5.2 Energy Flashcards

1
Q

Lattice enthalpies give an indication of the strength of ionic bonding
How would the lattice enthalpies of magnesium chloride and calcium chloride differ?
Explain your answer
(3 marks)

A

-lattice enthalpy of MgCl2 is more exothermic than CaCl2
-because magnesium ion (Mg2+ ) is smaller than calcium ions (Ca2+) or Mg2+ has a greater charge density
-therefore the attraction between Mg2+ and Cl- is greater (than between Ca2+ and Cl- )

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2
Q

Define the term lattice enthalpy
(2 marks)

A

-the enthalpy change that accompanies the FORMATION of ONE MOLE of an ionic compound from its GASEOUS IONS under standard conditions

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3
Q

The first ionisation energy of sodium is more endothermic than that of potassium
Explain why
(2 marks)

A

-sodium has a smaller atomic radius OR it has fewer shells

-therefore nuclear attraction increases

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4
Q

The lattice enthalpy of sodium oxide is more endothermic than that of potassium oxide
Explain why
(2 marks)

A

-Na+ ions are smaller
-Na+ has stronger attraction to O2-

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