AQA A LEVEL CHEMISTRY PAPER 1 7405
QUESTIONS AND SOLUTIONS GRADED A+
◉ Relative molecular mass. Answer: Average mass of a molecule
compared to 1/12th of the mass of a carbon-12 atom
◉ The Avogradro constant. Answer: the number of particles in a
mole
◉ ideal gas equation. Answer: pV = nRT
◉ empirical formula. Answer: the simplest whole number ratio of
atoms of each element in a compound
◉ percentage atom economy. Answer: (Mass of desired
product/total mass of reactants) x 100
◉ ionic bonding. Answer: the electrostatic attraction between
oppositely charged ions in a lattice
◉ covalent bond. Answer: a shared pair of electrons between non-
metal elements
,◉ co-ordinate bond. Answer: a shared pair of electrons where both
electrons are supplied by one atom
◉ repulsion in shapes of molecules. Answer: Lone pair-lone pair >
lone pair-bonding pair > bonding pair-bonding pair
◉ electronegativity. Answer: the power of an atom to attract the pair
of electrons in a covalent bond
◉ hess' law. Answer: Total enthalpy change for a reaction is
independent of the route chosen
◉ mean bond enthalpy. Answer: The energy required to break a
covalent bond into gaseous atoms averaged over different molecules
Bonds broken - bonds made
◉ activation energy. Answer: The minimum amount of energy
needed to start a chemical reaction
◉ catalyst. Answer: A substance that increases the rate of a chemical
reaction without being changed by providing an alternative reaction
pathway by lowering activation energy
, ◉ Le Chatelier's principle. Answer: When a system in dynamic
equilibrium is subjected to change, the position of equilibrium will
shift to oppose the change.
◉ oxidising agents. Answer: electron acceptors
◉ reducing agents. Answer: electron donors
◉ Enthalpy of formation. Answer: Enthalpy change when one mole
of a compound is formed from its constituent elements under
standard conditions in their standard states
◉ Enthalpy of atomization. Answer: The energy required to produce
one mole of gaseous atoms from an element in its standard state
◉ Electron affinity. Answer: the enthaply change when one mole of
gaseous atoms forms one mole of -1 ions
◉ Lattice enthalpy of formation. Answer: Enthalpy change when one
mole of a solid ionic compound is formed from its constituent ions in
the gas phase
QUESTIONS AND SOLUTIONS GRADED A+
◉ Relative molecular mass. Answer: Average mass of a molecule
compared to 1/12th of the mass of a carbon-12 atom
◉ The Avogradro constant. Answer: the number of particles in a
mole
◉ ideal gas equation. Answer: pV = nRT
◉ empirical formula. Answer: the simplest whole number ratio of
atoms of each element in a compound
◉ percentage atom economy. Answer: (Mass of desired
product/total mass of reactants) x 100
◉ ionic bonding. Answer: the electrostatic attraction between
oppositely charged ions in a lattice
◉ covalent bond. Answer: a shared pair of electrons between non-
metal elements
,◉ co-ordinate bond. Answer: a shared pair of electrons where both
electrons are supplied by one atom
◉ repulsion in shapes of molecules. Answer: Lone pair-lone pair >
lone pair-bonding pair > bonding pair-bonding pair
◉ electronegativity. Answer: the power of an atom to attract the pair
of electrons in a covalent bond
◉ hess' law. Answer: Total enthalpy change for a reaction is
independent of the route chosen
◉ mean bond enthalpy. Answer: The energy required to break a
covalent bond into gaseous atoms averaged over different molecules
Bonds broken - bonds made
◉ activation energy. Answer: The minimum amount of energy
needed to start a chemical reaction
◉ catalyst. Answer: A substance that increases the rate of a chemical
reaction without being changed by providing an alternative reaction
pathway by lowering activation energy
, ◉ Le Chatelier's principle. Answer: When a system in dynamic
equilibrium is subjected to change, the position of equilibrium will
shift to oppose the change.
◉ oxidising agents. Answer: electron acceptors
◉ reducing agents. Answer: electron donors
◉ Enthalpy of formation. Answer: Enthalpy change when one mole
of a compound is formed from its constituent elements under
standard conditions in their standard states
◉ Enthalpy of atomization. Answer: The energy required to produce
one mole of gaseous atoms from an element in its standard state
◉ Electron affinity. Answer: the enthaply change when one mole of
gaseous atoms forms one mole of -1 ions
◉ Lattice enthalpy of formation. Answer: Enthalpy change when one
mole of a solid ionic compound is formed from its constituent ions in
the gas phase
