EARTH SCIENCE
GEOCHEMISTRY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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K2O will have the higher lattice energy due to the larger atomic mass of K compared to Na
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Na2O will have the higher lattice energy due to the decreased shielding and higher charge density of Na ions compared to K ions
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K2O will have the higher lattice energy due to the increased shielding and lower charge density of K ions compared to Na ions
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Both lattice energies would be the same due to the Na and K both being in the same period and having the same charge
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Detailed explanation-1: -Sodium and potassium ions both have the same charge (+1) but the potassium ion is larger so the electrostatic forces of attraction are weaker in potassium oxide. Hence less energy is required to separate the ions making the enthalpy of lattice dissociation less endothermic.
Detailed explanation-2: -The relation of interatomic space and lattice energy is inverse. Here, interionic spacing in magnesium oxide will be smaller than sodium oxide. The listed factors and their impact conclude that magnesium oxide (MgO) would possess higher lattice energy.
Detailed explanation-3: -The lattice energy of CaO(s) is-3460 kJ mol−1; the lattice energy of K2O is-2240 kJ mol−1. This difference is because K+>Ca2+ (size), K+<Ca2+ (charge).
Detailed explanation-4: -The lattice energy of an ionic compound is inversely proportional to the distance between the ions. The farther the distance between the ions in a lattice, the weaker the electrostatic forces holding them together, and the lower the lattice energy.