Question

8 Define office energy for lonic crystalline compounds. Analyze each of the two situations below and ordain the corresponding lon pairs following their crescent lattice energy Explain your rationale for each of the situations Situation A (ordain the lon pairs below the figure in crescent order of lattice energy Explain). 0.76 A 2. A 102 220 Your answer: Situation B (ordain the lon pairs below the figure in crescent order of lattice energy. Explain). F 1.33 Mg? 0.72 * 0? 1.40 SN 0.88 À 1.46 A Li 0.76 À Your answer:

Answer 1

Lattice energy of an ionic crystal It is defined as the amount of energy released when one mole of gaseous cations and one mule of gaseous anion brought together from infinite separation to form om one mole of ionic crystal is called Latice energy M"(3) + xy - MX (3) +U Imola Imole . I mole Here, U = Lattice energy Theoretically lattice energy can be caleulated by Boxn- Lande equation which is given as U = MNA Z+2-02 471€. To l Here, M= pedel Modelung Constant which is summation of all geometrical interactions between ions. NA = = Augadaro's number A constant 2+ = charge on cation 2- = Y = charge on lomil_yoeli cation and anion equilibrium anion distance between n = gt is having larger value larger ions relatively higher cleehon density. .

S ie, ua Z+Z- te to Carater La NaI KI U zz = 21 remains constant (1) ro Increases because si all have common I but chora ionic radie of cation increases in the order - Let < Nat <kt (111) n increases because electron density increases Thus, (1) Lattice energy decreases R 2+2 ztz- ztz- I Lef=1 Mgo =4 SEN =9 (i) ztz increases di) no invreases (Lif & Mgo chave almost same to) (1) n increases (but the effect of his very less) Thus, (iv) effect of ztze dominate and u invieases.