

Qs.65 What are plastics?

Ans. Plastics are the polymerized products of simple organic molecule or when two or than two simple molecules (Monomer) combine to form a big groups of polymer, it is known as plastic e.g. polythene from ethane. This is a plastic commonly known as polythene i.e.

(C2H4)n = (C2H4)n

Qs.66 What are monomers, polymers and polymerization?

Ans. A large number of simple molecules which may be combine and form a large molecule of high molecular mass are known as “Monomers”, the resulting heavy product is known as the “polymer” and the process of formation of a polymer is known as “polymerization”.

Qs.67 What is P.V.C and P.V.A?

Ans. P.V.C is only poly vinyl chloride plastic and P.V.A is poly vinyl acetate plastic.

Qs.68 What is Bakelite?

Ans. It is a plastic, which is condensation polymer of phenol and formaldehyde.

Qs.69 What is the difference between thermo-plastic & thermo-setting plastics?

Ans. “Thermo-plastics” are those which may be moulded several times by liquefaction without any chemical change e.g. poly vinyl plastic. Where as “Thermo-setting plastic” are those which may be molded once at a time of preparation and become decomposed on heating e.g. Bakelite.

Qs.70 What is the formula of phenol and formaldehyde?

Ans. Phenol is C6H5OH while formaldehyde is HCHO.

Qs.71 What is the formula of Aniline and Iodoform?

Ans. Aniline is C6H5NH2 while Iodoform is CHl3.

Qs.72 What are carbohydrates?

Ans. Carbohydrates are either polyhydroxy aldehydes or ketones or substances which on hydrolysis yield these compounds i.e. polyhydroxy aldehydes or ketones.

Qs.73 Why carbohydrates are also known as hydrates of carbon?

Ans. The general formula of carbohydrates may be Cx(H2O)y i.e. the ratio between hydrogen and oxygen is same as that in water e.g. C6H12O16 Hence they are also known as hydrates of carbon.

Qs.74 Why carbohydrates are also known as saccharides?

Ans. They are also known as saccharides because various carbohydrates gives sweet taste.

Qs.75 What are mono-saccharides?

Ans. Monosaccharides are those carbohydrates which cannot be broken into simpler substances on hydrolysis due to the reason that they consists of single unit of polyhydroxy aldehyde or ketones e.g. glucose and fructose.

Qs.76 What are disaccharides?

Ans. These carbohydrates gives two molecule of monosaccharides on hydrolysis e.g. Maltose, Lactose, and sucrose etc.

Qs.77 What are polysaccharides?

Ans. Those carbohydrates which consists of very large number of monosaccharides units are known as polysaccharides units are known as polysaccharides e.g. starch and cellulose etc.

Qs.78 What is the importance of carbohydrates in living beings?

Ans. Carbohydrates are of major importance to both plants & animals. Human beings use it for many purposes only 65 percent of carbohydrates are used in our diet. It is the chlorophyll in leaves and grass that makes them green, plants gives carbohydrates during the process of photosynthesis. Where plant take CO2 from the air and H2O from the soil and the process occur.

i.e. 6CO2 + 6H2O = C6H12O6 + 6O2

It may also used in for clothing (Cotton, Rayon, linon) and wood for building burning and making paper.

Qs.79 What are reducing sugars?

Ans. Those carbohydrates which are oxidized by Fehling’s solution and contain free aldehydic group are known as reducing sugar e.g. maltose and glucose etc.

Qs.80 What are non-reducing sugars?

Ans. Those carbohydrates which do not reduce Fehling’s solution by forming red ppt and contain no free aldehydic group are called non-reducing sugars e.g. fructose and sucrose etc.

Qs.81 What is Fehling’s solution?

Ans. It is a mixture of two solution i.e. A & B the solution “A” contains copper sulphate solution while solution “B” contain a solution of sodium potassium tatrate (alkaline medium) along with NoOH.

Qs.82 What is starch?

Ans. Starch is not a single molecule but a mixture of “Amylose” (water soluble, blue colour with iodine) and “Amylopectin” (insoluble in water, violet colour with iodine). The composition of the two is, amylose 10-20% and amylopectin 80-90%.

Qs.83 What is Benedict’s reagent?

Ans. An aqueous solution of cupric sulphate, sodium citrate and sodium carbonate is called Benedict’s reagent.

Qs.84 What is Tollen’s reagent?

Ans. Ammonical silver nitrate solution is known as Tollen’s reagent.

Qs.85 What is Roschell’s salt?

Ans. Sodium potassium tartarate is also known as Roschell’s salt. Which is used in the preparation of Fehling’s soluton.

Qs.86 What are Amino Acids?

Ans. The amino acids that occur in protein all have the – NH2 group and – COOH group attached to the same carbon atom. They are thus alpha amino acids, the carbon atom being the alpha carbon simplest formula by which it can be represent is

H

│

R ― C ― COOH

│

NH2

Qs.87 What are proteins?

Ans. The complex nitrogenous organic compound found in living cell are called proteins which on hydrolysis yield amino acids and these amino acids linked together by a peptide bond.

OR

The polymers of amino acids containing large no of amino acids joined by peptide bond is called protein

Qs.88 What is peptide bond?










O

║

Ans. The acid amide ( - C – NH - ) or the linkage through which amino acids are linked in protein is known as peptide bond.

H O H

│ ║ │

H2N ─── C ── C ─── NH ── C ── COO

│ │

R R

Pipette Bond

Qs.89 What are simple protein?

Ans. The protein on hydrolysis give only simple amino acids are simple proteins e.g. Albumin, glubuiline etc.

Qs.90 What are conjugated proteins?

Ans. Those proteins which on hydrolysis give some other compounds along with amino acids are commonly known as conjugated proteins e.g. phospholecithine

Qs.91 What is meant by derived protein?

Ans. Derived proteins are the products obtained by the action of heat, enzyme or bychemical reaction.

Qs.92 What is the effect of heat on protein and what is the effect of HNO3?

Ans. By heating it coagulates (as in egg) while it becomes yellow by the action of HNO3.

Qs.93 What are fats?

Ans. They are esters of higher fatty acids (palmatic acid, stearic acid, and oleic acid,) with glycerol and the esters are made up of an alcohol part and an acid part.

R – C – OR , C2H6O3

║

O

Acid part Alcohol part

(Mainly glycerol)

Qs.94 Why oils are formed in liquid state at ordinary temperature?

Ans. Oils are in liquid state due to the presence of unsaturated fatty acids in which one OH group of glycerol is esterified.

Qs.95 Why fats are solid at room tempertature?

Ans. Fats are solid because they contain saturated acids with glycerol.

Qs.96 What is the general formula of fats and oils?

Ans. The general formula of fat and oil is as follows.

CH2 ───── OOCR1

│

CH ───── OOCR2

│

CH2 ───── OOCR3

Facts or oil (Here R-may be same or different)

Qs.97 What is the difference between a fat and an oil?

Ans. Fat is a solid at room temperature and contains saturated fatty acids while oil is liquid and contains unsaturated fatty acids.

Qs.98 Write down the name and formula of saturated and unsaturated fatty acids found in fat & oil?

Ans. Palmatic acid C15H31 COOH saturated fattu acid.

Stearic acid C17H35 COOH saturated fatty acid.

Oleic acid C17H33 COOH saturated fatty acid.

.Qs.99 What is the formula of glycerol?

Ans. The formula is

CH2OH

│

CHOH Glycerol

│

CH2OH

Qs.100 What is Saponoifications?

Ans. Hydrolysis of fats or oil by mean of alkali is commonly known as Saponoification.

CH2 – OOC – R1 CH2 – OH ROONa

│ │ │

CH – OOC – R2 + 3NAOH → CH – OH + RCOONa

│ │ │

CH2 – OOC – R3 CH2 – OH RCOONa

Glycerine SOAP

Qs.101 What is soap?

Ans. The sodium or potassium salt of a fatty acid is called a soap e.g.

RCOONa

│

RCOONa Soap

│

RCOONa