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water Flashcards

1
Q

water constitution in human body

A

65%

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2
Q

water constitution in plants

A

95%

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3
Q

existence of h bonding in water is responsible for

A

high freezing point
high boiling point
high latent heat of fusion
high latent heat of vaporisation

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4
Q

latent heat of vaporisation order
H2O H2S H2Se H2Te

A

H2S < H2Se < H2Te < H2O
due h bonding

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5
Q

H2O bond angle in gas phase

A

104.5 degree

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6
Q

O-H bond length in gas phase H2O

A

95.7 pm

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7
Q

ice structure

A

open cage like structure
extensive h bonding
each O atom attached to 4H, two by covalent bond, two by H bond

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8
Q

density compare
ice/water

A

water > ice

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9
Q

density of water is max at

A

4’C

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10
Q

two effects balancing each other that make density of water max at 4’C

A

thermal expansion and
breaking of hydrogen bonds

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11
Q

water nature
(acidic/basic/amphoteric)

A

amphoteric

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12
Q

auto-protolysis
self-ionisation
of water

A

H2O(l) + H2O(l) <–> H3O+ + OH-

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13
Q

water act as
(oxidising/reducing agent)

A

both

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14
Q

water dielectric constant

A

78.4
water is an excellent solvent

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15
Q

P4O10 + 6H2O –>

A

4H3PO4

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16
Q

SiCl4 + 2H2O –>

A

SiO2 + 4HCl

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17
Q

SO3 + H2O –>

A

H2SO4

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18
Q

CaC2 + 2H2O –>

A

Ca(OH)2 + C2H2

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19
Q

CaH2 + 2H2O –>

A

Ca(OH)2 + 2H2

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20
Q

AlN + 3H2O –>

A

Al(OH)3 + NH3

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21
Q

Ca3P2 + 6H2O –>

A

3Ca(OH)2 + 2PH3

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22
Q

types of hydrates

A
  1. water molecules coordinated to metal ion
  2. water molecule occupies interstitial sites in crystal lattice
  3. water molecules are h bonded to certain oxygen containing anion
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23
Q

water molecules coordinated to metal ion
example

A

[Cr(H2O)6]Cl3
[Fe(H2O)6]Cl3

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24
Q

water molecule occupies interstitial sites in crystal lattice
example

A

BaCl2.2H2O

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25
water molecules are h bonded to certain oxygen containing anion example
CuSO4.5H2O [Cu(H2O)4]2+ SO4 2- . H2O
26
hard water?
does not produce lather with soap easily
27
hard water contains
Ca and Mg salts in form of bicarbonates, chlorides and sulphates
28
soft water?
produce lather with soap easily
29
sodium stearate (soap)
C 17 H 35 C O O Na
30
M2+ + 2C17H35COONa --> M = Ca / Mg
(C17H35COO)2M (ppt) + 2Na+
31
temporary hardness is due to presence of
bicarbonates of Ca and Mg
32
permanent hardness is due to presence of
chlorides and sulphates of Ca and Mg
33
removal of temporary hardness
1. boiling 2. clark method
34
boiling removes temporary harness by
during boiling 1. soluble Mg(HCO3)2 --> Mg (OH)2 (ppt) + 2CO2 2. Ca(HCO3)2 --> CaCO3 (ppt) + H2O + CO2 3. this ppt is flitered out 4. filtrate obt is soft water
35
Mg(HCO3)2 --> during boiling
Mg (OH)2 (ppt) + 2CO2
36
Ca(HCO3)2 --> during boiling
CaCO3 (ppt) + H2O + CO2
37
Clark's method removes temp harness by
1. adding lime to hard water 2. Ca(HCO3)2 + Ca(OH)2 --> 2CaCO3 (ppt) + H2O Mg(HCO3)2 + 2Ca(OH)2 --> 2CaCO3 (ppt) + Mg(OH)2 (ppt) + 2H2O 3. ppt is flitered 4. filterate is soft water
38
Ca(HCO3)2 + Ca(OH)2 --> in clarks method
2CaCO3 (ppt) + H2O
39
Mg(HCO3)2 + 2Ca(OH)2 --> in clarks method
2CaCO3 (ppt) + Mg(OH)2 (ppt) + 2H2O
40
removal of permanent hardness process
1. treatment with washing soda 2. calgon method 3. ion exchange method 4. synthetic resin method
41
how washing soda removes permanent hardness of water
by forming ppt of CaCO3 and MgCO3
42
CaCl2 + Na2CO3 -->
CaCO3 (ppt) + 2NaCl
43
MgSO4 + Na2CO3 -->
MgCO3 (ppt) + Na2SO4
44
calgon is commercial name of
hexametaphosphate Na6P6O18
45
Na6P6O18
calgon hexametaphosphate
46
Na6P6O18 --> calgon method
2Na+ + Na4P6O18 2-
47
M2+ + Na4P6O18 2- --> calgon method
[Na2MP6O18]2- + 2Na+ M = Mg, Ca
48
principle of ion exchange method
exchanging ions responsible for hardness of water to less damaging ions
49
ion exchange method employs the use of
zeolite or permutit hydrated sodium aluminium silicate NaAlSiO4
50
ion exhange process is also known as
demineralisation permutit or zeolite process
51
2NaZ + M2+ -->
MZ2 + 2Na+ M = Mg, Ca
52
regeneration of permutit rxn
MZ2 + 2NaCl --> 2NaZ + MCl2
53
synthetic resin method is more superior to ion exhange process. why
because they remove all types of unwanted cations as well as anions in the water
54
synthetic resins physical properties
1. insoluble polymeric solid 2. giant hydrocarbon network 3. contain reactive acidic or basic group
55
synthetic resin types
1. cation exchange resins 2. anion exchange resins
56
diff between cation and anion exchange resin
cation has acidic group (-SO3H) anion has basic group (-NH2 / OH-)
57
how cation exchange resin works
1. contain large acidic group like -SO3H 2. hard water is passed through bed of cation exchanger 3. RSO3H + NaCl --> RSO3Na 4. RNa resin exchange Na+ ions with Ca+ and Mg2+
58
2Resin-SO3Na + M2+ -->
(Resin-SO3)2Ca + 2Na+
59
2R-COOH + Ca2+ -->
(RCOO)2Ca + 2H+
60
anion exchange resins contain
1. giant HC framework 2. basic groups like NH2 and OH-
61
RNH2 + H2O -->
RNH3OH
62
RNH3OH + X- -->
RNH3X + OH-
63
resins are regenerated by
1. cation exhanger by dil acid 2. anion exchanger by dil alkali
64
degree of hardness unit
ppm parts per million
65
which dissociates more protium water (H2O) or heavy water (D2O)
H2O > D2O dissociation extent

Hydrogen (4 decks)

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