MCAT chem*1 – Flashcards
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| # electron domains around atom=2 hybridization angle geometry |
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| sp 180 linear |
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| # electron domains around atom=3 hybridization angle geometry |
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| sp2 120 trigonal planar |
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| # electron domains around atom=4 hybridization angle geometry |
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| sp3 109.5 tetrahedral |
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| more electron density effect on angles (such as a pi bond) |
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| more repulsion= a little bit bigger angle |
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| strong acid pKa/Ka |
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| low pKA, high Ka |
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| the stronger the acid, the __ conjugate base |
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| weaker |
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| a stable base is |
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| a weak base |
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| ranking bases |
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| CARDO charge, atom, resonance, dipole induction, orbitals |
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| CARDO Charge |
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| more negative charges species are more basic |
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| CARDO Atom |
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| the larger (vertical) and more electronegative (horiz) the more stable it is =weaker |
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| CARDO resonance |
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| resonance= e- stability = stability= weaker |
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| CARDO dipole induction |
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| EWG near the negatively charged atom stabilizes it= makes weaker |
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| CARDO orbitals |
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| more stable: sp > sp2 > sp3 |
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| whats the strongest base? :CH3- :OH- NH2- |
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| CH3 > NH2 > OH |
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| intermolecular forces |
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| hydrogen bonding dipole-dipole london despertion/van der waals |
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| hydrogen bond |
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| F-H O-H N-H |
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| dipole dipole forces |
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| interactions btw molecules w/permanent dipole moments H-Cl---H-Cl |
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| london despertion/ van der waals |
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| all molecules have these, even non polar weakest spnt dipole goes away |
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| Rank boiling points w/ intermolecule forces |
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| network covalent (diamond) ionic H bond dipole london |
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| high BP means -- vapor pressure |
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| low |
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| branching ___ boiling point ____ melting point |
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| decreases BP increases MP |
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| strong intermolecular forces affect __BP __VP __Melting point __surface tension __viscosity |
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| increases all but vapor point |
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| if a cmpd has impurities what would the melting point do? |
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| impurities lower and broaden the range of melting point |
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| normally cmpd has a melting point =120, but you measure your cmpd at 118. Is it the same cmpd? What if you measure 122-125? |
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| 118 yes, just not as pure, thus lower than 120 122-125- no impurities never cause melting point to rise |
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| 3 functional groups that can be removed in acid base extractions in the water layer? |
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| Amines, NH2 Carboxylic acids Phenols |
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| Acid base extraction: want to remove R-NH2 use: |
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| HCL makes it NH3+, polar and therefore in water |
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| Acid base extraction want to remove carboxylic acid use: |
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| NaHCO3 or NaOH |
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| Acid base extraction want to remove phenol use: |
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| NaOH |
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| 3 solvents to come across and the densities |
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| ether (least) water methylene chloride CH2Cl2 (most dense) |
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| how to get rid of ether? |
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| boil it off |
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| how to get rid of the water that now has your charged cmpd in it? |
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| if you added acid to make the cmpd polar and go into the water, use base to make it non-polar again to make it ppt |
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| distillation |
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| Liq w/ LOW BP distill before high BP |
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| thin layer chromatography TLC |
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| seperate via polarity more polar, bottom=low Rf less polar, top =big Rf |
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| TLC, you get super low Rf values, solution: |
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| use more polar solvent to make everything travel further |
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| liquid chromotagraphy |
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| less polar travel first |
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| gas chromotagraphy |
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| seperatation via BP cmpd w/low BP eluted first areas of triangles under peak give abdundances, can calc % |
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| recrystallization |
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| purification due to solubility |
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| solute has __solubility at high temps |
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| high |
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| C+ stability |
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| 3 > 2 > 1 > me |
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| radical stability |
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| 3 > 2 > 1 > me |
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| carbanion stability |
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| Me > 1 > 2 > 3 |
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| SN2 rate |
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| electrophile and nucleophile |
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| SN1 rate |
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| electrophile |
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| solvolysis |
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| SN1 rxn where Nu- is the solvent |
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| 5 polar aprotic solvents to know: |
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| DMSO acetone DMF acetonitrile ethers |
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| what is CH3OH |
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| weak base- SN1/E1 |
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| LG with sp2 C |
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| unreactive aryl and vinyl halides. LG cannot leave |
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| t-bO- |
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| tert butoxide bulky base always E2 |
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| CN- |
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| strong Nu |
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| N3- |
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| strong NU |
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| Cl-, Br, I |
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| strong nu |
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| RS- |
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| strong Nu |
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| HS- |
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| strong NU |
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| R3N |
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| strong Nu |
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| R3P |
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| strong Nu |
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| strong Nu/weak base |
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| SN2 if Me, 1, 2 |
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| strong Nu strong base |
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| E2 and SN2, only for 2 SN2 1 E2 only 3 |
