F215 Definitions 4.0 / 5 based on 1 rating ? ChemistryEnthalpyA2/A-levelOCR Created by: ImogenCreated on: 05-06-13 13:33 Lattice Enthalpy The enthalpy change that accompanies the formation of 1 mole of a solid ionic compound from its constituent gaseous ions under standard conditions 1 of 34 Standard Enthalpy Change of Formation The enthalpy change when 1 mole of a compound is formed from its constituent elements in their standard states under standard conditions 2 of 34 Standard Enthalpy Change of Atomisation The enthalpy change when 1 mole of an element forms 1 mole of its gaseous atoms under standard conditions 3 of 34 The First Ionisation Energy The energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous ions with a +1 charge 4 of 34 The First Electron Affinity The energy required to add 1 mole of gaseous electrons to 1 mole of gaseous atoms to form 1 mole of gaseous ions with a 1- charge 5 of 34 Standard Enthalpy Change of Solution The enthalpy change when 1 mole of a compound dissolves completely in water under standard conditions 6 of 34 Standard Enthalpy Change of Hydration The enthalpy change when 1 mole of gaseous ions dissolves in water to form 1 mole of aqueous ions under standard conditions 7 of 34 Entropy A measure of the degree of disorder in a system 8 of 34 Standard Entropy Change of Reaction The entropy change that accompanies a reaction taking place in the molar quantities expressed in a chemical equation under standard conditions. 9 of 34 The Free Energy Change: ΔG = ΔH - TΔS A reaction can only take place spontaneously when ΔG < 0 10 of 34 Standard Conditions 298 K/25C, 1 atm pressure and all solutions at 1 mol dm-3 11 of 34 Rate of Reaction The change in concentration of a reactant or product over time 12 of 34 Initial Rate of Reaction The change in concentration of a reactant or product per unit of time when t=0 13 of 34 The Order of a Reactant The power to which the concentration of a reactant is raised in the rate equation 14 of 34 Rate Constant The constant, k, which links the rate of reaction and the concentration of reactants (which are raised to the power of their orders) 15 of 34 Half-Life The time it takes for the concentration of a reactant to decrease by half 16 of 34 Bronsted-Lowry Acid A proton donor 17 of 34 Bronsted-Lowry Base A proton acceptor 18 of 34 Conjugate Acid-Base Pairs Species that transform into each other on the addition or removal of a proton 19 of 34 Acid Dissociation Constant, Ka The extent to which an acid dissociates in solution 20 of 34 What are the relationships linking pH and [H+]? pH = -log[H+] [H+] = 10^(-pH) 21 of 34 What are the relationships between Ka and pKa? pKa = -log(Ka) Ka= 10^(-pKa) 22 of 34 Strong Acid A strong acid dissociates completely in solution 23 of 34 Weak Acid A weak acid partially dissociates in solution 24 of 34 What Ka/pKa value will a strong acid have? Large Ka value, small pKa value 25 of 34 What Ka/pKa values will a weak acid have? Small Ka value, large pKa value 26 of 34 Buffer Solution A mixture that minimises fluctuations in pH on the addition of small amounts of acid/alkali 27 of 34 Standard Enthalpy Change of Neutralisation The enthalpy change that occurs when 1 mole of water is formed from the neutralisation of an acid by an alkali under standard conditions 28 of 34 Standard Electrode Potential The e.m.f value of a half cell compared to a standard hydrogen half cell under standard conditions 29 of 34 Transition Elements d-block elements that can form at least 1 ion with an incomplete d sub-shell 30 of 34 Ligand A molecule or ion that can donate a pair of electrons to a central transition metal ion to form a coordinate bond 31 of 34 Complex Ion A transition metal ion bonded to one or more ligands by coordinate bonds 32 of 34 Coordination Number The number of coordinate bonds in a complex ion 33 of 34 Stereoisomers Stereoisomers are molecules with the same structural formula but a different arrangement of atoms in space 34 of 34
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