T1 HYDROGEN Flashcards
The existence of life depends o twoparticular properties of hydrogen that are..
- The closeness of the electronegativity of carbon and hydrogen
- The ability of hydrogen to form hydrogen bonds when covalently bonded to N or O.
How do alkali metals react with water? and hydrogen is the same?
Violently (and hydrogen does not)
Does hydrogen have oxidizing power?
NO
What are the reasons why hydrogen should be place with the Alkali metals?
- 1s1
- Metallic at high P
- Forms H+
What are the reasons why hydrogen should be place with the halogens?
- Non-metal
- Diatomic molecule
- C - H bonds
Where should hydrogen be place in the periodic table?
In the middlemof the periodic table.
What is the abundance of hydrogen in the Universe? And in earth?
Most abundance in the universe, 3rd most abundance on earth.
What are the 3 more important Isotopes of hydrogen?
- PROTIUM
- DEUTERIUM (D)
- TRITIUM (T)
How many neutrons does hydrogen have?
0
How many neutrons does deuterium have?
1
How many neutrons does tritium have?
2
What is more abundant H2, D2 or T2?
ABUNDANCE:
H2»_space;> D2»_space; T2
With have the higher melting and boiling point H2, D2 or T2?
T2
D and T form stronger bonds with other elements or with H?
With other elements
D and T are used as markers to follow the reaction mechanism where there is a….., determining the isotopic composition by….
transfer of H or H2O/ NMR, IR or mass spectrometry.
H2 can be obtain by different methods such as….
- Reduction of H2O
- Electrolysis of H2O
- Steam reforming of natural gas
- Coal gasification
- Thermochemical water splitting
- Direct photoelectrochemical water splitting
- Biological processes
- Cloroalkali process
- Cracking process
The reduction of H2O metho consist in preparing H2 by…
reduction of H20 with a reducing agent, normally Zn.
The electrolysis method is done using…
H2SO4 as an electrolyte.
The method of coal gasification is perform by…
passing steam and oxygen over coal in the presence of a catalyst.
The method of thermochemical water splitting uses….., to drive a series of….
high temperatures from solar or nuclear power plants / chemical reactions to produce hydrogen.
The method of direct photoelectrochemical water splitting uses…
semiconductors materials to produce potential that electrolyzed water.
The biological processes to produce H2 is done by…
some microorganism that digest and realease hydrogen in the dark fermentation process.
The cloroalkaliprocess produce…
chlorine and sodium hydroxide from electrolysis of NaCL solution.
The cracking process is important in the production of…
petrol.
In the cracking process a common reaction is the…
alkane deshydrigenation.
Physical properties of H2
- Colorless gas
- Odorless gas
- Lowest density of all
H2 is relatevely inert due to…
high H-H bonding
What bonds are the only ones that are higher than the H-H bond?
H-O
H-F
(Thats why H2 reacts violently with F2 and O2)
At high T, H2 can reduce some…
metals oxides to the elemtent.
With a catalyst H2 reduces….
doble and triple bonds to simple bonds.
Is H2 reactive at ambient conditions?
Nor very
What is the origin of the lack of reactivity of H2?
Kinetic origin caused by the strengh of the H-H bond.
The interaction between the surface of a catalyst and H2 …. and allows it to break.
weakens the H-H bond
H2 can undergo reactions through 2 possible activation mechanisms:
- HOMOLYTIC CLEAVAGE
- HETEROLYTIC CLEAVAGE
The homolytic cleavage occurs at the surface of …
Pd and Pt.
The homolytic cleavage is important in the…
catalytic hydrogenation of alkenes and other organic compounds.
What is produced in the homolytic cleavage with halogens?
A radical chain
The heterolytic cleavage occurs on the surface of…
Cu and Zn
The heterolytic cleavage is important in the…
catalytic conversion of CO methanol.
What is the reaction of the homolytic cleavage?
H2 –> 2 H+
What is the reaction of the heterolytic cleavage?
H2 –> H+ + H-
Applications of hydrogen:
- Synthesis of NH3
- Hydrogenation of unsaturated fats and oils
- Reduction of metallic oxides
- Production of MeOH
- Hydrodealkylation reactions
- Hydrodesulfurization
- Hydrocracking
- Production of HCL
- Welding
- Coolant
- Liquid propellant
- Ballons and airships
What is the main use of H2?
Synthesis of NH3
How is name the process of synthesis de NH3 using H2?
Haber-Bosch process in the presence of a Fe catalyst.
The Haber-Bosch reaction has a …
high activation energy
NH3 is the starting material in the…
fertilizer industry and the fabrication of explosives.