thermodynamics Flashcards
electron affinity (2)
Enthalpy change/heat energy change when one mole of gaseous atoms
Form (one mole of) gaseous negative ions (with a single charge)
why electronegativity of F greater than Cl (2)
Fluorine (atom) is smaller than chlorine/shielding is less/ outer electrons closer to nucleus
(Bond pair of) electrons attracted more strongly to the NUCLEUS/PROTONS
why hydration enthalpy of fluoride ion more neg than cl ion (2)
Fluoride (ions) smaller (than chloride) / have larger charge density
So (negative charge) attracts (δ+ hydrogen on) water more strongly
how to calc ∆H(solution)
∆H(solution) = LE + Σ(hydration enthalpies)
why … is always spontaneous process (2)
Entropy change is positive/entropy increases and enthalpy change negative/exothermic
So ∆G is (always) negative
suggest condition under which element C (diamond) would have entropy value of 0
absolute 0/ 0K/-273C
REMEMEBR AT 0K entropy is 0
enthalpy of atomisation (2)
Enthalpy change for the formation of 1 mol of gaseous atoms
From the element (in its standard state)
lattice dissociation enthalpy (2)
Enthalpy change to separate 1 mol of an ionic lattice/solid/compound
Into (its component) gaseous ions
perfect ionic model (2)
ions r perfect spheres
ONLY electrostatic attraction/ no covalent interaction
enthalpy of lattice formation
enthalpy change when 1 mol of solid ionic compound/ ionic lattice is formed from its gaseous ions
enthalpy of hydration
(enthalpy change when) 1 mol of gaseous (fluoride) ions (is converted) into aqueous ions / an aqueous solution
explain interactions bw h20 molecules + f- when f- become hydrated
water is polar / H on water is / is electron deficient / is unshielded
(F– ions) attract water / on H / hydrogen
why … more spontaneous even tho change is endthermic
molecules become more disordered
so entropy change is pos
so TΔS>ΔH
ΔG<0
why is it that if compound shows covalent character it has larger values than theoretical values
bc forces/bonds holding lattice tg are stronger
