CHM 2353 Lecture Notes - Lecture 9: Electronegativity, Molecular Mass, Alkene
7 Nov 2017
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Document Summary
Low molar mass and low polarity result in: low boiling and low melting point. Placed in group 1 on the periodic table, but is not seen as an alkali metal. Best balance between electron repulsion and nuclear attraction. Reaction of h2 with o2 fuels the main engines of space shuttles. 2 h2 (g) + o2 (g) + spark > 2 h2o (g) 2x more heat is released than with gasoline motors - more ef cient. Technological problems: requires very large volumes of h2, h2 (g) containers require heavy, thick walls, condensed h2 (l) requires very low temperatures to maintain liquid state - needs lots of energy, safety. Hydrogen and the hindenburg: he has been used as the lifting gas for hot air balloons ever since, but there"s a debate as to whether or not hydrogen is really responsible. H2 burns upwards, but the hindenburg ames burned downwards. H2 burns with colourless ames, but the hindenburg produced a reworks display .
