CHEM232 Final Exam with Accurate
Solutions
distillation lab 6 - ANS-used cyclohexane and toluene
distillation - ANS-separation and purification technique for a mixture of liquids that have
different boiling points
boiling point - ANS-when the vapor pressure of the liquid being heated reaches the
external pressure
when atmospheric pressure is reduced, BP is reduced
for every 10mmHg decrease in pressure there is a .0.5 degree Celsius decrease in BP
simple distillation is good for ... - ANS-liquid mixtures in which the liquids have at least a
100 degree Celsius difference in their BP
when the mixture is 90% one substance and 10% the other
when the liquid mixture contains a pure substance and a non-volatile solid (solids that
won't easily vaporize)
difference between distilling a pure liquid and distilling a mixed liquid - ANS-when
distilling a pure liquid the temp. will remain constant
when distilling a liquid mixture the temp. will gradually increase because as the liquid
with lower BP vaporizes the composition of the liquid mixture is changing and the % that
is the liquid with higher BP is increasing
Fractional distillation - ANS-uses a fractioning column
has many theoretical plates because the fractioning column has tons of glass beads
inside that allow for more surface area for condensation of the vaporized liquid
creates a temperature gradient where the temp. at the bottom of the column is high and
at the top is low
at the point where all of the liquid wit lower BP is distilled the temp. will drop - we then
need to increase temp. so we can distill the liquid that has higher BP
temperature gradient - ANS-crucial for successful distillation because if the temp. falls
below BP the liquid will drip back down the column
high temp. on bottom
low temp. at top
, created by insulating the column and a maintaining the heat
we know we've run out of the liquid that has lower BP when... - ANS-temp. decreases
which is more exothermic during free radical halogenation - bromine or chlorine? - ANS-
chlorine
we can control the experiment better when using bromine
nucleophilic substitution reactions lab 9 - ANS-used a conductivity detector to test the
strength of electrolytes (solutions that contain ions and conduct electricity)
red light - weak electrolyte
red and green light - strong electrolyte
larger atoms are more (stable/unstable) and are (better/worse) leaving groups - ANS-
stable - cuz of charge distribution
better - they're fine on their own
leaving group - ANS-a weak conjugate base of a strong acid
which reacts faster, a primary or secondary alkyl halide? - ANS-primary - the site is less
crowded so backside attack can occur
reflux - ANS-allows us to run the reaction at the solvent's BP with without boiling it off
the condenser has in inner tube (where the vapor rises) and an outer tube through
which water runs and cools the condenser - as vapor touches the walls of the
condenser it makes the vapor condense back into liquid
good reflux has the drops falling back into theflask at 1 drop per second
which type of reaction conditions increases the ratio of substitution to elimination? -
ANS-primary alkyl halide
conductivity probe - ANS-measure the formation of Br- / Cl- anions that are byproducts
pf the reaction
alkyl halide rate of reaction - ANS-primary alkyl halides react faster than secondary alkyl
halides
alkyl bromide reacts faster than alkyl chloride (it is larger and more stable)
Solutions
distillation lab 6 - ANS-used cyclohexane and toluene
distillation - ANS-separation and purification technique for a mixture of liquids that have
different boiling points
boiling point - ANS-when the vapor pressure of the liquid being heated reaches the
external pressure
when atmospheric pressure is reduced, BP is reduced
for every 10mmHg decrease in pressure there is a .0.5 degree Celsius decrease in BP
simple distillation is good for ... - ANS-liquid mixtures in which the liquids have at least a
100 degree Celsius difference in their BP
when the mixture is 90% one substance and 10% the other
when the liquid mixture contains a pure substance and a non-volatile solid (solids that
won't easily vaporize)
difference between distilling a pure liquid and distilling a mixed liquid - ANS-when
distilling a pure liquid the temp. will remain constant
when distilling a liquid mixture the temp. will gradually increase because as the liquid
with lower BP vaporizes the composition of the liquid mixture is changing and the % that
is the liquid with higher BP is increasing
Fractional distillation - ANS-uses a fractioning column
has many theoretical plates because the fractioning column has tons of glass beads
inside that allow for more surface area for condensation of the vaporized liquid
creates a temperature gradient where the temp. at the bottom of the column is high and
at the top is low
at the point where all of the liquid wit lower BP is distilled the temp. will drop - we then
need to increase temp. so we can distill the liquid that has higher BP
temperature gradient - ANS-crucial for successful distillation because if the temp. falls
below BP the liquid will drip back down the column
high temp. on bottom
low temp. at top
, created by insulating the column and a maintaining the heat
we know we've run out of the liquid that has lower BP when... - ANS-temp. decreases
which is more exothermic during free radical halogenation - bromine or chlorine? - ANS-
chlorine
we can control the experiment better when using bromine
nucleophilic substitution reactions lab 9 - ANS-used a conductivity detector to test the
strength of electrolytes (solutions that contain ions and conduct electricity)
red light - weak electrolyte
red and green light - strong electrolyte
larger atoms are more (stable/unstable) and are (better/worse) leaving groups - ANS-
stable - cuz of charge distribution
better - they're fine on their own
leaving group - ANS-a weak conjugate base of a strong acid
which reacts faster, a primary or secondary alkyl halide? - ANS-primary - the site is less
crowded so backside attack can occur
reflux - ANS-allows us to run the reaction at the solvent's BP with without boiling it off
the condenser has in inner tube (where the vapor rises) and an outer tube through
which water runs and cools the condenser - as vapor touches the walls of the
condenser it makes the vapor condense back into liquid
good reflux has the drops falling back into theflask at 1 drop per second
which type of reaction conditions increases the ratio of substitution to elimination? -
ANS-primary alkyl halide
conductivity probe - ANS-measure the formation of Br- / Cl- anions that are byproducts
pf the reaction
alkyl halide rate of reaction - ANS-primary alkyl halides react faster than secondary alkyl
halides
alkyl bromide reacts faster than alkyl chloride (it is larger and more stable)
