CHEM 232 Final Test with Complete
Solutions
distillation - ANS-a process in which a liquid is heated to its boiling point and the
resulting vapor phase is conducted to and condensed in a different container
separation and purification technique for a mixture of liquids that have different boiling
points
types of distillation - ANS-simple and fractional
boiling point - ANS-occurs when the vapor pressure of the liquid being heated is equal
to the external pressure, in most cases 760 mmHg, this is normal boiling point
Simple distillation - ANS-A useful technique for when the liquids in the mixture have ~50
C difference in their boiling point
Fractional distillation - ANS-separation of a liquid mixture into fractions differing in
boiling point (and hence chemical composition) by means of distillation, typically using a
fractionating column.
fractionating column - ANS-the vertical column which is used to bring about the
separation of liquids in fractional distillation, has beads in it and makes the repeated
distillations possible.
The fractionating column is filled with packing materials providing surface area for
repeated vaporizations and condensations to take place before collecting the final
product
The spinach pigments would just decompose
How to follow free radical halogenation of alkanes experiment - ANS-the red/orange
bromine color and when this disappeared it signifies Br2 has been totally consumed
6 hydrocarbons tested in free radical halogenation of alkanes experiment - ANS-toluene
ethylbenzene
isopropylbenzene
, t-butylbenzene
cyclohexane
methylcyclohexane
three tests in free radical halogenation of alkanes experiment - ANS-Part A: Bromination
at room temperature
Part B: Bromination at an elevated temperature
Part C: bromination with irradiation (light)
purpose of free radical bromination - ANS-substitute a Br for a hydrogen in a
hydrocarbon
The initial Br radicals are formed because - ANS-the sigma C-C bonds in the
hydrocarbon donate a single electron to the bromine
order of stability - ANS-benzylic < 1 < 2 < 2 < aryl
order of reactivity - ANS-cyclohexane < methylcyclohexane < toluene < ethylbenzene <
isopropylbenzene < methylcyclohexane
When bromine is first added to the hydrocarbon solution, the color will be -
ANS-red/orange
When the bromine has reacted with they hydrocarbon, the solution will - ANS-be clear
if no reaction occurs - ANS-remain red/orange
why is substitution reaction in competition with elimination rxn - ANS-ucleophile can act
as a base or as a nucleophile
Conductivity Detector - ANS-Since the leaving group in a substitution rxn is often
negatively charged ion, the conductivity detector can be utilized to indicate that a
reaction is taking place
reflux - ANS-use this technique in order to heat the reaction at the solvents boiling point
without boiling it off by using a condenser.
the condenser has an inner tube where the vapor rises and an outer tube that as water
running through it, cooling the walls of the condenser
As the vapor touches the cooled walls of the condenser, they lose heat and condense
back into liquid phase dropping down into the rxn flask
Solutions
distillation - ANS-a process in which a liquid is heated to its boiling point and the
resulting vapor phase is conducted to and condensed in a different container
separation and purification technique for a mixture of liquids that have different boiling
points
types of distillation - ANS-simple and fractional
boiling point - ANS-occurs when the vapor pressure of the liquid being heated is equal
to the external pressure, in most cases 760 mmHg, this is normal boiling point
Simple distillation - ANS-A useful technique for when the liquids in the mixture have ~50
C difference in their boiling point
Fractional distillation - ANS-separation of a liquid mixture into fractions differing in
boiling point (and hence chemical composition) by means of distillation, typically using a
fractionating column.
fractionating column - ANS-the vertical column which is used to bring about the
separation of liquids in fractional distillation, has beads in it and makes the repeated
distillations possible.
The fractionating column is filled with packing materials providing surface area for
repeated vaporizations and condensations to take place before collecting the final
product
The spinach pigments would just decompose
How to follow free radical halogenation of alkanes experiment - ANS-the red/orange
bromine color and when this disappeared it signifies Br2 has been totally consumed
6 hydrocarbons tested in free radical halogenation of alkanes experiment - ANS-toluene
ethylbenzene
isopropylbenzene
, t-butylbenzene
cyclohexane
methylcyclohexane
three tests in free radical halogenation of alkanes experiment - ANS-Part A: Bromination
at room temperature
Part B: Bromination at an elevated temperature
Part C: bromination with irradiation (light)
purpose of free radical bromination - ANS-substitute a Br for a hydrogen in a
hydrocarbon
The initial Br radicals are formed because - ANS-the sigma C-C bonds in the
hydrocarbon donate a single electron to the bromine
order of stability - ANS-benzylic < 1 < 2 < 2 < aryl
order of reactivity - ANS-cyclohexane < methylcyclohexane < toluene < ethylbenzene <
isopropylbenzene < methylcyclohexane
When bromine is first added to the hydrocarbon solution, the color will be -
ANS-red/orange
When the bromine has reacted with they hydrocarbon, the solution will - ANS-be clear
if no reaction occurs - ANS-remain red/orange
why is substitution reaction in competition with elimination rxn - ANS-ucleophile can act
as a base or as a nucleophile
Conductivity Detector - ANS-Since the leaving group in a substitution rxn is often
negatively charged ion, the conductivity detector can be utilized to indicate that a
reaction is taking place
reflux - ANS-use this technique in order to heat the reaction at the solvents boiling point
without boiling it off by using a condenser.
the condenser has an inner tube where the vapor rises and an outer tube that as water
running through it, cooling the walls of the condenser
As the vapor touches the cooled walls of the condenser, they lose heat and condense
back into liquid phase dropping down into the rxn flask
