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Hydrogen > hydrogen > Flashcards

hydrogen Flashcards

1
Q

hydrogen occurs in its atomic form at

A

high temperature

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2
Q

name hydrogen is given by

A

lavoiser
as hydro means water and gene means forming in greek

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3
Q

hydrogen exhibits similar properties as of

A

alkali metals (group 1)
halogens (group 17)

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4
Q

difference between alkali metals and h2

A

ionisation energy is very high
size is much small

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5
Q

difference between halogen and hydrogen

A

less reactive
electron affinity is much low as of halogens

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6
Q

predominant isotope of hydrogen

A

protium
1H1

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7
Q

heavy hydrogen

A

deuterium
2H1 or D

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8
Q

deuterium is found in terrestrial region in the form of

A

HD
0.0156% deuterium is mostly in ofrm of HD

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9
Q

radioactive isoptope

A

tritium
3H1 or T

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10
Q

tritium emits

A

low energy B- particles having half life period of 12.33 years

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11
Q

most abundant element in the universe

A

dihydrogen
H2

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12
Q

laboratory preparation of H2

A
  1. granulated zinc with dil HCl acid or dil H2SO4
    Zn + 2H+(dil) –> Zn2+ + H2
  2. zinc with aqu alkali
    Zn + 2NaOH –> Na2ZNO2 + H2
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13
Q

granulated zinc with dil HCl acid or dil H2SO4

A

Zn + 2H+(dil) –> Zn2+ + H2

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14
Q

zinc with aqu alkali

A

Zn + 2NaOH –> Na2ZNO2 + H2

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15
Q

pure zinc is not used in laboratory prep as

A

it reacts slowly with H2SO4 and addition of some impurities enhances rate of rxn

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16
Q

commercial production of H2

A
  1. electrolysis of water
    2H2O –> 2H2 + O2
  2. electrolysis of aqu Ba(OH)2
  3. electrolysis of brine
    2Cl- + 2H2O –> Cl2 + H2 + 2OH-
  4. action of steam on coke
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17
Q

catalyst used in action of steam on coke

A

nickel
1270K

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18
Q

action of steam on coke reactions

A

C + H2O –> CO + H2
nickel catalyst (1270K)

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19
Q

water gas

A

CO + H2
synthesis (syn) gas

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20
Q

CO + H2

A

water gas or synthesis gas

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21
Q

when syn gas is produced from coke, it is known as

A

coal gasification

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22
Q

water gas shift reaction

A

CO + H2O –> CO2 + H2
673 K
catalyst = FeCrO4

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23
Q

catalyst used in water gas shift rxn

A

FeCrO4

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24
Q

CO2 is removed in water gas shift rxn by

A

scrubbing with sodium arsenite solution
(NaAsO₂)

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25
Q

nascent hydrogen

A

newly born hydrogen
Zn + H2SO4 –> ZnSO4 + 2H

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26
Q

adsorbed hydrogen is also known as

A

occluded hydrogen

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27
Q

occluded hydrogen is also known as

A

adsorbed hydrogen

28
Q

adsorbed hydrogen

A
  1. more active
  2. stronger reducing agent than ordinary
  3. hydrogen occupies hole in crystal lattice of metal like Pt/Au/Fe/Ni/etc.
29
Q

atomic hydrogen is formed by

A

when H2 is heated at low pressure, it gets dissaciated in atomic H2

30
Q

nuclear spin isomers

A

ortho and para hydrogen
(spin isomers)

31
Q

ortho hydrogen spin

A

same direction (nuclei spin)
electrons opposite spin (pauli)
+1/2 +1/2 = +1
triplet state

32
Q

para hydrogen spin

A

opposite direction (nuclei spin)
electrons opposite spin (pauli)
+1/2 -1/2 = 0
singlet state

33
Q

compare internal energy
ortho/para hydrogen

A

para < ortho
as resultant spin of
ortho = 1
para = 0

34
Q

relative proportion of ortho - para hydrogen at absolute zero temperature

A

pure para
para:ortho = 1:0

35
Q

relative proportion of ortho - para hydrogen at temperature of liquefction of air

A

equal ratio
para:ortho = 1:1

36
Q

relative proportion of ortho - para hydrogen at room temperature or elevated temperature

A

ortho major
para:ortho = 1:3

37
Q

compare thermal conductivity
ortho-para hydrogen

A

para has 50% more than that of ortho
para > ortho

38
Q

compare melting point
ortho-para hydrogen

A

ortho > para

39
Q

ortho para conversion is slow without catalysts. some catalysts are

A

atomic H2
activated charcoal
metals like Fe, Ni, Pt, W
paramagnetic species like O2, NO, NO2, Co2+, Cr2O3

40
Q

pure para hydrogen can be achieved at

A

-20 K

41
Q

conversion of para to ortho hydrogen

A
  1. heating at 800C or above
  2. passing electric discharge through para-H
  3. treatment with catalysts
  4. mixing para-H with paramagnetic molecule like O2
  5. mixing para-H with atomic hydrogen
42
Q

mixing para-H with atomic hydrogen gives

A

ortho-H

43
Q

reaction of H2 with halogens

A

H2 + X2 –> 2HX
F, occurs even in dark
H2 + F2 –> 2HF
Cl, occur in presence of sunlight
H2 + Cl2 –> 2HCl
Br, only on heating
H2 + Br2 –> 2HBr
I, requires catalyst Pt
H2 + I2 –> 2HI

44
Q

H2 + I2 –> 2HI
catalyst

A

Pt
673 K

45
Q

reactivity of halogens with dihydrogen

A

F2 > Cl2 > Br2 > I2

46
Q

H2 with dioxygen rxn

A

2H2 + O2 –> 2H2O
exothermic

47
Q

H2 with dinitrogen rxn

A

3H2 + N2 –> 2NH3
Fe catalyst
673K, 200atm
haber’s process
formation of ammonia

48
Q

catalyst used in habers process

A

3H2 + N2 –> 2NH3
Fe catalyst
673K, 200atm

49
Q

H2 with metals rxn

A

yield hydrogen
H2 + 2M –> 2MH
M = alkali metal

50
Q

2Na + H2 –>

A

2NaH

51
Q

Ca + H2 –>

A

CaH2

52
Q

H2 with metal ions and metal oxides

A

reduces metal ions and oxides (less active than Fe) into corresponding metal
H2 + MxOy –> M + H2O

53
Q

H2 + CuO –>

A

Cu + H2O
endothermic

54
Q

H2 + Pbo –>

A

Pb + H2O

55
Q

H2 with unsaturated hydrocarbons

A

H2(g) + unsatu HC –> satu HC
catalytic hydrogenation
Ni catalyst
473K

56
Q

C=C + H2 –>

A

CH3-CH3
Ni catalyst
473K

57
Q

hydrogenation of vegetable oil

A

vegetable oil + H2 –> Fat(s)
Ni catalyst
473 K

58
Q

hydroformylation of olefins

A

olefin + CO + H2 –> aldehyde
RC=C + CO + H2 –> RCH2CH2CHO

aldehyde further reduce to alcohol
RCH2CH2CHO + H2 –> RCH2CH2CH2OH
Pt catalyst

59
Q

CO + 2H2 –>
catalyst also

A

CH3OH (L)
Co catalyst

60
Q

used as

A
  1. metallurgical process
  2. cutting and welding
  3. rocket fuel
  4. fuel cells
61
Q

compare bond dissociation energy
H2 D2 T2

A

H2 < D2 < T2

62
Q

compare bond strength
C-H ; C-D ; C-T

A

CH < CD < CT

63
Q

compare dielectric constant
H2O D2O

A

H2O > D2O

64
Q

___ is obtained as a by product in fertiliser industry

A

D2O

65
Q

______ is used as a moderator in nuclear reactor

A

D2O

66
Q

____ is used for study of rxn mechanism

A

D2O

67
Q

H2 with high purity is obtained through

A

electrolysis of warm Ba(OH)2 solution using Ni electrodes

Hydrogen (4 decks)

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