CHEM 1300 Lecture Notes - Lecture 18: Sucrose, Stained Glass, Rock Candy
26 Jun 2018
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Lecture 18
●Mixing 2 immiscible liquids
oPhysical mixing – temporary
oEmulsifying – permanent
▪Using an emulsifying agent
▪Has a polar and non-polar region to bind the immiscible layers together
▪E.g. soap
▪Metal ions in hard water bind to polar end of soap creating soap scum from
soap not washed away
●Melting point/boiling point of polar substances
oThe more polar a liquid or substance is, the higher the melting or boiling point
oA non-polar substance will have a very low melting/boiling point and generally be a gas
in its natural state at normal pressure/temperature etc.
Ethanol Dimethylether Propane
Structure
Molecular Weight (g) 46 46 44
Dipole Moment 1.69 (most polar) 1.30 (polar) 0.083 (non-polar)
Crystalline Solid Types (Increasing in Bond Strength & mp/bp)
●Molecular Solids Intermolecular forces
●Metallic Solids Bond Order, Band Theory
●Network Solids Covalent Bonding
●Ionic Solids E=kq1q2/r, Lattice Energy
Molecular Solids
●Organic Compounds
●Held together by intermolecular forces:
o(London) dispersion
oDipole-dipole, hydrogen bonding, π-π stacking (aromatics)
oAt lattice sites
oLowest mp/bp
Metallic Atomic Solids
●e- sea model
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Crystalline solid types (increasing in bond strength & mp/bp) Held together by intermolecular forces: (london) dispersion, dipole-dipole, hydrogen bonding, - stacking (aromatics, at lattice sites, lowest mp/bp. Model allows for deformation and relocation of atoms without changing electronic structure: how we can cut off a piece of metal and have 2 pieces of the same material. Structure shape is dependent on vsepr shapes/angles. To surpass this bond, you must break the bonds between the atoms, not the forces holding them together. Very difficult to break these bonds: very high mp/bp. May have allotropes: different forms of a single kind of chemical structure, different bonding and hybridization only, e. g. Amorphus: disorder in solids: no regular repeat of atoms/bonding structure, formed by a quick cooling or freezing, result is a locked in structure with randomized shape, also formed by an extremely viscous liquid, glass: Born haber cycle: note: unit cells (the crystalline network) is neutral.
