Hydrogen summary
- Created by: peter davenport
- Created on: 11-02-20 12:14
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- Hydrogen
- Industrial production
- Water - Gas shift reaction
- CO reacted with heated steam
- Yields CO2 and 1 mole H2
- CO reacted with heated steam
- Coal gassification
- Solid carbon heated to over 1000 degrees with steam
- Yields CO and 1 mole H2
- Solid carbon heated to over 1000 degrees with steam
- Catalysed electrolysis
- Ni anodes and Fe cathodes electrolyse water using overpotential
- Yields 1 mole of H2 per mole H2O
- Ni anodes and Fe cathodes electrolyse water using overpotential
- Steam reformation of natural gas
- Methane gas is reacted with steam over a catalyst
- Yields CO and 3 moles H2
- Methane gas is reacted with steam over a catalyst
- Chloro-alkali process
- NaOH generated from NaCl using water
- Generates 1/2 mole H2 per mole H2O as byproduct
- NaOH generated from NaCl using water
- Water - Gas shift reaction
- H+ & H- ions
- H+
- Extremely strong Lewis acid
- Tends to always be found with a Lewis base
- So strong it can interact with Helium
- But doesn't bond to the helium
- pH = -log[H+]
- Extremely strong Lewis acid
- H-
- Highly polarisable
- Mostly found in lattice arrangements
- E.g as a lattice with group 1 metals
- Other isotopes of H (D, T) also form these ions but are relatively useless
- H+
- Hydrogen Bonding
- Occurs when H bonded to atom with high electronegativity
- for E-H, E must have a lone pair for H bonding to happen
- E-H bond heavily polarised
- As such, LP on E can interact with H in other E-H molecule
- Singular H bonds very weak
- Collectivly, H bonds increase Bp e.g. H2O
- Compounds of Hydrogen
- Molecular hydrides
- Formed by P block elements and Be
- Acts as proton donors
- Acidity increases left to right and down periodic table
- Acts as proton donors
- All named with -ane suffix
- Normally compounds formed are electron precise
- Or electron rich. e.g. Ammonia, water
- Or electron deficient. e.g. borane
- As a result of the deficiency, compounds form 2 electron, 3 centre bonds as opposed to standard 2 centre, 2 electron bonds
- e.g. B2H6
- As a result of the deficiency, compounds form 2 electron, 3 centre bonds as opposed to standard 2 centre, 2 electron bonds
- Thermal decomposition to H2 and pure element
- Formed by P block elements and Be
- Saline hydrides
- Ionic solids with discrete H- ions
- Group 1
- Adopts Rock salt formation
- Group 2
- adopts Fluorite formation at high temp and lead chloride formation at low temp
- MgH2 adopts rutile formation
- Group 1
- All are insoluble in non-aqueous solutions
- Reacts violently with water
- Group 1 > Group 2
- Ionic solids with discrete H- ions
- Molecular hydrides
- Dihydrogen cleavage
- Either produce 2H radicals
- Homolytic cleavage
- Or produces H- & H+
- Heterolytic cleavage
- Requires very high energy and/or catalyst
- Usually done on a metallic surface or in solution
- natural catalysts such as metalloenzymes can cleave H2
- H2 can be broken by halogens in a free radical substitution mechanism
- X2 breaks to give 2X radicals. These then cleave H-H bond
- Either produce 2H radicals
- Industrial production
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