Topic 15 Energetics and Thermochemistry

Consider the Born–Haber cycle for the formation of sodium oxide. What is the lattice enthalpy, in kJ mol−1, of sodium oxide?

• 414 + 2(108) + 249 + 2(496) − 141 + 790

• 414 + 2(108) + 249 + 2(496) + 141 + 790

  C. 

• −414 + 2(108) + 249 + 2(496) − 141 + 790

  D. 

• −414 − 2(108) − 249 − 2(496) + 141 − 790

Which substance has the highest lattice enthalpy?

• KCl

• CaCl₂

• KF

• CaF₂

Which represents electron affinity?

• Al²⁺(g) → Al³⁺ (g) + e⁻

• C (g) + e⁻ → C⁻ (g)

• Cl₂ (g) → 2Cl (g)

• S (s) → S⁺ (g) + e⁻

Which combination gives the standard hydration enthalpy of Na⁺ (g)?

• 4 + 359 +790

• 4 + 359 - 790

• -4 - 359 + 790

• 4 - 359 + 790

What is the order of increasing (more exothermic) enthalpy of hydration?

Xn⁺ (g) → Xn⁺ (aq)

• Ca²⁺, Mg²⁺, K⁺, Na⁺


• Na⁺, K⁺, Mg²⁺, Ca²⁺

• K⁺, Na⁺, Ca²⁺, Mg²⁺

• Mg²⁺, Ca²⁺, Na⁺, K⁺

Which equation represents the standard enthalpy of atomization of bromine, Br₂?

• 1/2 Br₂ (l) → Br (g)

• Br₂ (l) → 2Br (g)

• Br₂ (l) → 2Br (l)

• 1/2 Br₂ (l) → Br (l)

Which equation represents lattice enthalpy?

• NaCl (g) → Na⁺ (g) + Cl⁻ (g)

• NaCl (s) → Na⁺ (g) + Cl⁻ (g)

• NaCl (s) → Na⁺ (aq) + Cl⁻ (aq)

• NaCl (s) → Na⁺ (s) + Cl⁻ (s)

Which change is exothermic?

• 1/2 Cl₂ (g) → Cl (g)

• K (g) → K⁺ (g) + e⁻

• KCl (s) → K⁺ (g) + Cl⁻(g)

• Cl (g) + e⁻ → Cl⁻ (g)

What is the enthalpy of solution of MgF₂(s) in kJ mol⁻¹?

Lattice enthalpy of MgF₂(s) = 2926 kJ mol−1

Hydration enthalpy of Mg²⁺(g) = −1963 kJ mol−1

Hydration enthalpy of F⁻(g) = −504 kJ mol−1

•  2926 − 1963 + 2(−504)

• 2926 − 1963 − 504

• −2926 − (−1963) − (−504)

• −2926 − (−1963) − 2(−504)

Which value represents the lattice enthalpy, in kJ mol⁻¹, of strontium chloride, SrCl₂?

• – (–829) + 164 + 243 + 550 + 1064 – (–698)

• –829 + 164 + 243 + 550 + 1064 – 698

• – (–829) + 164 + 243 + 550 + 1064 – 698

• –829 + 164 + 243 + 550 + 1064 – (–698)