OCHEM LAB FINAL EXAM QUESTIONS
AND VERIFIED ANSWERS
\.Why is mp taken? - ANSWERS✔-determination of purity, if range is <2°C
compound is probably pure (unless it is a eutetic temp)
taken for identification of unknown- mixture mp will guaruntee it's the same
\.What happens to mp when there is an impurity? - ANSWERS✔-The mp is
lowered (This does not include glass or salt- their presence will not affect mp)
\.Eutetic temperature - ANSWERS✔-unique mix of A and B that has a sharp mp-
this point is lower than both of their mixture mp other than this specific mix
\.What base will react with protic acids to form the sodium salt of the acid as well
as carbonic acid? - ANSWERS✔-Sodium Bicarbonate (Na HCO3)
\.True or False: compounds the give the same value upon TLC analysis are
definitely the same compound - ANSWERS✔-False
\.True or False: compounds that give different Rf values can be the same
compound - ANSWERS✔-False
, \.What type of reaction is the dehydrohalogenation of alkyl halides? - ANSWERS✔-
E2
\.Zaitsev's rule? What type of reaction? - ANSWERS✔-Most stable compound will
be formed upon E2 reaction
\.Rank the best halogen leaving groups - ANSWERS✔-I > Br > Cl> F
\.When is E2 favored over Sn2? - ANSWERS✔-When a strongly basic, not easily
polarizable reagent is used (ex: hydroxide)
\.Rate of reaction for E2 when comparing tertiary, secondary, and primary -
ANSWERS✔-3 >2 >1
\.Rate of reaction for Sn2 when comparing tertiary, secondary, and primary -
ANSWERS✔-1>2>3
\.Where does the cold water get directed in a reflux apparatus? - ANSWERS✔-The
bottom
\.How far up should the condensation line rise? - ANSWERS✔-Not higher than 1/3
of the way up the condensor
AND VERIFIED ANSWERS
\.Why is mp taken? - ANSWERS✔-determination of purity, if range is <2°C
compound is probably pure (unless it is a eutetic temp)
taken for identification of unknown- mixture mp will guaruntee it's the same
\.What happens to mp when there is an impurity? - ANSWERS✔-The mp is
lowered (This does not include glass or salt- their presence will not affect mp)
\.Eutetic temperature - ANSWERS✔-unique mix of A and B that has a sharp mp-
this point is lower than both of their mixture mp other than this specific mix
\.What base will react with protic acids to form the sodium salt of the acid as well
as carbonic acid? - ANSWERS✔-Sodium Bicarbonate (Na HCO3)
\.True or False: compounds the give the same value upon TLC analysis are
definitely the same compound - ANSWERS✔-False
\.True or False: compounds that give different Rf values can be the same
compound - ANSWERS✔-False
, \.What type of reaction is the dehydrohalogenation of alkyl halides? - ANSWERS✔-
E2
\.Zaitsev's rule? What type of reaction? - ANSWERS✔-Most stable compound will
be formed upon E2 reaction
\.Rank the best halogen leaving groups - ANSWERS✔-I > Br > Cl> F
\.When is E2 favored over Sn2? - ANSWERS✔-When a strongly basic, not easily
polarizable reagent is used (ex: hydroxide)
\.Rate of reaction for E2 when comparing tertiary, secondary, and primary -
ANSWERS✔-3 >2 >1
\.Rate of reaction for Sn2 when comparing tertiary, secondary, and primary -
ANSWERS✔-1>2>3
\.Where does the cold water get directed in a reflux apparatus? - ANSWERS✔-The
bottom
\.How far up should the condensation line rise? - ANSWERS✔-Not higher than 1/3
of the way up the condensor
