AQA A LEVEL CHEMISTRY EXAM 2024 mean bond enthalpy - ANSWER -The e nergy 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 subject ed 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 it s 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 Relative atomic mass - ANSWER -The average mass of an atom of an element, relative to 1/12th of the mass of an atom of Carbon -12 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 Lattice enthalpy of dissociation - ANSWER -Energy chang e when 1 mol of an ionic lattice dissociates to its gaseous ions. standard electrode potential - ANSWER -298K 100kPa 1.00moldm -3 Electrode reactions in lithium cell (positive electrode) - ANSWER -Li+ + CoO2 + e - → Li+[CoO2] - Electrode reactions in lithi um cell (negative electrode) - ANSWER -Li → Li+ + e - Oxidation of primary alcohols - ANSWER -Aldehyde (Alcohol in excess + product distilled off immediately) Carboxylic acid (oxidising agent in excess + Under reflux ) Oxidation of secondary alcohols - ANSWER -Ketones No further oxidati on
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 Lattice enthalpy of dissociation - ANSWER -Energy chang e when 1 mol of an ionic lattice dissociates to its gaseous ions. standard electrode potential - ANSWER -298K 100kPa 1.00moldm -3 Electrode reactions in lithium cell (positive electrode) - ANSWER -Li+ + CoO2 + e - → Li+[CoO2] - Electrode reactions in lithi um cell (negative electrode) - ANSWER -Li → Li+ + e - Oxidation of primary alcohols - ANSWER -Aldehyde (Alcohol in excess + product distilled off immediately) Carboxylic acid (oxidising agent in excess + Under reflux ) Oxidation of secondary alcohols - ANSWER -Ketones No further oxidati on
