CHEMISTRY 7405 PAPER 3 CERTIFICATION
SCRIPT 2026 TESTED QUESTIONS AND FULL
SOLUTION
◉ Oxidising Tertiary alcohols. Answer: Tertiary alcohols don't
oxidise
◉ Fehling's Solution. Answer: If a few drops of an aldehyde is added
to Fehling's solution and then gently warmed, the blue solution will
produce a dark red precipitate
◉ Heating under reflux. Answer: When oxidation is intended to be
complete (for a ketone or carboxylic acid) the reactant mixture is
heated under reflux
◉ Distillation with addition. Answer: (Look up apparatus in book)
Is used to obtain an aldehyde as the alcohol is slowly added and as
soon as the aldehyde forms it immediately distills off
◉ Organic vs inorganic apparatus. Answer: -For inorganic
compounds, glassware with corks, bungs and tubing are used
-Organic compounds are flammable, sometimes toxic and can attack
corks and bungs
,-So for organic compounds, chemists use equipment made
predominantly of glass with tight fitting ground glass joints.
◉ Simple Distillation. Answer: -Heat the impure liquid in a flask
connected to a condenser
-The liquid with the lowest boiling temperature evaporates and
condenses first
-A thermometer is used as if the temperature is steady, that is an
indication that one liquid is distilling over. When the temperature
increases again, it has all distilled over
Advantages:
Easier to set up and quicker than fractional distillation
Disadvantages:
It doesn't separate liquids as well as fractional distillation, it should
only be used if the difference in boiling temperatures is larger than
25
◉ Fractional Distillation. Answer: -Same apparatus as simple
distillation but has a fractionating column as well
-The column is filled with glass beads where liquis can condense
again.
,-the water vapour undergoes multiple distillations and so the liquids
are separated more effectively
◉ Solvent extraction with a separating funnel. Answer: -A solvent
that is immiscable with the solvent containing the organic product
and in which the organic product is much more soluble is added
-Place the reaction mixture and the solvent in a separating funnel
-Place the stopper on the neck and shake gently
-Allow two layers to form
-Remove the stopper and open the tap to allow the bottom liquid to
drain out.
However, now the product must be removed from the new solvent
◉ Drying. Answer: -The drying agent (an anhydrous salt) is added to
the mixture, swirled, shaken then left
-The drying agent turns from powdery to crystaline
-If more drying agent remains powdery the liquid is dry
-the drying agent is removed by decantation or filtration
◉ Testing for purity. Answer: -Measure the boiling temperature as
impurities increase the boiling temperature
-The apparatus for a simple distillation can be used
, ◉ Molecular ion peak. Answer: Is the peak created by the molecule.
It is the last large peak
◉ M+1 peak. Answer: The minuscule peak after the molecular ion
peak due to the presence of isotopes (normally carbon 13)
◉ Fragmentation. Answer: Different peaks refer to separate
fragments that have come off the molecule. This can help to identify
a molecule, as some molecules can't form certain fragments
◉ Infrared Spectroscopy. Answer: When molecules absorb infrared
radiation, they vibrate. Different bonds absorb infrared radiations
from different wavelengths in the spectrum, and this can be used to
identify them.
◉ First law of thermodynamics. Answer: During chemical reactions,
energy cannot be created or destroyed, only converted from one
type to another
◉ Enthalpy. Answer: A measure of the total energy of a system
◉ Enthalpy change. Answer: *The heat energy change measured at
constant pressure (ΔH)*
SCRIPT 2026 TESTED QUESTIONS AND FULL
SOLUTION
◉ Oxidising Tertiary alcohols. Answer: Tertiary alcohols don't
oxidise
◉ Fehling's Solution. Answer: If a few drops of an aldehyde is added
to Fehling's solution and then gently warmed, the blue solution will
produce a dark red precipitate
◉ Heating under reflux. Answer: When oxidation is intended to be
complete (for a ketone or carboxylic acid) the reactant mixture is
heated under reflux
◉ Distillation with addition. Answer: (Look up apparatus in book)
Is used to obtain an aldehyde as the alcohol is slowly added and as
soon as the aldehyde forms it immediately distills off
◉ Organic vs inorganic apparatus. Answer: -For inorganic
compounds, glassware with corks, bungs and tubing are used
-Organic compounds are flammable, sometimes toxic and can attack
corks and bungs
,-So for organic compounds, chemists use equipment made
predominantly of glass with tight fitting ground glass joints.
◉ Simple Distillation. Answer: -Heat the impure liquid in a flask
connected to a condenser
-The liquid with the lowest boiling temperature evaporates and
condenses first
-A thermometer is used as if the temperature is steady, that is an
indication that one liquid is distilling over. When the temperature
increases again, it has all distilled over
Advantages:
Easier to set up and quicker than fractional distillation
Disadvantages:
It doesn't separate liquids as well as fractional distillation, it should
only be used if the difference in boiling temperatures is larger than
25
◉ Fractional Distillation. Answer: -Same apparatus as simple
distillation but has a fractionating column as well
-The column is filled with glass beads where liquis can condense
again.
,-the water vapour undergoes multiple distillations and so the liquids
are separated more effectively
◉ Solvent extraction with a separating funnel. Answer: -A solvent
that is immiscable with the solvent containing the organic product
and in which the organic product is much more soluble is added
-Place the reaction mixture and the solvent in a separating funnel
-Place the stopper on the neck and shake gently
-Allow two layers to form
-Remove the stopper and open the tap to allow the bottom liquid to
drain out.
However, now the product must be removed from the new solvent
◉ Drying. Answer: -The drying agent (an anhydrous salt) is added to
the mixture, swirled, shaken then left
-The drying agent turns from powdery to crystaline
-If more drying agent remains powdery the liquid is dry
-the drying agent is removed by decantation or filtration
◉ Testing for purity. Answer: -Measure the boiling temperature as
impurities increase the boiling temperature
-The apparatus for a simple distillation can be used
, ◉ Molecular ion peak. Answer: Is the peak created by the molecule.
It is the last large peak
◉ M+1 peak. Answer: The minuscule peak after the molecular ion
peak due to the presence of isotopes (normally carbon 13)
◉ Fragmentation. Answer: Different peaks refer to separate
fragments that have come off the molecule. This can help to identify
a molecule, as some molecules can't form certain fragments
◉ Infrared Spectroscopy. Answer: When molecules absorb infrared
radiation, they vibrate. Different bonds absorb infrared radiations
from different wavelengths in the spectrum, and this can be used to
identify them.
◉ First law of thermodynamics. Answer: During chemical reactions,
energy cannot be created or destroyed, only converted from one
type to another
◉ Enthalpy. Answer: A measure of the total energy of a system
◉ Enthalpy change. Answer: *The heat energy change measured at
constant pressure (ΔH)*
