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MOD 1 Flashcards

1
Q

Causes of Hardness

A

Ca2+, Mg2+

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2
Q

Causes of Alkalinity

A

CO3-, HCO3-, OH-, Na+, K+

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3
Q

Causes of Acidity

A

CO2, SO2, H2S

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4
Q

What is Hardness?

A

Hardness is the property of water which does not form easy and permanent lather with soap.

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5
Q

What does hard water + soap form?

A

Insoluble white scum due to formation of insoluble soap of Ca2+ and Mg2+.

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6
Q

Chemical Formula of Soap?

A

C17H35COONa (sodium stearate/soap)

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7
Q

Chemical name of soap?

A

Sodium Stearate

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8
Q

Chemical formula of stearic acid

A

C17H35COOH

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9
Q

Temporary Hardness caused by?

A

bicarbonates HCO3-, carbonates (CO3)2-

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10
Q

Permanent Hardness caused by?

A

sulphates SO4 2-, chlorides Cl-

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11
Q

Degree french

A

no. of parts of calcium carbonate equivalent hardness per 10^5 parts of water

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12
Q

Clarke’s degree

A

No. of parts of calcium carbonate equivalent hardness per 70,000 parts of water

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13
Q

meq/l = mg/L = ppm?

A

1 meq/l = 50 mg/L = 50ppm

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14
Q

What is degree of hardness?

A

Degree of hardness is the number of milligrams of CaCO3 present in 1L of water

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15
Q

Why is CaCO3 chosen as standard?

A

mw = 100, ew = 50, Most insoluble salt, Easily precipitates

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16
Q

Degree of hardness = ?

A

(No. of hardness producing substance x 50)/ ew of hps

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17
Q

EDTA full form

A

Ethylene Diammine Tetra Acetic acid

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18
Q

EBT full form

A

Eriochrom Black-T

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19
Q

Why is buffer sol. used?

A

To maintain 9-10 pH

20
Q

What is the buffer sol. used in EDTA exp?

A

Ammonium chloride - ammonium hydroxide buffer ( NH4Cl-NH4OH)

21
Q

How is Hard water sol made?

A

1g CaCO3 + dil HCL dissolved in 1000ml of distilled water

22
Q

Ion exchange process is also known as?

A

demineralization process

23
Q

What is water softening?

A

Removal or reduction of hardness of water, irrespective of whether it is temporary or
permanent is termed as softening of water

24
Q

Principle of ion exchange?

A

Reversible chemical reaction.
Ion from solution is exchanged by a similarly charged ion.
The similarly charged ion is attached to an immobile solid particle.

25
EXAMPLES FOR SOLID ION-EXCHANGE PARTICLES?
Naturally occurring inorganic zeolites Synthetically produced organic resins
26
What is zeolites?
crystalline solids made of silicon, aluminium and oxygen
27
What is resin?
viscous substances convert into rigid polymers through a curing process
28
What are water softners?
Ion exchange units that replace calcium and magnesium ions from water are known as water softeners.
29
What do water softer units do?
Water softener unit work most efficiently with particulate free water. They will remove inorganic pollutants. They will not remove organic chemicals.
30
What kind of structure do resins have?
High molecular weight organic polymers with porous structure Insoluble & cross-linked. Functional groups attached to the chains are responsible for the ion exchange properties
31
CLASSIFICATION OF ION-EXCHANGE RESINS
Ion-exchange resins are classified into two types 1. Cation exchange resins (R-H+) 2. Anion exchange resins (R+OH-)
32
CATION-EXCHANGE RESINS (R-H+)
Cations from solution is exchanged with similarly charged ion (H+) attached to an immobile solid particle
33
example of cation exchange resin
Styrene-divinyl benzene co-polymer with functional groups like -SO3H, - COOH etc.
34
SYNTHESIS OF CATION-EXCHANGE RESINS
Sulphonation or carboxylation of styrene-divinyl benzene co-polymer. After sulphonation or carboxylation, they become capable of exchanging their H+ ions with the cations (Ca2+, Mg2+ etc.) in the water sample. These resins contain acidic functional groups like -SO3H, -COOH etc.
35
Why are cation exchangers called so?
They can exchange their cationic proton, so they are termed as cation exchangers.
36
COMMERCIAL CATION EXCHANGER
Amberlite IR-120 (Active group-SO3H).
37
ANION-EXCHANGE RESINS (R+OH-)
Anions from solution is exchanged with similarly charged ion (OH-) attached to an immobile solid particle.
38
Examples of anion exchange resins
Example: Styrene-divinyl benzene co-polymer with functional groups like amino, quarternary ammonium groups etc.
39
SYNTHESIS OF ANION-EXCHANGE RESINS
Treatment of styrene-divinyl benzene co-polymer with functional groups like amino, quarternary ammonium groups etc. with dilute NaOH. After treating with NaOH, they become capable of exchanging their OHions with the anions (Cl-, SO42- etc.) in the water sample. These resins contain basic functional groups
40
Why are anion exchangers called so?
They can exchange their anionic hydroxide ion, so they are termed as anion exchangers.
41
COMMERCIAL ANION EXCHANGER
Amberlite-400 (Active group - Quarternary ammonium hydroxide).
42
Advantages of ion exchange
Regeneration of resins. More efficient removal of dissolved salts. No sludge formation. Hardness of as low as 0-1 ppm Low maintenance cost (resin can be regenerated by using NaOH & HCl) Can be used in High pressure boilers Highly acidic and alkaline water can be treated.
43
Disadvantages of ion exchange
Capital cost is high. Turbidity will reduce the efficiency. Water having Fe2+ & Mn2+ cannot be treated - irreversible exchange reaction takes place.
44
ION-EXCHANGE PROCESS- STEPS
1. Two columns of cation exchange and anion exchange resins are prepared. 2. Hard water is first passed through the cation exchange column. 3. All the cations present in hard water (Ca2+, Mg2+ etc.) are exchanged with H+ ions from the column. 4. After this process the hard water is passed through anion exchange column. 5. All the anions present in hard water (Cl-, SO42- etc.) are exchanged with OH ions from the column.
45
The water coming out of the exchanger is called?
The water coming out of the exchanger will be free of cations & anions. Hence the water is called deionized or demineralized water.
46
When exchangers stop exchanging H+ and OHions then they are said to be?
Exhausted
47
hard water is first passed through cation exchanger and then through anion exchanger why?
For deionization, hard water is first passed through cation exchanger and then through anion exchanger. This is because cation resins are easily attacked by alkalis.

ENG CHEM (1 decks)

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