Combining Enthalpy Changes
Thermodynamics Worksheet
Break down the following equations into steps
1. ½Cl2(g) → Cl–(g) + e– (Note: Formation of ion)
Enthalpy of Atomisation
First Electron Affinity
½Cl2(g)
→
Cl(g)
Cl(g) + e–
→
Cl–(g)
2. Na(s) → Na+(g)
Enthalpy of Atomisation
First Ionisation Energy
Na(s)
→
Na(g)
Na(g)
→
Na+(g) + e–
3. Mg(g) → Mg2+(g) + 2e–
First Ionisation Energy
Second Ionisation Energy
Mg(g)
→
Mg+(g) + e–
Mg+(g)
→
Mg2+(g) + e–
4. Na(s) + ½Cl2 → NaCl(aq)
Enthalpy of Formation (Sodium Chloride)
Enthalpy of Solution (Sodium Chloride)
Na(s) + ½Cl2(g)
→
NaCl(s)
NaCl(s)
→
NaCl(aq)
5. Ca2+(g) + O2-(g) → CaO(aq)
Enthalpy of Hydration (Calcium Ions)
Enthalpy of Hydration (Oxide Ions)
Enthalpy of Solution
Ca2+(g)
→
Ca2+(aq)
O2-(g)
→
O2-(aq)
OR
Lattice Enthalpy of Formation
Ca2+(g) + O2-(g)
→
CaO(s)
CaO(s)
→
CaO(aq)
6. K(g) + Br(g) → K+(g) + Br–(g)
First Ionisation Enthalpy (Potassium)
First Electron Affinity (Bromine)
K(g)
→
K+(g) + e–
Br(g) + e–
→
Br–(g)