chem Flashcards
define fuels & state characteristics of a good fuel.
Any substance used to produce heat or power by combustion.
*low cost
*low moisture content
*high calorific value
*easy to store and transport
Define hardness of water. differentiate b/w temporary and permanent hardness.
property of water to form an insoluble curd with soap instead of lather.
Temporary:
*due to bi-carbonates
*alkaline hardness
*softned by boiling
*carbonate hardness
Permanent:
*due to nitrates, sulphates & chlorides
*non-alkaline hardness
*softned by lime soda process
*non carbonate hardness
Describe ion-exchange process of water softening with diag. & chemical reactions. Write any 2 advantages.
AKA deionization it removes all inorganic salts.
In ion-exchange process the hydrogen cations replace the metal ions in dissolved salts & convert them into acids. Basic anion exchange removes these acids and helps in controlling of ph, lowering conductivity and removing of ionic substances.
Resins are certain organic compounds that are capable of exchanging of ions. i. Cation exchange resins: exchange +vely charged ions ii. Anion exchange resins: exchange -vely charged ions.
cation exchange column:H2R
H=hydrogen ion
R=organic part
anion exchange column:R(OH)2
R=organic part
OH=hydrogen ion.
CATION
CaCo3+H2R=CaR+H2Co3
CaCl+H2R=CaR+2Hcl
ANION:
ROH+Hcl=Rcl+HOH(H2O)
2ROH+H2SO4=R2SO4+HOH(H2O)
Advantages:
*Helps in removal of ionic substances
*Controls PH
*Reduction of conductivity
State composition, properties & application of CNG
COMPOSITION: methane: 88.5% ethane: 5.5% butane: 1.8% pentane: 0.5% propane: 3.7%
PROPERTIES: *cheap
*calorific value is around 8000-14000 kcal/m^3
*high ignition temp, so safer than other fuels.
*undergoes complete combustion
APPLICATION: *used as fuel in automobiles
*source of carbon black and hydrogen gas
*used in production of glass
Define electrical conductance and the factore affecting it.
DEFINATION: ability of electrolytic solutions to allow passage for electric current through them.
FACTORS
*temperature
*size of ion
*concentration of ions
*viscosity of solvent
*Nature of electrolyte
*Nature of solvent
Define battery?explain charging and discharging process in lead acid storage cell
A combination of 2 or more cells in series or parallel connection.
Lead acid storage cell is a secondary battery. They can be charged again and again by passing electricity through them. Discharging happens when they are at use.
Composition, properties and application LPG
Extracted from wet natural gas. Mixture of hydrocarbons: Propane, Propylen, Butane, Butylene, Isobutane.
PROPERTIES: *Colorless & odorless *1/2 as heavy as the weight of water when in liquid form *It can be converted into liquid by pressure
APPLICATION : *high end industries
*cooking gas
*refrigerator
*used as motor fuel
Describe zeolite process of water softening and advantages
It is hydrated sodium alumino silicate which exchanges its sodium ions for hardness producing ions for softening of water.
Hard water is percolated at a specific rate through a bed of zeolite kept in a cylinder.The hardness causing ions Ca, Mg are retained by zeolite in form of Caze and Maze and the remaining outgoing water contains salt.
ADVANTAGES
*Requires less space
*Obtained water is pure
*less than 15ppm water can be obtained
Define proximate analysis? Explain proximate analysis for for determining moisture and volatile matter in coal sample
Proximate analysis is an easy and quicker way to determine approx quality of coal. It determines ash, moisture content, volatile matter and carbon matter.
Volatile matter: take a known weight W of coal sample in cruicble, put the lid on and heat it for 7 min at 950-970 degree
Volatile matter=loss of weight/weight of coal sample * 100
Moisture content: take 1 gram of powered coal and heat it at 105-110 degree for 1 hour in electric oven
Moisture content=loss of weight/weight of coal sample *100
Whats the bad effect of using hard water in boiler unit
Scales: Deposits firmly sticking to the inner surface of the boiler that can’t be removed mechanically.
Sludges: loose, slimy and soft ppt formed on the inner walls of the boiler that can’t be removed mechanically.
Caustic embrittlement: makes the boiler material brittle due to high use of alkaline water.
Boiler corrosion: It is caused due to Co2, O2, dissolved gases.
Explain the types of battery
Primary battery: produces electrical energy in spontaneous redox reaction, non-rechargable, used at home and portrable devices eg dry cell
Secondary battery: rechargable, can be recharged again and again by passing electricity through it eg. lithium ion battery
reverse cell: reactions are reversible used in large vehicles.
Write a note on dry cell
Dry cell is non rechargeable cell it is called dry cell as it doesn’t contain any liquid it consists of a cylindrical container made up of zinc which acts as anode carbon rod is placed in the centre of the zinc container acting as a cathode then a paste of Ammonium Chloride and zinc chloride is made and filled between the carbon rod and the zinc container the remaining portion of the cell is added with the paste of mno2 and carbon does the cell is covered with sawdust at the top now this cell produces an eMF of 1.5V
Explain lithium-ion battery
Lithium ion batteries are secondary batteries which are the chargeable it consists of three sheets pressed together the positive electrode, negative electrode and a seperator. the anode is a layered solid of lithium colbat oxide and the cathode is a layers solid of Graphite. separator is a thin sheet of microporous plastic that separates the anode and cathode while allowing ions to pass through it
Advantages and disadvantages of lithium ion battery
Advantages
-high energy density
-rechargeable
-no need to completely discharge before charging
Disadvantages
-Sensitive to high temperature
- relatively expensive
-if separator is damage it can burst into flames
-expires in 2-3 years of manufacture
Working and construction of fuel cell
A fuel cell converts chemical energy into electrical energy. It can produce electricity as long as hydrogen and Oxygen gas are supplied. It has three compartments: the middle one contains a concentrated solution of KOH, while the anodic compartment receives dry H2 and the cathodic compartment receives pure dry O2.
