Draw the Bond-Haber cycle for the formation of one mole of calcium sulphide (CaS). The relevant data from which the cycle is constructed are: Standard Enthalpy of formation of CaS =-482KJ/mol Sublimation energy of Calcium = +176 KJ/mol Sum of first two ionization energy for calcium = +1690 KJ/mol Enthalpy of formation of gaseous sulphur atoms = +240 KJ/mol Electron affinity for sulphur for two electrons = +449KJ/mol Calculate the lattice energy for CaS What is lattice energy Why is the total electron affinity for sulphur positive?
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.
Question 1
Draw the Bond-Haber cycle for the formation of one mole of calcium sulphide (CaS).
The relevant data from which the cycle is constructed are:
Standard Enthalpy of formation of CaS =-482KJ/mol
Sublimation energy of Calcium = +176 KJ/mol
Sum of first two ionization energy for calcium = +1690 KJ/mol
Enthalpy of formation of gaseous sulphur atoms = +240 KJ/mol
- Calculate the lattice energy for CaS
- What is lattice energy
- Why is the total electron affinity for sulphur positive?
- Cucl2 is a stable compound, whereas neither CaCl nor CaC3 are known as unstable compounds. Account for this observation.
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