Module 5

• Acid-base pair: A pair of two species that transform into each other by gain or loss of a proton
• Bronsted-Lowry acid: A species that donates a proton
• Bronsted-Lowry base: A species that accepts a proton
• Buffer solution: A system that minimises pH changes on addition of small amounts of an acid or a base
• Complex ion: A transition metal ion bonded to ligands by coordinate bonds (dative covalent bonds)
• Conjugate acid: A species that releases a proton to form a conjugate base
• Conjugate base: A species that accepts a proton to form a conjugate base
• Coordination number: The total number of coordinate bonds formed between a central metal ion and ligands
• Entropy: A measure of the dispersal of energy in a system which is greater, the more disordered a system
• First ionisation energy: The energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions
• Half-life: The time taken for concentration of a reactant to decrease by half
• Lattice enthalpy: Formation of 1 mol of ionic lattice from gaseous ions
• Ligand: A molecule or ion that forms a coordinate bond to a transition metal ion by donating a pair of electrons
• Mole fraction: Mole fraction of A = no. of moles of A / total no. of moles in gas mixture
• Order: The power to which the concentration of a reactant is raised in the rate equation
• Overall order: The sum of the individual orders of reactants in the rate equation: m + n
• Oxidising agent: A reagent that oxidises (takes electrons from) another species
• Partial pressure: The pressure a gas in a mixture would exert if it alone occupied the whole container
• pH: The expression, pH = - log[H+(aq)]
• Rate constant, k: The constant that links the rate of reaction with the concentrations of the reactants raised to the powers of their orders in the rate equation
• Rate of reaction: The change in concentration of a reactant or a product in a given time
• Rate determining step: The slowest step in the reaction mechanism of a multi-step reaction
• Reducing agent: A reagent that reduces (adds electron to) another species
• Enthalpy change of formation, ΔfH: Formation of 1 mol of a compound from its elements
• Enthalpy change of hydration, ΔhydH: Dissolving of 1 mol of gaseous ions in water
• Enthalpy change of solution, ΔsolH: Dissolving of 1 mol of solute
• Transition element: A d-block element which forms an ion with an incomplete d-sub-shell
• Reasons for entropy change: change in moles of gas, increase in mobility of ions, change in states, less/more disorder
• Free energy change equation: ∆G=∆H-(T∆S/1000)
• Entropy change equation: ∆Sr = (Sum of ∆S products) - (Sum of ∆S reactants)
• What makes a buffer: weak acid and strong alkali
• Half cell if metal used in equation: metal electrode
• Half cell if metal not used in equation: Platinum(Pt) electrode
• Half cell if ions in acid solution: Platinum(Pt) electrode, all products in solution
• Half cell for gas system: platinum (Pt) electrode, 101kPa, 1atm
• Gas pressure standard conditions: 100kPa/101kPa/1atm
• Temperature standard conditions: 298K/25C
• Standard ion concentration: 1.0moldm^-3
• Eqm shifts to the left for more negative cell potential, shifts to right for more positive cell potential
• Ecell = Erhs - Elhs