Chem PPQs got wrong topic 5

The lattice enthalpy of sodium oxide is more exothermic than of potassium oxide explain why (2)

Comparison of size of cations

• for sodium ions ionic radius of sodium is smaller

Comparison of attraction of cation and anion

• ~Na+ has stronger attraction to O2-

Explain what is meant by the term enthalpy change of hydration (2)

• the enthalpy change when

• 1 mole of gaseous ions react OR 1 mole of hydrated / aq ions are formed

• gaseous ions dissolve in water OR gaseous ions form aq / hydrated ions

Predict how the enthalpy changes of hydration of F- and Cl- would differ (2)

• enthalpy of hydration of F- is more negative / exothermic than enthalpy of hydration of Cl- AND F- has a smaller size

• F- OR smaller sizes ion linked to greater attraction TO H2O