Engineering Chemistry Past Paper 2024-2025 PDF

LORDS INSTITUTE OF ENGINEERING & TECHNOLOGY UGC Autonomous Approved by AICTE | Affiliated to Osmania University Accredited by NBA | Accredited ‘A’ grade by NAA...

LORDS INSTITUTE OF ENGINEERING & TECHNOLOGY UGC Autonomous Approved by AICTE | Affiliated to Osmania University Accredited by NBA | Accredited ‘A’ grade by NAAC |Certified by ISO. Department of Science and Humanities Academic Year: 2024-25 Year: I Semester: I CIE – I -QUESTION BANK ENGINEERING CHEMISTRY [U24CH101] [Common to IT, CSM, AIML, ECE, CE & ME] Prepared by Course Coordinator: Dr. Md Sameer Ahmed, Associate Professor Course Faculties: Prof. Rehana Anjum, Associate Professor Prof. Anjum Begum, Assistant Professor Prof. Arshiya Anjum, Assistant Professor Prof. Sameera Begum, Assistant Professor Prof. G.Rahika , Assistant Professor Prof. K.Pushpalatha , Assistant Professor Note: A question bank is versatile and flexible FAQs that cover the entire syllabus of a subject. It is used by students and teachers for learning and assessment purposes only.  LORDS INSTITUTE OF ENGINEERING AND TECHNOLOGY (UGC Autonomous) Approved by AICTE/Recognized by Government of Telangana /Affiliated to Osmania University/ Accredited by NBA/Accredited with ‘A’ Grade by NAAC / Accredited by NABL B.E –I SEMESTER, CIE I QUESTION BANK, 2024-25 ENGINEERING CHEMISTRY UNIT: I ELECTROCHEMISTRY AND BATTERY CHEMISTRY SHORT ANSWER QUESTIONS CO BTL 1. Represent Quinhydrone electrode and write the electrodic reaction CO1 BTL2 for reduction process. Represent Quinhydrone electrode 2. What are Lithium-ion batteries? CO1 BTL1 Lithium–Ion Battery(LIB) Lithium ion battery is a secondary battery. Lithium ion batteries are rechargeable batteries. The primary functional components of a Li-ion battery are, Anode(-ve): Li intercalated Carbon Cathode (+ve): Lithium metal oxide (Li1-xCoO2) Electrolyte: A non-aqueous medium used as electrolyte, usually which is a mixture of organic carbonate (ethylene carbonate) containing complex ([LiPF6]) of lithium ions. Anode and cathode are separated by Electrical insulating separator (diaphragm) which permeable to lithium ions. 3. Distinguish between electrolytic and electrochemical cells. CO1 BTL2 4. What is a battery? Give one example each for primary and secondary CO1 BTL1 batteries. Battery is a device consisting of one or more electrochemical cells connected parallel or in series that converts stored chemical energy into electrical energy. Primary batteries : Eg: Zinc– Carbon battery Secondary batteries/Rechargeable batteries) : Eg: Lead- Acid battery ,Lithium ion battery. 5. Differentiate primary battery from secondary battery. CO1 BTL2 Primarybatteries Secondary batteries Rechargeable batteries) Batteries which are not rechargeable The batteries which can be recharged after their use are called are called Secondary batteries. primary batteries The chemical reactions that take place The chemical reaction that take place Are not reversible are Reversible Eg: Zinc– Carbon battery Eg:Lead- Acid battery ,Lithium ion battery. 6. Calculate the electrode potential of Zn | Zn 2+ (0.01) electrode at CO1 BTL2 0 2+ 25 c. (E Zn | Zn = 0.76 V) 0 7. Represent the Calomel electrode and writes its electrode reaction. CO1 BTL2 Calomel electrode is represented as Pt-Hg/Hg2Cl2/KCl(aq). 8. Find the EMF of the following cell CO1 BTL2 Zn / Zn+ 2(1 M)// Cu2+(1M) / Cu given E0(Zn| Zn2+ ) = 0.76 V & E0( Cu2+ / Cu) = 0.34 V 9. Calculate the electrode potential of copper electrode at 250C, if CO1 BTL2 CuSO4 = 0.001 M and E0(Cu2+ | Cu) = 0.34 V 10. Define single and standard electrode potentials. CO1 BTL1 Single Electrode potential: Tendency of an electrode to lose or gain electrons when it is in contact with its own ionic solution is called as electrode potential. The tendency of an electrode to lose electrons i.e.to get oxidized, is called Oxidation potential, whereas, the tendency of an electrode to gain electrons i.e.to get reduced, is called Reduction potential.  Standard electrode potential: “The tendency of a pure metal or pure gas at 1 atm pressure to undergo oxidation or reduction when it is in contact with 1M solution of its ions at 250C, is called as standard electrode potential. 11. Mention two half-cell reactions of methanol – oxygen fuel cell. CO1 BTL2 12. What is galvanic cell? Write its anodic and cathodic reactions. CO1 BTL2 GALVANIC CELL A device in which chemical energy is changed to electrical energy. 13. What are reversible and irreversible cells? CO1 BTL2 s.no Reversible cells Irreversible cells 1 Cell reaction reversible Cell reaction is irreversible 2 Cell reaction occurs when two Cell reaction occurs may occur when two electrodes are connected electrodes are not connected externally externally 3 It is a galvanic cell It is an electrolytic cell 14. Write half-cell and complete cell reaction for given cell notation. CO1 BTL2 Zn/Zn+ 2 // Ag+/Ag 15. Write a note on glass electrode. CO1 BTL1 The representation of glass electrode is, Ag/AgCl/0.1N HCl/Glass membrane. Thepotentialofthe glasselectrode is given as,𝐸𝐺=𝐸0−0.0591𝑝𝐻 𝐺 UNIT- II WATER CHEMISTRY AND CORROSION 16. Explain sacrificial anodic method of protecting corrosion. CO2 BTL2 In this method, the metallic structure to be protected is electrically connected to a more active or anodic metal thanthe metallic structure to be protected. The more active metal acts as anode and gets corroded slowly; while the parent structure (metallic structure to be protected)is forced to act as cathode of galvanic cell, hence protected. As this more active metal is sacrificed its life in the process of saving metallic structure from corrosion, it is known assacrificialanodeand,therefore,thismethodiscalledassacrificialanodicprotection 17. What are the specifications of potable water. CO2 BTL1 Specifications of Potable water/Drinking/Municipal water (any four) Water which is safe to drink is said to be potable water or drinking water. Potable water should have following specifications, 1. Should be sparkling clear and odorless 2. Water should be pleasant in taste. 3. Water should be perfectly cool and its turbidity should not exceed10ppm. 4. It should be free of objectionable minerals such as lead, arsenic, chromium and manganese salts. 5. pH should be around 8 6. Dissolved salts should be less than 500ppm 7. It should be free from disease–producing microorganisms. 8. Chloride,Fluoride&Sulphate contents should be less than 250ppm, 1.5ppm and250 ppm respectively 18. How does Zinc protect the Iron from corrosion? CO2 BTL2 Galvanising is a method of rust prevention. The iron or steel object is coated in a thin layer of zinc. This stops oxygen and water reaching the metal underneath – but the zinc also acts as a sacrificial metal. Zinc is more reactive than iron, so it oxidises rather than the iron object. 19. A sample of water gives an analysis 13.6 mg/L of CaSO4 , 7.3 CO2 BTL mg/L of Mg(HCO3)2. Calculate the total hardness and 2 permanent hardness. 20. Define the term “Reverse osmosis”. CO2 BTL1 REVERSEOSMOSIS: When two solutions of unequal concentration are separated by a semi-permeable membrane, flow of solvent takes place from dilute to concentration side, due to increase in osmostic pressure, which is termed as osmosis. However, when a hydrostatic pressure in excess of osmotic pressure is applied on the concentrated side,the solvent flow is reversed from concentrated side to dilute side, across the membrane. This principle is termed as reverse osmosis 21. A Sample of hard water contains the following dissolved salts CO2 BTL per litre. CaCl2 = 111 mgs, CaSO4 = 1.36 mgs, Ca(HCO3)2 = 16.2 2 mgs, Mg(HCO3)2 = 14.6 mgs, Silica = 40 gms, Turbidity = 10 mgs. Calculate the temporary, permanent and total hardness of water in ppm 22. Explain the significance of Break Point Chlorination. CO3 BTL1 Significance Involves in addition of sufficient amt. of chlorine to oxidise :organic matter, reducing substances. Dosage of applied chlorine to water rich inorganic compound or ammonia is gradually increased. All tastes, odour disappear at breakpoint water free from bad tastes and odours 23. Explain the principle of cathodic reaction of corrosion. CO3 BTL2 Catholic protection: The principle involved in this method is to force the metal to be protected (Parent metal) to behave like cathode. Therefore, corrosion of the parent metal is prevented. There are two types of cathodic protections, (a)Sacrificial anodic protection (b)Impressed current cathodic protection. 24. When copper is in contact with Iron what will be corroded and why? CO3 BTL2 When copper comes in contact with iron, it makes the process of rusting faster. This is because copper has higher reduction potential than iron, and makes the oxidation of iron faster hence rusting 25. 50 ml of sample water consumed 20 ml of 0.01 M EDTA before CO2 BTL3 boiling and 5 ml of the same EDTA after boiling. Calculate the total, permanent and temporary hardness. 26 What is hardness of water? Write its unit. CO3 BTL2  Hardness of Water: Hardness of water is “the characteristic that prevents lathering of soap”.(Or)It is defined as“ the soap consuming capacity of water”. Units of hardness: Parts per million(ppm Milligrams per litre (mg/L) Clarke’s degree(°Cl): Degree French(°Fr): Relationship betweenvariousunitsof hardness: 1ppm=1mg/L=0.1°Fr=0.07°Cl;1mg/L= 1ppm= 0.1°Fr=0.07°Cl; 27. How can the cation and anion exchanger can be regenerated? CO3 BTL2 REGENERATION OF RESINS: 28. What is the electroless nickel plating process? CO3 BTL2 Electroless Nickel Plating (ENP) is the deposit of a nickel -alloy coating by chemical reduction – without the electric current that’s used in electroplating processes. The majority of ENP for engineering purposes is a nickel phosphorus deposit containing 2 to 14% phosphorus. The higher the phosphorus content the greater the corrosion resistance, however the compromise on increased phosphorus content is a decrease in hardness. 29. What do you mean by break point chlorination? CO2 BTL1  Involves in addition of sufficient amt. of chlorine to oxidise :organic matter, reducing substances. Dosage of applied chlorine to water rich inorganic compound or ammonia is gradually increased. All tastes, odour disappear at breakpoint water free from bad tastes and odours 30. Calculate the total hardness of 1000 litre of a water sample CO2 BTL containing the following impurities:16.2 mg/L -Ca(HCO3) 2, 11.1 3 mg/L -CaCl2, 60 mg/L - MgSo4 & 19 mg/L - MgCl2 UNIT: III ENGINEERIN GMATERIALS 31. What is Polymer? Give an example. CO4 BTL1 Polymers are high molecular weight giant molecules formed by linking together of small molecules, monomers, by means of covalent bond/chemical bond. Examples: poly ethylene, poly (vinyl chloride), Bakelite, etc.. 32 Define degree of polymerization. Number of monomers/repeat units present in the polymer is called “Degree of polymerization”. Example 33 Write the properties and applications of PVC. CO4 BTL2 Properties Rigid PVC is a colourless, odourless and non-inflammable. 2. It has excellent oil resistance and resistance to weathering. Applications 1. Leather cloth used for car seat, covers etc 2. Kitchen upholstery, ladies hand bags, plastic rain coats 3. Baby pants, swim suits etc. 34. Distinguish between addition polymerization from condensation CO4 BTL2 polymerization  Addition polymerization/Chain growth polymerization: ✓ Addition polymerization is a reaction that yields a polymer which is an exact multiple of monomers, without the elimination of by-products. ✓ Monomers having double bonds such as alkenes, alkynes, undergo addition polymerization. Condensation polymerization/step polymerization: ✓ Condensation polymerization is a reaction occurring between two bi – or poly functional monomers having polar functional groups. ✓ It always accompanies with elimination of small molecules like H2O, HCl, NH3, etc. ✓ For example, >C=O, -COOH, -OH and –NH2 carrying monomers undergo condensation polymerization. 35 Distinguish between homo polymer and co – polymer. CO4 BTL2 Homo polymers: The polymers which are made up of identical monomer units are called as homo polymer. ….−M−M−M−M−M−M−M−…… Examples: polythene, polystyrene, poly (vinyl chloride), etc. ✓ Co-polymers: The polymers which are made up of different monomers are known as co-polymers. Examples: Buna-S, etc. 36 What is the requirement for a simple organic compound to function CO4 BTL2 as a monomer? The small molecules to act as a monomer, their functionality should be at least two it must have at least one double bond or functional groups 37. Define monomer and its functionality. Monomers: The small individual molecules which combine with each other to form large molecules are called monomers. Examples: Ethylene, vinyl chloride, styrene, etc. Functionality of Monomer: “The Number of bonding sites present in a monomer” is called functionality of monomer NameofMono Structure Functiona mer lity Ethene CH2=CH2 2 1,3-butadiene CH2=CH- 2 CH=CH2  UNIT: I ELECTROCHEMISTRY AND BATTERY CHEMISTRY LONG ANSWER QUESTIONS BTL CO 38. a) Write the cell reaction and calculate the emf of the cell at 25o C. CO1 BTL3 Zn / Zn+ 2 // Fe+3 / Fe2+/ Pt (0.01M) (0.1M) (E0Zn/Zn2+ = 0.76V) and (E0 Fe3+/ Fe2+ = 0.77V) 39. Explain how pH is determined using quinhydrone electrode. CO1 BTL3 Quinhydrone Electrode: Construction and working of Quinhydrone electrode: The Quinhydrone electrode is an example of redox electrode, which is constructed by adding a pinch of Quinhydrone powder, which is an equimolar mixture of quinone and hydroquinone to a acid solution, under test, taken in a beaker. An inert Pt electrode is dipped into the solution for making electrical contact.The electrode is represented a H+; Q QH/Pt.(aq) 2 It will either act as anode or cathode depending on the other electrode to which it is connected.  The electrode potential of Quinhydrone electrode, which is reversible to H+ ions, depends on pH of a solution; therefore it is used to determine pH of a solution. To determine pH of a solution, quinhydrone electrode is combined with a referenceelectrodelikecalomelelectrode.ThecellconsistsofQuinhydroneandCalomelelect rodeisrepresentedas, Pt, Hg/ Hg2Cl2,Cl-(Sat ,aq)// H+(aq),Q,QH2/Pt. 𝐸𝑐𝑒𝑙𝑙=0.457−0.0591𝑝𝐻 0.457−𝐸𝑐𝑒𝑙𝑙 𝑝𝐻= 0.0591 40. For a cell Zn(s)/Zn2+(0.01M // H+(0.01M) /Pt|H2(1atm), calculate CO1 BTL3 emf of the cell if standard electrode potentials of Zinc electrode and Hydrogen electrode are +0.76V and 0.00V respectively. 41 Differentiate between CO1 BTL2 a) Primary battery, secondary battery and fuel cell with examples. b) Electrolytic cell from electrochemical cell. 42. What are reference electrodes? Describe the construction, working CO1 BTL3 and applications of calomel electrode? A reference electrode is an electrode that has a stable and well- known electrode potential.. It serves as a standard point of reference to determine the electrochemical potential of other electrodes in a system. Example of reference electrodes : Saturated Calomel Electrode (SCE) Standard Hydrogen Electrode (SHE) Saturated Calomel electrode: It consists of mercury at the bottom over which a paste of mercury mercurous chloride is placed. A solution of potassium chloride is then placed over the paste. A platinum wire sealed in a glass tube helps in making the electrical contact. The electrode is connected with the help of the side tube on the left through a salt bridge with the other electrode to make a complete cell. The electrode is represented as Pt, Hg/ Hg2Cl2, Cl- (aq) The potential of the calomel electrode depends upon the concentration of the potassium chloride solution. 43. Write the electrode representation and electrode reaction for the CO1 BTL3 reduction process of Calomel electrode calomel electrode: It consists of mercury at the bottom over which a paste of mercury mercurous chloride is placed. A solution of potassium chloride is then placed over the paste. A platinum wire sealed in a glass tube helps in making the electrical contact. The electrode is connected with the help of the side tube on the left through a salt bridge with the other electrode to make a complete cell. The electrode is represented as Pt, Hg/ Hg2Cl2, Cl- (aq) The potential of the  calomel electrode depends upon the concentration of the potassium chloride solution. 44. a) What is secondary battery? Describe the construction working and CO1 BTL3 applications of Lead acid battery 45. What is Lithium-ion batteries? Explain their advantages and CO1 BTL2 applications. Lithium–IonBattery(LIB) Lithium ion battery is a secondary battery. Lithium ion batteries are rechargeable batteries. Construction The primary functional components of a Li-ion battery are, Anode(-ve): Li intercalated Carbon Cathode (+ve): Lithium metal oxide (Li1-xCoO2) Electrolyte: A non-aqueous medium used aselectrolyte,usually which is a mixture of organic carbonate (ethylene carbonate) containing complex ([LiPF6])of lithium ions. Anode and cathode are separated by Electrical insulating separator (diaphragm) which permeable to lithium ions. 46 What is reference electrode? Give two examples and represent them and write their electrode reaction for reduction process. 47. Write the electrode representation and electrode reaction for the CO1 BTL3 reduction process of Quinhydrone electrode QuinhydroneElectrode: Construction and working of Quinhydrone electrode: The Quinhydrone electrode is an example of redox electrode, which is constructed by adding a pinch of Quinhydrone powder, which is an equimolar mixture of quinine and hydroquinone to a acid solution, under test,taken in a beaker. An inert Pt electrode is dipped into the solution form eletrical contact. The electrode is represented as H+; Q; QH/Pt. (aq) 2 Itwilleitheractasanodeorcathodedependingontheotherelectrodetowhichitisconnected.  Determination of Ph of a solution using quinhydrone electrode: The electrode potential of Quinhydrone electrode, which is reversible to H+ ions, depends on pH of a solution; therefore it is used to determine pH of a solution. To determine pH of a solution, quinhydrone electrode is combined with a referenceelectrodelikecalomelelectrode.ThecellconsistsofQuinhydroneandCalomelelect rodeisrepresentedas, Pt, Hg/ Hg2Cl2,Cl-(Sat ,aq)// H+(aq),Q,QH2/Pt. 𝐸𝑐𝑒𝑙𝑙=0.457−0.0591𝑝𝐻 0.457−𝐸𝑐𝑒𝑙𝑙 𝑝𝐻= 0.0591 48. Write the cell reaction and calculate the EMF of the cell CO1 BTL3 H2 (1 atm) / H+ (0.01 M)// Cu2+ (0.1 M)/Cu where electrode potential of copper and hydrogen electrode is 0.34 v & 0.00 v respectively 49 b) Determine the EMF of the following cell at 250C with the help of Nernst equation by finding the net reaction. Mg | Mg2+ (0.01 M) || Cu2+ (0.1M) | Cu E0(Mg2+ | Mg ) = - 2.364V & E0( Cu |Cu2+) = - 0.334 V 50. a) Differentiate between primary, secondary and fuel cell. CO1 BTL3 51 List down the applications of calomel electrode and Nernst equation. Applications of Nernst Equation: 1. Nernstequationisusedtostudytheeffectof electrolyteconcentrationonelectrodepote ntial. 2. Nernstequationcanbeusedtocalculatecell potentials/Electrodepotentialsundernon- standardandnon-equilibriumcondition. 3. Determinationofunknownconcentrationo foneoftheionicspeciesinvolvedinaredoxre actionispossiblewithhelpofNernstequatio nprovided𝐸0 and Concentration of other ionic species is known.  SCE Applications The SCE is used in pH measurement, cyclic voltammetry and general aqueous electrochemistry. This electrode and the silver/silver chloride reference electrode work in the same way. In both electrodes, the activity of the metal ion is fixed by the solubility of the metal salt. The calomel electrode contains mercury, which poses much greater health hazards than the silver metal used in the Ag/AgCl electrode. 52 What is secondary battery? Explain in detail construction, working CO1 BTL3 and applications of lead-acid battery. Secondary batteries are those batteries which can be recharged by passing electric current through them and hence can be used over again e.g., lead storage battery.  UNIT- II WATER CHEMISTRY AND CORROSION 53. Explain principle and method of determination of hardness of water CO2 BTL3 by EDTA method. I. Principle: Hardness of water is estimated by a complexometric titration which involvesEDTA(EtheleneDiamineAceticAcid)asacomplexingagent.EDTAf orms1:1stable,colourlesscomplexeswithCa+2/Mg+2 ionsatpH =9-10. In this titration, Eriochrome Black-T (EBT) is used as indicator which shows blue colour in itsfree state. When EBT is added to Hard water sample buffered to pH = 10, the water sampleturnstowine- redcolourduetotheformationofunstable[Ca-EBT]/[Mg-EBT] complex. During titration, EDTA first combines with freely available Ca+2/ Mg +2 ions of sample water to form stable and colourless [Ca-EDTA]/[Mg-EDTA] complex and when all freely available Ca +2/ Mg +2 ions are complexed with EDTA; further added EDTA displaces EBT from [Ca-EBT/Mg- EBT]complex.Thus,attheendpointthecolourofthesolutionchangesfromwineredtoblue. Formulae for Estimation of Hardness of Water byOFEDTA STEP 1 - PREPARATION Method STANDARD HARD WATER Molarity(M1) of Standard Hard H2O STEP 2=– STANDARDIZATION OF EDTA solution M1= Molarity of standard Molarity of EDTA solution (M2): V 1 M1 = wt. of CaCO3 x 1000 =hard----- M water V 2 M2 M2 = V1 = Volume of standard n1 hard water V 1M 1 = n2 M2= Molarity of EDTA M V2= Volume of EDTA V2 n1 & n2 are no. of moles +2 +2 of Ca / Mg & EDTA = 1 each STEP 3 –ESTIMATION OF TOTAL HARDNESS OF WATER M = Molarity of EDTA Molarity of Hard water 2 sample (M3): M3 = V2= Volume of EDTA V2M2 = VV 3=2M volume of Hard 2 = V3M3 4 - Permanentwater STEPM n2 samplenOf Hardness 3 M3= Molarity of Water : V M 2= Molarity Hard of EDTA water sample M = 4 V2M2 Vn23=&Volume =n2 are no. V4 of of EDTA 3 V2M2 = M4 Vmoles 4 = volume of Ca +2 of / +2 Hard Mg & EDTA water = 1 each sample AFTER M n2 BOILING n4 V M4= Molarity of Hard water sample 4 AFTER BOILING n4& n2 are no. of +2 moles of Ca / +2 Mg and EDTA = 1 each  Total Hardness Of Water Permanent =Hardness M3 X 100Of the Water X1000Sample =M mg/L or 4 x 100 x 1000 ppm ppm Temporary Hardness Of the Water Sample = (Total Hardness – Permanent Hardness) = (M3 x 100 x1000 – M4 x 100 x1000) ppm 54. Calculate temporary and permanent hardness in the following water CO2 BTL2 sample containing Ca(HCO3)2 = 10.5 ppm ,Mg(HCO3)2 = 12.5 ppm, CaSO4 = 7.5 ppm, CaCl2 = 8.2 ppm, MgSO4 = 2.6 ppm. 55. Explain Ion – exchange method for softening of water CO2 BTL3 Softening of water by ionexchange method: This method is also known as de- mineralization process. Principle: When a sample of water containing different salts (Electrolytes) come in contact with anion-exchange resin,the ions of same sign are exchanged between the resin and the water sample. The ion-exchange resins are insoluble, porous; cross linked polymeric materials (generally these areco-polymers of styrene and di-vinyl benzene). The functional groups attached to the chains of the polymers are responsible for ion-exchange properties. Ion exchange resins are of two types; 1. Cation exchange resins:  It consists of fixed anions(SO–,COO-3) and exchangeable cations (H+ions). 2. Anionexchangeresins: Itconsistsoffixedcations (N+R3 ION EXCHANGE PROCESS/DETERMINERALISATION PROCESS: Ion exchange resins are insoluble, cross-linked, long chain organic polymers. The functional groups attached to the chains can exchange hardness producing cat-ions and an-ions present in the water PROCESS: The process involves the following steps: 1) The first chamber is packed with cat-ion exchange resin (RH+). When the hard water is passed through a bed of cation exchange resin it exchanges H+ with Ca+, Mg+2, K+, Na+ etc of hard water. + 2+ 2+ + - 2RH + Mg Cl2à R2Mg + 2H Cl + 2+ 2+ + - 2RH + Ca Cl2 à R2Ca + 2H Cl + 2+ +2 + - 2RH + CaSO4 à R2Ca + 2H + SO4  2+ Thus, the hardness producing cations (Ca , 2+ Mg etc) are removed 1) The second chamber is packed with anion exchange resin. The water coming + - out of the first chamber contains H , Cl , 2 - SO4 - and HCO3 ions. It is now passed through anion exchange resin bed which - can exchange OH ions with anions like 2- - Cl-, SO4 and HCO3 l - l - R OH + Cl à R Cl + OH l 2R OH + 2 SO4 - 56 à l R 2S 2- O4 + 2OH - l RO  + 3) Thus, H ions produced from first chamber - combine with OH ions produced from second chamber to form water. + - H + OH à H2O Hence, the water produced from ion-exchange process is completely free from all cations and anions of salts. Regeneration of resins: When resins get saturated they need to be regenerated. The cation exchange resin is regenerated by using dil. HCl, where as anion exchange resin is regenerated by dil. NaOH. Advantages: 1. This method is capable reducing hardness to almost zero. 2. It can be used to soften acidic/alkaline water. Disadvantages: 1. This method is expensive. 2. It can’t remove organic impurities and colloidal impurities. What is Chlorination? Explain different methods of chlorination? CO2 BTL 2 Chlorination : The process of killing pathogenic bacteria and other micro-organisms by adding cholrine is called‘Disinfection or Sterilisation’ by chlorination. The chemicals used for killing bacteria are called ‘DISINFECTANTS’. METHODS OF CHLORINATION: A) By adding Cl2: Clorine gas added to water.it form hypochlorous acid. HOCl is a powerful disinfectant Cl2 + H2O --→HOCl (Hypo Chlorous Acid) + HCl Germs + HOCl ---→ Germs are killed B) By adding Chloramines When chlorine and ammonia are mixed in the ratio 2:1, a compound called Chloramine is formed.  Cl2 + NH3 -----→ ClNH2 + HCl ClNH2 + H2O -----→ HOCl + NH3 Germs + HOCl à Germs are killed By adding Bleaching Powder: Water is mixed with required amount of bleaching powder, and the mixture is allowed to stand for several hours CaOCl2 + H2O ---→ Ca(OH)2 + Cl2 Cl2 + H2O -----→ HOCl (Hypo Chlorous Acid) + HCl Germs + HOCl ----→Germs are killed The disinfection action of bleaching powder is due to available chlorine in it. It forms hypochlorous acid which act as a powerful germicide (disinfectant) 57. What is hardness of water? Describe the complexometric method CO2 BTL3 using EDTA for the determination of hardness of water. Hardness of Water: Hardness of water is “the characteristic that prevents lathering of soap”. (Or) Itisdefined as “the soap consuming capacity of water”. Cause of Hardness: Hardness of water is caused by the presence of certain soluble salts of Ca, Mg,and salts of some other heavy metals I. Principle: Hardness of water is estimated by a complexometric titration which involves EDTA (Ethelene Diamine Acetic Acid) as a complexing agent. EDTA forms 1:1 stable, colourless complexes with Ca+2/Mg+2 ions at pH = 9 -10. In this titration, Eriochrome Black-T (EBT) is used as indicator which shows blue colour in its free state. When EBT is added to Hard water sample buffered to pH = 10, the water sample turns to wine-red colour due to the formation of unstable [Ca-EBT]/[Mg-EBT] complex. During titration, EDTA first combines with freely available Ca +2/ Mg +2 ions of sample water to form stable and colourless [Ca-EDTA]/[Mg-EDTA] complex and when all freely available Ca +2 / Mg +2 ions are complexed with EDTA; further added EDTA displaces EBT from [Ca- EBT/Mg- EBT] complex. Thus, at the end point the colour of the solution changes from winered to blue. Formulae for Estimation of Hardness of Water byOFEDTA STEP 1 - PREPARATION Method STANDARD HARD WATER Molarity(M1) of Standard Hard H2O STEP 2=– STANDARDIZATION OF EDTA solution M1= Molarity of standard Molarity of EDTA solution (M2): V 1 M1 = wt. of CaCO3 x 1000 =hard----- M water V 2 M2 M2 = V1 = Volume of standard n1 hard water V 1M 1 = n2 M2= Molarity of EDTA M V2= Volume of EDTA V2 n1 & n2 are no. of moles +2 +2 of Ca / Mg & EDTA = 1 each STEP 3 –ESTIMATION OF TOTAL HARDNESS OF WATER M = Molarity of EDTA Molarity of Hard water 2 sample (M3): M3 = V2= Volume of EDTA V2M2 = VV 3=2M volume of Hard 2 = V3M3 4 - Permanentwater STEPM n2 samplenOf Hardness 3 M3= Molarity of Water : V M 2= Molarity Hard of EDTA water sample M = 4 V2M2 Vn23=&Volume =n2 are no. V4 of of EDTA 3 V2M2 = M4 Vmoles 4 = volume of Ca +2 of / +2 Hard Mg & EDTA water = 1 each sample AFTER M n2 BOILING n4 V M4= Molarity of Hard water sample 4 AFTER BOILING n4& n2 are no. of +2 moles of Ca / +2 Mg and EDTA = 1 each  Total Hardness Of Water Permanent =Hardness M3 X 100Of the Water X1000Sample =M mg/L or 4 x 100 x 1000 ppm ppm Temporary Hardness Of the Water Sample = (Total Hardness – Permanent Hardness) = (M3 x 100 x1000 – M4 x 100 x1000) ppm 58. What is corrosion of metals? Describe the mechanism of CO3 BTL3 electrochemical corrosion by a) Hydrogen evolution and b) Oxygen absorption Corrosion of Metals: Corrosion is a process of gradual deterioration or destruction of metals or alloys from its surfacedueto unwanted chemical or electrochemical interaction of metal with its environment. Examples: 1. Formation of a layer of reddish brown scale of hydrated ferric oxide on the surface of iron.Formation of a green film of basic carbonate [CuCO3+Cu (OH)2] on the surface of Copper Wet or Electrochemical corrosion: Wet or electro chemical corrosion is common type of corrosion which occurs under wet ormoist conditions. It is observed when (i) a metal is in contact with a conducting liquid , and/or (ii) dissimilarmetals are dipped partially in aqueous corrosive environment. 59. What is the principle involved in Cathodic protection? Discuss the CO3 BTL3 two types of cathodic protection. Cathodic protection: The principle involved in this method is to force the metal to be protected (Parent metal) to behave like cathode. Therefore, corrosion of the parent metal is prevented. There are two types of cathodic protections, (a) Sacrificial anodic protection (b) Impressed current cathodic protection. sacrificial anode method In this method, the metallic structure to be protected is electrically connected to a more active or anodic metal than the metallic structure to be protected. The more active metal acts as anode and gets corroded slowly; while the parent structure (metallic structure to be protected) is forced to act as cathode of galvanic cell, hence protected. As this more active metal is sacrificed its life in the process of saving metallic structure from corrosion, it is known as sacrificial anode and, therefore, thismethod is called as sacrificial anodic protection  a) Impressed current cathodic protection In this method, an impressed D.C current is applied, through D.C current source by a battery, between the metallic structure to be protected which is forced to act as cathode and an insoluble electrode like platinum, graphite or nickel which is buried in conducting medium adjacent to the metallic structure to be protected and acts as anode of an electrolytic cell as shown in the figure. The impressed D.C current applied nullifies the corrosion current thus the metallic structure is protected from corrosion. The metals which are commonly used as insoluble anodes are Graphite, Scrap iron, etc.This type of cathodic protection is applied to buried structures such as tanks and pipelines, since, their operating and maintenance costs are less, and they are well suited for large structures and long term operations..60 What are the disadvantages of hard water? Explain the methods of CO2 BTL3 removal of hardness of water by Ion – Exchange method. a) DISADVANTAGES OF HARDWATER / CAUSES OF HARDNESS: The following are the disadvantages when hard water is used for various purpose: (i) DOMESTIC USE: (a) Washing and Bathing : Hard water does not form lather easily with soap is wasted (b) Drinking : Hard water causes bad effects on our digestive system. Sometimes, stone formation takes place in kidneys (c) Cooking : The boiling point of water is increased due to the presence of salts. Hence, more fuel and timeare required for cooking. (c) Textile Industry : Hard water causes wastage of soap. Precipitates of calcium and magnesiumsoap adhere to the fabrics and cause problem (d) Paper Industry : Calcium and Magnesium salts in water may effect the quality of paper. (e) Sugar Industry : Water containing sulphates, carbonates, nitrates (f) affects the crystallisation of sugar. Softening of water by ion exchange method: This method is also known as de- mineralization process. Principle: When a sample of water containing different salts (Electrolytes) come in contact with anion-exchange resin, the ions of same sign are exchanged between the resin and the water sample. The ion-exchange resins are insoluble, porous; cross linked polymeric materials (generally these are co-polymers of styrene and di-vinyl benzene). The functional groups attached to the chains of the polymers are responsible for ion-exchange properties. Ion exchange resins are of two types; 3. Cation exchange resins: It consists of fixed anions (SO3–,COO-)and exchangeable cations (H+ions). 4. Anion exchange resins: Itconsistsoffixedcations (N+R3 ION EXCHANGE PROCESS/DETERMINERALISATION PROCESS: Ion exchange resins are insoluble, cross-linked, long chain organic polymers. The functional groups attached to the chains can exchange hardness producing cat-ions and an-ions present in the water PROCESS: The process involves the following steps: 1) The first chamber is packed with cat- ion exchange resin (RH+). When the hard water is passed through a bed of cation exchange resin it exchanges H+ with Ca+, Mg+2, K+, Na+ etc of hard water. + 2+ 2+ + - 2RH + Mg Cl2à R2Mg + 2H Cl + 2+ 2+ + - 2RH + Ca Cl2 à R2Ca + 2H Cl + 2+ +2 + - 2RH + CaSO4 à R2Ca + 2H + SO4  2+ Thus, the hardness producing cations (Ca , 2+ Mg etc) are removed 1) The second chamber is packed with anion exchange resin. The water coming + - out of the first chamber contains H , Cl , 2 - SO4 - and HCO3 ions. It is now passed through anion exchange resin bed which - can exchange OH ions with anions like 2- - Cl-, SO4 and HCO3 l - l - R OH + Cl à R Cl + OH l 2R OH + 2 SO4 - à l R 2S 2- O4 + 2OH - l RO  + 3) Thus, H ions produced from first chamber - combine with OH ions produced from second chamber to form water. + - H + OH à H2O Hence, the water produced from ion-exchange process is completely free from all cations and anions of salts. Regeneration of resins: When resins get saturated they need to be regenerated. The cation exchange resin is regenerated byusingdil. HCl, whereasanionexchange resinis regeneratedbydil. NaOH. Advantages: 3. This method is capable reducing hardness to almost zero. 4. It can be used to soften acidic/alkaline water. Disadvantages: 3. This method is expensive. 4. It can’t remove organic impurities and colloida limpurities. 62 1 gm of CaCO3 was dissolved in HCl and the solution was made CO2 BTL4 upto one litre with distilled water. 50 ml of the above solution required 30 ml of EDTA solution on titration. 50 ml of hard water sample required 40 ml of the same solution of EDTA for titration. 50 ml of the hard water after boiling, filtering etc. required 30 ml of the same EDTA solution for titration. Calculate the temporary hardness of the water Molarity of CaCO3 solution (M1) = wt. of CaCO3 x 1000 = M.Wt. of CaCO3 Vml 1 x 1000 = 0.01 M  100 Molarity of EDTA solution (M2) = V1 M1 V2 V1= volume of CaCO3 solution = 50 ml M1= Molarity of CaCO3 solution = 0.01 M V2= volume of EDTA = 30 ml M2= V1 M1 = 50 x 0.01 = 0.016 M V2 30 Molarity of Hard Water Sample (M3) = V2 M2 V3 V2= volume of EDTA = 40 ml M2= Molarity of EDTA = 0.016 M V3= volume of hard water sample = 50 ml M3= 40 x 0.016 = 0.0128 M 50 Total Hardness of water sample = M3 x 100 x 1000 = 0.0128 x 100 x 1000 = 1280 ppm Permanent hardness of water sample: V4 M4 = V2 M2 M 4 = V2 M 2 V4 V2= volume of EDTA = 30 ml M2= molarity of EDTA = 0.016 V4= volume of permanent hardness containing water = 50 M4 = 30 x 0.016 = 0.0096 M 50 Permanent hardness of water = M4 x 100 x 1000 = 0.0096 x 100 x 1000 = 960 ppm Temporary hardness = Total hardness – Permanent hardness = 1280 – 960 = 320 ppM 63 Explain reverse Osmosis method of water softening. CO3 BTL4 REVERSEOSMOSIS: When two solutions of unequal concentration are separated by a semi-permeable membrane, flow of solvent takes place from dilute to concentration side, due to increase in osmostic pressure, which is termed as osmosis. However, when a hydrostatic pressure in excess of osmotic pressure is applied on the concentrated side,the solvent flow is reversed from concentrated side to dilute side, across the membrane. This principle is termed as reverse osmosis METHOD OF PURIFICATION The reverse osmosis cell consists of a chamber fitted with a semi-permeable membrane, above which sea water/impure water is taken and a pressure of 15 to 40 kg/cm2 is applied on the sea water/impure water. The pure water is forced through the semi permeable membrane which is made of very thin films of cellulose acelate. However superior membrane made of Polymethacrylate and Polyamide polymers have come to use 64. How do the following factors influence the rate of corrosion? CO2 BTL3 a) Position in galvanic series b) Purity of metal c) Humidity in air d). Nature of surface film Nature of metal Position of the metal in Galvanic Series: Galvanic series gives real and useful information regarding the corrosion behaviour of metals and alloys in a given environment. When two metals are electrically combined and exposed to corrosive environment the metal with lower potential acts as anode and undergoes corrosion where as the metal with higher potential acts as cathode. b)Purity of metal: In general higher the purity of the metal, lesser the rate of corrosion. Thus zinc of 99.95 % purity undergoes corrosion at rate of about 5000 times more compared to zinc of 99.999% purity c)humidity in air: Higher the humidity (moisture content) higher will be the rate of corrosion. Moisture acts as solvent for O2, H2S, SO2 etc to furnish the electrolyte essential for setting corrosion cell. Gases like H2S and SO2 increase the acidity of the medium by their dissolution in water. Therefore, the rate of corrosion increases as humidity increases Nature of surface oxide film If the corrosion product formed is stable, non-porous and strongly adherent layer it prevents further corrosion. If corrosion product formed is highly unstable the metals do not undergo corrosion.  If the corrosion product formed is porous or volatile metals undergo severe corrosion. If the corrosion product is soluble in medium to which it is immersed, corrosion of the metal occurs with a faster rate 65. Calculate total and temporary hardness of water if 5 g of CaCO3 was CO2 BTL4 dissolved in dil. HCl & diluted to 1000 ml. 50 ml of this solution required 48 ml of EDTA solution for titration. 50 ml of hard water sample required 15 ml of EDTA solution for titration. 50 ml of same water sample on boiling, filtering etc. required 10 ml of EDTA solution 66. 0.5 gm of CaCO3 was dissolved 0.1m HCl and diluted to 100 ml. BTL 50ml of this solution required 48 ml of EDTA solution for titration. 4 CO2 50 m1 of same sample required 15 ml of EDTA solution. 50 ml of the same on boiling, filtering required 10 ml of EDTA solution. Calculate temporary, permanent and total hardness of water sample. 67. What are the specifications of potable water. CO2 BTL1 Specifications of Potable water/Drinking/Municipal water (any four) Water which safe to drink is said to be potable water or drinking water. Potable water should have following specifications, Should be sparkling clear and odorless Water should be pleasant in taste. Water should be perfectly cool and its turbidity should not exceed10ppm. It should be free of objectionable minerals such as lead, arsenic, chromium and manganese salts. pH should be around 8 Dissolved salts should be less than 500ppm It should be free from disease–producing microorganisms. Chloride,Fluoride&Sulphate contents should be less than 250ppm, 1.5ppm and250 ppm respectively 68 What is chlorination? Explain in detail break point chlorination. CO3 BTL2 5) DISINFECTION OR STERILISATION: The process of killing pathogenic bacteria and other micro- organisms is called ‘Disinfection or Sterilisation’. The chemicals used for killing bacteria are called ‘DISINFECTANTS’. Disinfection by Chlorination a) By adding Bleaching Powder: Water is mixed with required amount of bleaching powder, and the mixture is allowed to stand for several hours CaOCl2 + H2O à Ca(OH)2 + Cl2 Cl2 + H2O à HOCl (Hypo Chlorous Acid) + HCl Germs + HOCl à Germs are killed The disinfection action of bleaching powder is due to available chlorine in it. It forms hypochlorous acid which act as a powerful germicide (disinfectant) BREAK-POINT CHLORINATION  Involves in addition of sufficient amt. of chlorine to oxidise :organic matter, reducing substances. Dosage of applied chlorine to water rich in organic compound or ammonia is gradually increased.Four stages: The addition of chlorine at the dip or break : ’ breakpoint’ chlorination. This indicates the point at which free residual chlorine begins to appear. All tastes, odour disappear at break point : water free from bad tastes and odours UNIT: III ENGINEERIN GMATERIALS 69. Differentiate between CO4 BTL2 a) Addition polymerization from condensation polymerization. b) Monomer from polymer Addition polymerisation condensation Polymerisation Polymerisationpppolymerization.polyme Functionality rization. of the monomer is multiple Functionality of the monomer is bonds like double bond which is bifunction,tri,poly like reactive Polymerization bifunctional. takes place by self Its due to slow functional steplike groups wise –OH,- addition of monomers. condensation of the functional COOH,NH2,RCOOR’,HALIDES. No Rapidbymechanism. products formed Byproductsstep group.slow formed wiselike H2O,HCl.. mechanism. The monomers must be Molecular weight is sum of molecular dibasicacids,diols,diammines Not the sum or weights of monomers triolsetc The mechanism of polymerization Slow step wise condensation carried out in 3 steps ini,prop,termi Homopolymers are formed Heteropolymers are formed. - M-M-M-M- It is Highly exothermic process as the pi Not so much bonds are converted to sigma bond liberating An 20iskcal/mole initiator needed toofstart energy. A catalyst is needed Polymer has same composition like Polymer has different composition monomer. than monomer. Thermoplastics Thermosets like:Polyethylene,PVC,polystyrene likePolyesters,nylon,melamineetc  Monomers: The small individual molecules which combine with each other to form large molecules are called monomers. Examples: Ethylene, vinyl chloride, styrene, etc. POLYMERS (Poly = many; Mers = Part): Polymers are high molecular weight giant molecules formed by linking together of small molecules, monomers, by means of covalent bond/chemical bond. Examples: poly ethylene, poly (vinyl chloride), Bakelite, etc.. 70. Give the preparation, properties and Engineering applications of: CO4 BTL3 Nylon 6:6 Nylon 66: Preparation: It is prepared by the condensation polymerization of adipic acid with hexamethylene diamine. Properties: They are translucent, whitish, horny, high melting (160 - 2640C) polymers. They are resistance to high temperature and abrasion. They are insoluble in benzene, acetone and soluble in phenol, formic acid They have good strength and absorb little moisture. Uses of Nylons: Nylon 6:6 is used for making socks, dresses, carpets etc. It is also used in making gears, bearings, bushes etc. It is used for jacketing electrical ware and protects the electrical insulation. 71. Define and write one example for each: CO4 BTL2 a) Polymer b) Degree of polymerization. c) Co – Polymer (Poly = many; Mers = Part): Polymers are high molecular weight giant molecules formed by linking together of small molecules, monomers, by means of covalent bond/chemical bond. Examples: poly ethylene, poly (vinyl chloride), Bakelite, etc.. Degree of polymerization”. Number of monomers/repeat units present in the polymer is called “Degree of polymerization”. Example: 1. Co-polymerization: ✓ Co-polymerization is the joint polymerization of two or more monomers. ✓ This is mainly to vary the properties of polymers over a wide range.Examples: i. Buna-S (SBR) 72. Write the preparation and properties and applications of CO4 BTL3 BAKELITE Bakelite: It is the condensation polymer of phenol and formaldehyde. It is also known as phenoplast and PF resin.  Preparation: Bakelite preparation involves the following steps: Step (i): Phenol and formaldehyde react to form methylol derivatives which act as monomers for subsequent polymerization Step (ii): In presence of acid catalyst when mole ratio P/F>1. The methylol derivatives condense with phenol to form dihydroxy diphenyl methane. These on further condensation give low molecular weight linear polymers which are fusible , soluble and are known as “Novalacs” Step (iii): Further heating of Novalac in presence of hexamethylenetetramine [(CH2)6N4] as curing agent produces a hard, rigid , insoluble and infusible 3-D cross linked polymer known as “Bakelite”. Properties: Bakelite is hard, infusible and insoluble strong material. They have excellent heat, chemical resistance, but are affected by strong caustic alkalis. They have good electrical insulation characteristics. They have good abrasion resistance Uses: For making electrical insulating parts like switches, plug etc. For making telephone parts, cabinets for radio & television. In paints and varnishes. As ion exchange resin in softening of water by ion-exchange method 73. Distinguish between thermoplastics and thermosetting resins. CO4 BTL2 Thermoplastics Thermosetting polymers They soften on heating and harden on They are not softened on heating cooling reversibly. once set.Prolonged heating leads to charring. They are formed by addition or They are formed by condensation polymerization. condensation polymerization. They have either linear or These have 3D cross linked structures. branched structures. They can be recycled, re-moulded, re- They can’t be re-cycled, re- shaped and re-used. moulded, re-shaped. They are soluble in some organic They are insoluble in organic solvents. solvents They are tough & less brittle They are tough but more brittle. Ex: PE, PP, PVC, PMMA, Teflon. Ex: PF, UF, MF 74. Explain preparation properties and uses of PVC and Nylon 6:6. CO4 BTL2 Poly vinyl chloride (PVC) is obtained by heating a water emulsion of Vinyl chloride in presenceof benzoyl peroxide or H2O2 in an auto clave under pressure. Properties 1. Rigid PVC is a colourless, odourless and non-inflammable. 2. It has excellent oil resistance and resistance to weathering. 3. Due to the presence of ‘Cl’ atoms, hardness and stiffness of the polymer increases. 4. It has high chemical resistance , but soluble in ethyl chloride. Uses of Rigid PVC: It is used for making 1. Leather cloth used for car seat, covers etc 2. Kitchen upholstery, ladies hand bags, plastic rain coats 3. Baby pants, swim suits etc.  Nylon 66: Preparation: It is prepared by the condensation polymerization of adipic acid with hexamethylene diamine. Properties: They are translucent, whitish, horny, high melting (160 - 2640C) polymers. They are resistance to high temperature and abrasion. They are insoluble in benzene and acetone and soluble in phenol, formic acid etc. They have good strength and absorb little moisture. Uses of Nylons: Nylon 6:6 is used for making socks, dresses, carpets etc. It is also used in making gears, bearings, bushes etc. It is used for jacketing electrical ware and protects the electrical insulation 75. What is polymerization? Explain types of polymerisation with BTL- CO4 examples? 2 Polymerization: The process of joining together of small molecules by means of covalent bonds to form extremely large molecule is called polymerization. Types of polymerization: 1. Addition polymerization/Chain growth polymerization: ✓ Addition polymerization is a reaction that yields a polymer which is an exact multiple of monomers, without the elimination of by-products. ✓ Monomers having double bonds such as alkenes, alkynes, undergo addition polymerization. ✓ It is induced by heat or light or catalyst. Example : polyethylene 2. Condensation polymerization/step polymerization: ✓ Condensation polymerization is a reaction occurring between two bi – or poly functional monomers having polar functional groups. ✓ It always accompanies with elimination of small molecules like H2O, HCl, NH3, etc. ✓ For example, >C=O, -COOH, -OH and –NH2 carrying monomers undergo condensation polymerization. Example : Nylon 6,6. 3. Co-polymerization: ✓ Co-polymerization is the joint polymerization of two or more monomers. ✓ This is mainly to vary the properties of polymers over a wide range. Examples: i. Buna-S (SBR