AQA Chemistry A-Level Markscheme
Flashcards Questions With Correct
Answers
Define the term relative atomic mass (2 marks). - Correct Answer - .1. The average
mass of an atom of an element
(average mass of all isotopes of an element)
2. Compared to 1/12th the mass of an atom of carbon-12
Describe how molecules are ionised using electrospray ionisation (4 marks). - Correct
Answer - 1. Sample dissolved (in a volatile solvent)
(allow named solvent eg water or methanol)
2. (injected through) a needle or nozzle or capillary and at high voltage/4000 volts or
high potential
(allow needle is positively charged)
3. Gains a proton / H+
4. X + H+ → XH+
Outline how the TOF mass spectrometer works (4 marks). - Correct Answer - 1. Positive
ions are accelerated by an electric field
(allow (ions) accelerated to a negative plate)
2. To a constant kinetic energy
3. Ions create a current when hitting the detector
4. The size of the current is proportional to the abundance of ions hitting the plate and
gaining an electron
The student rinses the burette with deionised water before filling with
sodium hydroxide solution.
State and explain the effect, if any, that this rinsing will have on the value of
the titre (2 marks). - Correct Answer - 1. Titre value would increase / larger value
2. Because the sodium hydroxide solution would be more dilute
The student used a wash bottle containing deionised water when
approaching the end-point to rinse the inside of the conical flask.
Explain why this improved the accuracy of the titration (1 mark). - Correct Answer - 1.
Idea that it ensures all ethanedioic acid / acid / sodium hydroxide / alkali / reactants are
in the mixture / solution / reaction
OR
the idea that some of the ethanedioic acid / acid / sodium hydroxide / alkali / reactants
would be on the sides of the flask
, Explain why pentan-2-ol has a higher boiling point than pent-1-ene (3 marks). - Correct
Answer - 1. Pentan-2-ol has stronger intermolecular forces
2. Pent-1-ene has van der Waals' forces (only)
3. Pentan-2-ol (also) has hydrogen bonds
Explain why a fluoride ion is larger than a sodium ion (2 marks). - Correct Answer - 1.
Fluoride ion has (two) fewer protons/lower nuclear charge
2. Weaker attraction between nucleus and (outer) electrons
Explain, in terms of structure and bonding, why the melting point of sodium fluoride is
high (2 marks). - Correct Answer - 1. (Electrostatic) forces of attraction between
oppositely charged ions/Na+ and F-
2. Lots of energy needed to overcome/break forces
Explain how the lone pairs of electrons on the oxygen atom influence the
bond angle in oxygen difluoride (2 marks). - Correct Answer - 1. Lone pairs repel more
than bond pairs
2. Bond angle will be lower than regular tetrahedral angle
Explain how permanent dipole-dipole forces arise between hydrogen
chloride molecules (2 marks). - Correct Answer - 1. Difference in electronegativity leads
to bond polarity
2. And there is an attraction between delta positive on one molecule and delta negative
on another
Explain how the intermolecular forces arise between molecules of chlorine (3 marks). -
Correct Answer - 1. (Random) movement of electrons in one molecule (creates a
dipole)/ a (temporary) dipole is formed in one molecule
2. Induces a dipole a neighbouring molecule
3. (These) temporary dipoles attract/temporary attraction between delta positive and
delta negative
Explain, in terms of crystal structure and bonding, why silicon (IV) oxide has a higher
melting point than phosphorus (V) oxide (4 marks). - Correct Answer - 1. SiO2 is
macromolecular
2. Strong covalent bonds (between atoms)
3. P4O10 is molecular or simple covalent
4. Weak van der Waals forces between molecules
Define the term enthalpy change (1 mark). - Correct Answer - 1. Heat (energy) change
at constant pressure
Define the term mean bond enthalpy (2 marks). - Correct Answer - 1. Average enthalpy
change when one mole of gaseous molecules
2. Breaks a covalent bond to form two free radicals
Flashcards Questions With Correct
Answers
Define the term relative atomic mass (2 marks). - Correct Answer - .1. The average
mass of an atom of an element
(average mass of all isotopes of an element)
2. Compared to 1/12th the mass of an atom of carbon-12
Describe how molecules are ionised using electrospray ionisation (4 marks). - Correct
Answer - 1. Sample dissolved (in a volatile solvent)
(allow named solvent eg water or methanol)
2. (injected through) a needle or nozzle or capillary and at high voltage/4000 volts or
high potential
(allow needle is positively charged)
3. Gains a proton / H+
4. X + H+ → XH+
Outline how the TOF mass spectrometer works (4 marks). - Correct Answer - 1. Positive
ions are accelerated by an electric field
(allow (ions) accelerated to a negative plate)
2. To a constant kinetic energy
3. Ions create a current when hitting the detector
4. The size of the current is proportional to the abundance of ions hitting the plate and
gaining an electron
The student rinses the burette with deionised water before filling with
sodium hydroxide solution.
State and explain the effect, if any, that this rinsing will have on the value of
the titre (2 marks). - Correct Answer - 1. Titre value would increase / larger value
2. Because the sodium hydroxide solution would be more dilute
The student used a wash bottle containing deionised water when
approaching the end-point to rinse the inside of the conical flask.
Explain why this improved the accuracy of the titration (1 mark). - Correct Answer - 1.
Idea that it ensures all ethanedioic acid / acid / sodium hydroxide / alkali / reactants are
in the mixture / solution / reaction
OR
the idea that some of the ethanedioic acid / acid / sodium hydroxide / alkali / reactants
would be on the sides of the flask
, Explain why pentan-2-ol has a higher boiling point than pent-1-ene (3 marks). - Correct
Answer - 1. Pentan-2-ol has stronger intermolecular forces
2. Pent-1-ene has van der Waals' forces (only)
3. Pentan-2-ol (also) has hydrogen bonds
Explain why a fluoride ion is larger than a sodium ion (2 marks). - Correct Answer - 1.
Fluoride ion has (two) fewer protons/lower nuclear charge
2. Weaker attraction between nucleus and (outer) electrons
Explain, in terms of structure and bonding, why the melting point of sodium fluoride is
high (2 marks). - Correct Answer - 1. (Electrostatic) forces of attraction between
oppositely charged ions/Na+ and F-
2. Lots of energy needed to overcome/break forces
Explain how the lone pairs of electrons on the oxygen atom influence the
bond angle in oxygen difluoride (2 marks). - Correct Answer - 1. Lone pairs repel more
than bond pairs
2. Bond angle will be lower than regular tetrahedral angle
Explain how permanent dipole-dipole forces arise between hydrogen
chloride molecules (2 marks). - Correct Answer - 1. Difference in electronegativity leads
to bond polarity
2. And there is an attraction between delta positive on one molecule and delta negative
on another
Explain how the intermolecular forces arise between molecules of chlorine (3 marks). -
Correct Answer - 1. (Random) movement of electrons in one molecule (creates a
dipole)/ a (temporary) dipole is formed in one molecule
2. Induces a dipole a neighbouring molecule
3. (These) temporary dipoles attract/temporary attraction between delta positive and
delta negative
Explain, in terms of crystal structure and bonding, why silicon (IV) oxide has a higher
melting point than phosphorus (V) oxide (4 marks). - Correct Answer - 1. SiO2 is
macromolecular
2. Strong covalent bonds (between atoms)
3. P4O10 is molecular or simple covalent
4. Weak van der Waals forces between molecules
Define the term enthalpy change (1 mark). - Correct Answer - 1. Heat (energy) change
at constant pressure
Define the term mean bond enthalpy (2 marks). - Correct Answer - 1. Average enthalpy
change when one mole of gaseous molecules
2. Breaks a covalent bond to form two free radicals
