lattice enthalpy
- Created by: olivia johnson
- Created on: 01-05-13 10:16
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- lattice enthalpy
- definition: energy change when one mole of an ionic compound is formed from its gaseous ions at 25 degrees and 1 atm
- exothermic-always has negative value
- standard enthalpy change of atomisation: enthalpy change when one mole of gaseous atoms are formed from the element in its standard state
- 1st electron affinity: enthalpy change when one electron is added to each atom in one mole of gaseous atoms to form gaseous uni NEGATIVE ions
- size and charge of ions affects LE
- LE becomes less exothermic (more positive) as the SIZE of the ions increase
- radius of ion increases so attraction between ions decreases
- LE becomes more exothermic (more negative) as the charge on the ion increases
- this means that ions will have a greater charge density so stronger ionic bonds
- LE becomes less exothermic (more positive) as the SIZE of the ions increase
- enthalpy change of solution: energy change when 1 mole of a ionic solid is totally dissolved in water
- enthalpy change of hydration: energy change when one mole of gaseous ions totally dissolve in water
- always exothermic (requires energy)
- always larger (more exothermic) for ions that have small ionic radii and larger charges.
- this increases chrge density of the ions and attraction between ions and water molecules is also increased
- Hle= Hhyd- Hsol
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