Hydrogen

Energy in a Covalent Bond

200 kJ/mol

Energy in a hydrogen bond

20-30 kJ/mol

Uses of Hydrogen Bonding

making water more dense than ice, hydrates, clathrates, cellulose, DNA and protein secondary structure, surface tension of water

clathrates

solid in which one component crystallizes in open structure into which a second small atom can be trapped

Hydrogen (H¹)

1.008 g/mol, 99.98% abundance

Deuterium (H²)

2.014 g/mol, 0.02% abundance

Tritium (H³)

3.016 g/mol, radioactive, B-emitter, half life of 12.4 years

process of deuterium formation

fractional distillation of water or electrolysis of water

preparation of hydrogen

1. obtained by reduction of H⁺

2. oxidation of a metal hydride

3. reformation of H2 from atomic hydrogen (releases heat)

4. preparation from fossil fuels

formation of atomic hydrogen

requires electric arcs, discharge tubes, UV radiation

Industrial preparation of hydrogen

steam reforming reaction (alkane and water at 800 degrees celcius to form CO and hydrogen gas)

water-gas shift reaction (CO and water react at 400 degrees C to form CO2 and Hydrogen gas)

CO2 is captured by scrubbers such as K2CO3

Haber-Bosch Process

ammonia production used for fertilizers and other important N compounds

nitrogen gas reacts with hydrogen gas at 400-600 degrees C and 150-600 atm to form ammonia

Haber-Bosch Process Catalyst

Fe

Formation of methanol

creates starting materials for plastics and synthetic fibers

reacts hydrogen gas and carbon monoxide at 300 degrees celsius and 250 atm

Catalyst for Formation of Methanol

Al2O3

hydrogenation addition of hydrogen gas to a C=C double bond

hydrogen gas reacts with an alkene and a Nickel Catalyst

Non-stoichiometric compounds

interstitial/metallic hydrides, can be thought of as H atoms occupying interstitial holes in metal lattice

Molecular compounds

consists of discrete compounds, H is covalently bonded to an element from the right side of the periodic table

saline hydrides

consists of the most electropositive metals (far left of periodic table) being ionically bound to hydride ions