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CHEMISTRY > WATER > Flashcards

WATER Flashcards

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1
Q

Type of water in textile industry

A

Water should be soft and free of organic matter. I hard water is used uniform dying is not possible as it decreases the solubility of acidic dyes.
If water contains Fe,Mn it causes uneven dyeing

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2
Q

Type of water in Laundries

A

they require soft water as hardness increases soap consumption of soaps. Salts of Fe and Mn impart a grey or yellow shade to the fabric

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3
Q

Type of water used in Boilers

A

they require water of 0 hardness otherwise efficient heat transfer is prevented. It can also lead to the corrosion of boiler material and even explosions

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4
Q

Type of water required in paper industry

A

it requires water free from
SiO2 (produces cracks in paper)
turbidity (they affect brightness and colour of paper)
alkalinity (consumes alum and increases cost of production)
hardness (they increase ash content of paper)

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5
Q

type of water used in beverages

A

should not be alkaline as it destroys or modifies the taste as it tends to neutralize fruit acids

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6
Q

type of water used in sugar industry

A

use of hard water leads to deliquescent sugar

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7
Q

type of water used in cooking

A

water should be free from dissolved salts producing hardness as it increases fuel consumption

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8
Q

water treatment

A

process by which all types of undesirable impurities are removed from water and making it fit for domestic or industrial purposes

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9
Q

Sources of water

A

surface water
underground water
rain water
sea water

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10
Q

Hardness of water

A

characteristic of water which prevents the lathering of soap
or
soap consumption capacity of water

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11
Q

hard water + soap

A

when treated with soap it does not produce lather but on the other hand forms insoluble white scum or precipitate which do not produce any detergent action

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12
Q

Hard water vs Soft water

A

Hard water:
1) does not produce lather with soap solution
2) contains Mg and Ca salts in it
3)cleansing quality of soap is depressed
4) boiling point is elevated

Soft Water:
1) easily forms lather
2)does not contain Mg and Ca salts in it
3)cleansing quality of soap is not depressed

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13
Q

alkalinity

A

alkalinity is a measure of ability of water to neutralise the acids

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14
Q

Types of alkalinity

A

Caustic alkalinity (due to OH- and CO3 2- ions)
temporary hardness (due to HCO3 -)

OH- only
CO3 2- only
HCO3 - only
OH- and CO3 2- together
CO3 2- and HCO3 - together

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15
Q

why alkalinity cannot be due to simultaneous presence of OH- CO3 2- and HCO3 - together

A

OH- and HCO3 - combine together to form CO3 2- ions. thus they cannot exist together

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16
Q

Titration curves for various cases of alkalinity

A

Book pg 7

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17
Q

why both P and M indicators are required to determine the type and amount of alkalinity in given water sample

A

book pg 11

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18
Q

Types and extent of alkalinity due to various anions

A

book pg12

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19
Q

drawbacks of highly alkaline water

A

caustic embrittlement
deposition of precipitate and sludges in boiler

20
Q

Temporary hardness

A

presence of dissolved bicarbonates of Ca, Mg and other heavy metals and carbonates of iron

can be removed via boiling

21
Q

Temporary hardness is aka

A

carbonate hardness and alkaline hardness

22
Q

water for drinking should not be soft

A

soft water is plumbo-solvent and it attacks lead used in plumbing. solubility of lead in water is diminished in the presence of HCO3 - ions

23
Q

Permanent hardness

A

it is due to dissolved chlorides and sulphates of calcium magnesium iron and other heavy metals

24
Q

removal of permanent hardness

A

lime-soda process
zeolite process
ion-exchange process

book pg 19

25
Q

Permanent hardness is aka

A

non-carbonate hardness or non-alkaline hardness

26
Q

carbonate hardness

A

hardness due to the presence of carbonates and bicarbonates is referred to as carbonate hardness

27
Q

advantages of hard water

A

taste is better
calcium in water helps with teeth and bones

28
Q

disadvantages of hard water

A

produces scum with soap. this dulls the clothes
boiler water should be free of hard water

29
Q

why is hardness expressed in terms of CaCO3

A

Although hardness is never present in form of CaCO3 since it is insoluble in water, hardness is expressed in terms of CaCO3 as it has a molecular weight of 100 which eases the calculation

30
Q

ppm

A

number of parts by weight of CaCO3 present per million parts by weight of water

31
Q

mg/L

A

number of mg of CaCO3 present in 1 litre of water

32
Q

degree clarke

A

parts of CaCO3 equivalent hardness per 70000 parts of water

33
Q

degree french

A

parts of CaCO3 equivalent hardness per 100000 parts of water

34
Q

relation btw units of hardness

A

1ppm = 0.1Fr = 0.07Cl = 1mg/L

35
Q

Boiler

A

a boiler is a closed vessel in which water under pressure is transformed into steam by the application of heat

36
Q

Uses of steam generated by boiler

A

trubine drive for electric generating equipments
heating and air conditioning
sterilization

37
Q

composition of boiler feed water

A

hardness below 0.2ppm
caustic alkalinity btw 0.15-0.45 ppm
soda alkalinity btw 0.45-1ppm

38
Q

Hardness of boiler feed water causes

A

scale formation which leads to wastage in fuel, lowering of boiler safety, decrease in efficiency and danger of explosion

39
Q

caustic alkali in boiler feed water causes

A

caustic embrittlement

40
Q

dissolved gases in boiler feed water causes

A

boiler corrosion

41
Q

turbidity and oils in boiler feed water causes

A

tendency for priming and foaming

42
Q

Sludge

A

soft loose and slimy precipitate formed within the boiler

43
Q

sludge formation

A

substances which have greater solubilities in hot water than cold water (eg. MgCO3, MgCl2, CaCl2, MgSO4). They are formed at a comparatively colder portions of boiler and get collected at places where the flow rate is slow. They can easily be scrapped by wire brush

44
Q

what happens when sludges are formed alongside scales

A

former gets entrapped in the latter and both get deposited as scales

45
Q

Disadvantages of sludge formation

A

1) poor conductors of heat so they tend to waste a portion of heat generated and thus decrease the efficiency of boiler

2) excessive sludge formation disturbs the working of boiler . it settles in the region of poor water circulation thereby causing choking of pipes

46
Q
A

CHEMISTRY (3 decks)

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