Lattice energies and electron affinities are very difficult to measure experimentally. Fairly reliable theoretical values for lattice energies can be calculated from simple models. The Born-Haber cycle can then be used to estimate electron affinities. Use the data below to calculate the electron affinity of iodine (in kJ mol1), where a negative EA value indicates a favourable anion formation. Name of enthalpy change Value in kJ/mol Formation enthalpy of Cal2(s) -533.46 Lattice energy of Cal2 -2074 Sublimation enthalpy of Ca 177.7 First ionization energy of Ca 589.8 Second ionization energy of Ca 1145.4 Sublimation enthalpy of I2 62.44 Bond energy of l2 151.1
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
Step by step
Solved in 2 steps with 1 images
