Which of the substance has the highest melting point?
Correct answer: D. MgO
- A. CO2
- B. H2O
- C. NaCl
- D. MgO
Explanation
Option D is correct since in Magnesium Oxide, both Magnesium and Oxygen atoms form ions in the lattice. Due to the higher magnitude of the charge on the Magnesium (+2) and Oxygen atoms (-2), the force of attraction between them is very high. This provides them with very high lattice energy and a lot of energy is required to break this lattice; hence the melting point of MgO is high. MgO - 2852o CH2O - 100 oCCO2- 78.46 oCNaCl - 801 oC
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About Lattice Energy
Lattice energy describes the energy released when gaseous ions form one mole of an ionic solid, or the energy required to separate that solid into gaseous ions, depending on the convention used. Its value depends mainly on ionic charge and radius and is calculated through Born-Haber cycles.
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