SK025 CHAPTER 2:THERMOCHEMISTRY

Which of equation example for the definition:

"The heat release when 1 mol of substance is burned completely in excess oxygen"

• C(s) + 2H₂(g) → CH₄(g)

• HCl(aq) + NaOH(aq) → NaCl (aq) + H₂O(l)

• C₂H₆(l) + 7/2 O₂(g) → 2CO₂(g) + 3H₂O(l)

• Cl^-(g) → Cl^-(aq)

Based on this equation, enthalpy of neutralization must be 1 mol of:

HCl(aq) + KOH(aq) → KCl (aq) + H₂O(l)

• HCl(aq)

• KOH(aq)

• KCl(aq)

• H₂O(l)

Enthalpy combustion:

"The heat release when 1 mol of ____________ is burned completely in excess oxygen"

• compound

• element

• substance

• water

Which of the following equation not the enthalpy of atomisation:

• 1/2Br₂(l) → Br(g)

• Al(l) → Al(g)

• 1/2Cl₂(g) → Cl(g)

• Mg(s) → Mg(g)

Given the enthalpy of formation NO₂(g)

1/2N₂(g) + O₂(g) → NO₂(g) ΔH = +33.0 kJ

Calculate enthalpy of combustion, N₂(g)

• ΔH = +16.5 kJ/mol

• ΔH = +33.0 kJ/mol

• ΔH = -33.18 kJ/mol

• ΔH = +66.0 kJ/mol

Define enthalpy solution:

• the heat absorbed when 1 mole of gaseous atoms is formed from its element

• the heat released when 1 mole of gaseous ions is hydrated in water

• the heat change when 1 mole of a substance is dissolves in excess water to form a very dilute solution

• the heat change when 1 mole of a compound is formed from its elements

Which of the equation correct refer to definition of formation, CH₃OH (g)

• CH₃(g) + OH(g) ----> CH₃OH (g)

• C(s) + H₂(g) + OH₂(g) ----> CH₃OH (g)

• C(s) + 2H₂(g) + 1/2O₂(g) ----> CH₃OH (g)

• C(s) + H₄(g) + O(g) ----> CH₃OH (g)

Which of the equation not the enthalpy of formation:

• Na(s) + 1/2Br₂(l) --------> NaBr(s)

• 2Na(s) + O₂(g) --------> Na₂O(s)

• Al(s) + 3/2Cl₂(g) --------> AlCl₃(s)

• Mg(s) + 1/2Cl₂(g) --------> MgCl₂(s)

Lattice energy :

Energy released when 1 mole of solid ionic compound formed from its gaseous ions.

Which of the equation refer for this definition.

• Na(s) + 1/2 Cl₂(g) --------> NaCl (s)

• Na⁺(g) + Cl^-(g) ---------> NaCl (s)

• NaCl (s) ----------> Na⁺(g) + Cl^-(g)

• Na⁺(aq) + Cl^-(aq) ---------> Na⁺Cl^- (s)

Which of the pair FALSE about their definition of enthalpy:

• Enthalpy of atomisation: 1 mol gaseous atom

• Enthalpy of formation: 1 mol of a substance

• Enthalpy of solution: 1 mol of a substance

• Enthalpy of hydration: 1 mol gaseous ion

• Enthalpy of combustion: 1 mol of substance