A Level Chemistry Paper 3 ( Practical Skills) – Exam Questions Model Answers
and Mark Scheme ( A+ Guide)
Activation Energy - ✔✔✔-The minimum energy that colliding particles must possess for a
reaction to occur
Addition of Hydrogen Halides - ✔✔✔-Hydrogen halides are added under no specific conditions
and form a halogenoalkene
Addition reaction to form a Polymer - ✔✔✔-
Addition reactions of Alkenes - ✔✔✔--Hydrogenation
-Halogenation
-Hydration
-Addition of hydrogen halides
- Oxidation to diols
Alcohols - ✔✔✔-A homologous series of compounds with general formula CnH2n+1OH
They can be classified as primary secondary and tertiary as well
Alcohols to Halogenoalkanes:
Bromination - ✔✔✔-First equation (inorganic products)
-Uses potassium bromide and 50% concentrated concentrated sulfuric acid
-Forms HBr and Potassium sulfate or potassium hydrogen sulfate.
KBr + H2SO4 -> KHSO4 + HBr
or
KBr + H2SO4 -> K2SO4 + HBr
Second equation:
,A Level Chemistry Paper 3 ( Practical Skills) – Exam Questions Model Answers
and Mark Scheme ( A+ Guide)
-CH3CH2OH + HBr -> CH3CH2Br + H2O
Alcohols to Halogenoalkanes:
Chlorination - ✔✔✔-For Primary and Secondary Alcohols:
-Phosphorus(v) chloride is used (PCl5)
-Reaction is vigorous so no heating required
-Products are POCl3, HCl and a chloroalkane
Equation:
CH3CH2CH2OH + PCl5 -> CH3CH2CH2Cl + POCl3 + HCl
For Tertiary Alcohols:
-Alcohol is shaken at room temperature with concentrated HCl
-Products are chloroalkane and water
Equation:
(CH3)3COH + HCl -> (CH3)3CCl + H2O
Alcohols to Halogenoalkanes:
Iodination - ✔✔✔--Uses red phosphorous and iodine
-The reaction mixture is heated under reflux
Inorganic Equation:
2P + 3I2 -> 2PI3
Organic Equation:
3C2H5OH + PI3 -> 3C2H5I + H3PO3
,A Level Chemistry Paper 3 ( Practical Skills) – Exam Questions Model Answers
and Mark Scheme ( A+ Guide)
The inorganic product is phosphonic acid
Alkanes - ✔✔✔-Saturated hydrocarbons with the general formula CnH2n+2
Alkenes - ✔✔✔-Alkenes are a homologous series of saturated hydrocarbons with a general
formula of CnH2n (CnH2n-2 for cycloalkenes)
Ammonia solution and Halogenoalkanes - ✔✔✔-- The ammonia molecule (the lone electron
pair on it) is the attacking nucleophile
- The product is a primary amine
- The NH3 attaches itself to the organic compound first, creating an ion (because the halogen
has taken the electrons from the C-X bond) , then an H+ from this ion reacts another ammonia
molecule to form an ammonium ion
Atom economy - ✔✔✔-Atom economy looks at the the percentage of the molar mass of the
products that ends up in the reactants.
molar mass of desired product / sum of molar masses of products
x 100%
Atomic emission spectra - ✔✔✔-When atoms absorb energy (either heat or electrical) the
electrons are exited and move up a quantum level before returning to the ground state. The
energy is released as electromagnetic radiation. The spectra of this radiation is unique for every
atom, as it requires differing amounts of energy to excite electrons of different atoms because
there are only specific quantum shells that they can go to. Otherwise the frequency would be
continuous.
Atomic Number - ✔✔✔-*The number of protons in an atom. An atom will have the same
number of electrons*
, A Level Chemistry Paper 3 ( Practical Skills) – Exam Questions Model Answers
and Mark Scheme ( A+ Guide)
Aufbau Principle - ✔✔✔-Electrons will fill lower energy subshells first (hence they fill 4s
subshell before the 3 subshell)
Avogadro constant - ✔✔✔--shown as L
6.02 x 10^23
-units are mol-1
Barium Meals - ✔✔✔-Barium sulphate is given to patients so that softer tissues show up on an
x-ray. Barium ions are harmful to humans, but as barium sulphate is insoluble, the ions are not
free to move
Bioalchohols - ✔✔✔-Can be produced by the fermentation of sugar, but there's a limit to the
ethanol concentration of fermentation, so the ethanol has to be separated from a lot of water
(which takes energy) before it can be used.
Bioethanol is now produced with bacteria rather than enzymes, which has a higher yield of
ethanol for a smaller starting amount.
Biodegradable polymers - ✔✔✔-Polymers can be manufactured to break down by microbes
and the environment.
However this uses plant materials (which could be used for food)
Biodiesel - ✔✔✔-Biodeisel is made from vegetable oils (such as rapeseed of sunflower oil) and
can be mixed with normal diesel as well
Biodiesels vs Natural Gas:
Natural Gas - ✔✔✔-Land use:
No land needed
Yield:
and Mark Scheme ( A+ Guide)
Activation Energy - ✔✔✔-The minimum energy that colliding particles must possess for a
reaction to occur
Addition of Hydrogen Halides - ✔✔✔-Hydrogen halides are added under no specific conditions
and form a halogenoalkene
Addition reaction to form a Polymer - ✔✔✔-
Addition reactions of Alkenes - ✔✔✔--Hydrogenation
-Halogenation
-Hydration
-Addition of hydrogen halides
- Oxidation to diols
Alcohols - ✔✔✔-A homologous series of compounds with general formula CnH2n+1OH
They can be classified as primary secondary and tertiary as well
Alcohols to Halogenoalkanes:
Bromination - ✔✔✔-First equation (inorganic products)
-Uses potassium bromide and 50% concentrated concentrated sulfuric acid
-Forms HBr and Potassium sulfate or potassium hydrogen sulfate.
KBr + H2SO4 -> KHSO4 + HBr
or
KBr + H2SO4 -> K2SO4 + HBr
Second equation:
,A Level Chemistry Paper 3 ( Practical Skills) – Exam Questions Model Answers
and Mark Scheme ( A+ Guide)
-CH3CH2OH + HBr -> CH3CH2Br + H2O
Alcohols to Halogenoalkanes:
Chlorination - ✔✔✔-For Primary and Secondary Alcohols:
-Phosphorus(v) chloride is used (PCl5)
-Reaction is vigorous so no heating required
-Products are POCl3, HCl and a chloroalkane
Equation:
CH3CH2CH2OH + PCl5 -> CH3CH2CH2Cl + POCl3 + HCl
For Tertiary Alcohols:
-Alcohol is shaken at room temperature with concentrated HCl
-Products are chloroalkane and water
Equation:
(CH3)3COH + HCl -> (CH3)3CCl + H2O
Alcohols to Halogenoalkanes:
Iodination - ✔✔✔--Uses red phosphorous and iodine
-The reaction mixture is heated under reflux
Inorganic Equation:
2P + 3I2 -> 2PI3
Organic Equation:
3C2H5OH + PI3 -> 3C2H5I + H3PO3
,A Level Chemistry Paper 3 ( Practical Skills) – Exam Questions Model Answers
and Mark Scheme ( A+ Guide)
The inorganic product is phosphonic acid
Alkanes - ✔✔✔-Saturated hydrocarbons with the general formula CnH2n+2
Alkenes - ✔✔✔-Alkenes are a homologous series of saturated hydrocarbons with a general
formula of CnH2n (CnH2n-2 for cycloalkenes)
Ammonia solution and Halogenoalkanes - ✔✔✔-- The ammonia molecule (the lone electron
pair on it) is the attacking nucleophile
- The product is a primary amine
- The NH3 attaches itself to the organic compound first, creating an ion (because the halogen
has taken the electrons from the C-X bond) , then an H+ from this ion reacts another ammonia
molecule to form an ammonium ion
Atom economy - ✔✔✔-Atom economy looks at the the percentage of the molar mass of the
products that ends up in the reactants.
molar mass of desired product / sum of molar masses of products
x 100%
Atomic emission spectra - ✔✔✔-When atoms absorb energy (either heat or electrical) the
electrons are exited and move up a quantum level before returning to the ground state. The
energy is released as electromagnetic radiation. The spectra of this radiation is unique for every
atom, as it requires differing amounts of energy to excite electrons of different atoms because
there are only specific quantum shells that they can go to. Otherwise the frequency would be
continuous.
Atomic Number - ✔✔✔-*The number of protons in an atom. An atom will have the same
number of electrons*
, A Level Chemistry Paper 3 ( Practical Skills) – Exam Questions Model Answers
and Mark Scheme ( A+ Guide)
Aufbau Principle - ✔✔✔-Electrons will fill lower energy subshells first (hence they fill 4s
subshell before the 3 subshell)
Avogadro constant - ✔✔✔--shown as L
6.02 x 10^23
-units are mol-1
Barium Meals - ✔✔✔-Barium sulphate is given to patients so that softer tissues show up on an
x-ray. Barium ions are harmful to humans, but as barium sulphate is insoluble, the ions are not
free to move
Bioalchohols - ✔✔✔-Can be produced by the fermentation of sugar, but there's a limit to the
ethanol concentration of fermentation, so the ethanol has to be separated from a lot of water
(which takes energy) before it can be used.
Bioethanol is now produced with bacteria rather than enzymes, which has a higher yield of
ethanol for a smaller starting amount.
Biodegradable polymers - ✔✔✔-Polymers can be manufactured to break down by microbes
and the environment.
However this uses plant materials (which could be used for food)
Biodiesel - ✔✔✔-Biodeisel is made from vegetable oils (such as rapeseed of sunflower oil) and
can be mixed with normal diesel as well
Biodiesels vs Natural Gas:
Natural Gas - ✔✔✔-Land use:
No land needed
Yield:
