AQA A LEVEL Chemistry questions and solutions

AQA A LEVEL Chemistry questions and solutions

Relative atomic mass - answersThe average mass of an atom of an element, relative to 1/12th of the mass of an atom of
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Carbon-12
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Relative molecular mass - answersAverage mass of a molecule compared to 1/12th of the mass of a carbon-12 atom
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The Avogradro constant - answersthe number of particles in a mole
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ideal gas equation - answerspV = nRT
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empirical formula - answersthe simplest whole number ratio of atoms of each element in a compound
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percentage atom economy - answers(Mass of desired product/total mass of reactants) x 100 ro ro ro ro ro ro ro ro ro ro ro ro




ionic bonding - answersthe electrostatic attraction between oppositely charged ions in a lattice
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covalent bond - answersa shared pair of electrons between non-metal elements
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co-ordinate bond - answersa shared pair of electrons where both electrons are supplied by one atomro ro ro ro ro ro ro ro ro ro ro ro ro ro ro




repulsion in shapes of molecules - answersLone pair-lone pair > lone pair-bonding pair > bonding pair-bonding pair
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electronegativity - answersthe power of an atom to attract the pair of electrons in a covalent bond ro ro ro ro ro ro ro ro ro ro ro ro ro ro ro ro




hess' law - answersTotal enthalpy change for a reaction is independent of the route chosen
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mean bond enthalpy - answersThe energy required to break a covalent bond into gaseous atoms averaged over differen
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molecules
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Bonds broken - bonds made ro ro ro ro




activation energy - answersThe minimum amount of energy needed to start a chemical reaction
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catalyst - answersA substance that increases the rate of a chemical reaction without being changed by providing an
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alternative reaction pathway by lowering activation energy
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Le Chatelier's principle - answersWhen a system in dynamic equilibrium is subjected to change, the position of equilibriu
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will shift to oppose the change.
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oxidising agents - answerselectron acceptors ro ro ro ro




reducing agents - answerselectron donors ro ro ro ro




Enthalpy of formation - answersEnthalpy change when one mole of a compound is formed from its constituent elements
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under standard conditions in their standard states
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,Enthalpy of atomization - answersThe energy required to produce one mole of gaseous atoms from an element in its
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standard state
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Electron affinity - answersthe enthaply change when one mole of gaseous atoms forms one mole of -1 ions
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Lattice enthalpy of formation - answersEnthalpy change when one mole of a solid ionic compound is formed from its
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constituent ions in the gas phase
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Lattice enthalpy of dissociation - answersEnergy change when 1 mol of an ionic lattice dissociates to its gaseous ions.
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standard electrode potential - answers298K ro ro ro ro ro




100kPa
1.00moldm-3

Electrode reactions in lithium cell ro ro ro ro




(positive electrode) - answersLi+ + CoO2 + e- → Li+[CoO2]-
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Electrode reactions in lithium cell ro ro ro ro




(negative electrode) - answersLi → Li+ + e-
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Electrode reactions in hydrogen-oxygen fuel cell in acidic conditions ro ro ro ro ro ro ro ro ro




(positive electrode) - answers02 + 4H+ +4e- -> 2H20 ro ro ro ro ro ro ro ro




Electrode reactions in hydrogen-oxygen fuel cell in acidic conditions ro ro ro ro ro ro ro ro ro




(negative electrode) - answersH2 -> 2H+ + 2e- ro ro ro ro ro ro ro




Brosted- lowry Acid - answersproton donor ro ro ro ro ro




Brosted- lowry base - answersproton acceptor ro ro ro ro ro




weak acids - answerspartially dissociate in aqueous solution
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what is an acidic buffer made of? - answersweak acid and its salt
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what is an basic buffer made of? - answersweak base and its salt
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spontaneous reactions - answerswhen enthalpy is negative and entropy is positive ( spontaneous at all temperatures)
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when enthalpy is positive and entropy is negative (not spontaneous at any temp)
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Stereoisomerism - answersMolecules with the same structural and molecular formula but have a different spatial ro ro ro ro ro ro ro ro ro ro ro ro ro ro




arrangement
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Enthalpy change - answersHeat energy change at constant pressure ro ro ro ro ro ro ro ro




Oxidation of primary alcohols - answersAldehyde ro ro ro ro ro ro




(Alcohol in excess + product distilled off immediately) Carboxylic acid (oxidising agent in excess + Under reflux )
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Oxidation of secondary alcohols - answersKetones ro ro ro ro ro ro




No further oxidation ro ro




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