Revisit Final Exam

What is the definition of enthalpy change of hydration (ΔH_hyd​)?

• The enthalpy change when one mole of gaseous ions is dissolved in sufficient water to give an infinitely dilute solution

• The enthalpy change when one mole of ionic solid dissolves in water to form aqueous ions.

• The energy required to break one mole of a specific bond in a molecule in the gas phase.

• The enthalpy change one mole of an ionic solid dissolves in water to give an infinitely dilute solution

What is the definition of entropy (S)?

• Number of possible arrangements of particles in a system under standard conditions.

• Number of possible arrangements of the particles and their energy in a

  given system

• Number of possible arrangements of particles in a system, regardless of their energy.

• Energy required to increase the disorder or randomness in a system.

What is meant by a buffer solution?

• A buffer solution is a solution that resists changes in pH upon the addition of small amounts of acid or base.
• A solution that neutralizes any acid or base added to it.

• A buffer solution is a solution that changes pH dramatically when acid or base is added.
• A solution that is formed from a weak acid and its conjugate base only.

What is a conjugate acid-base pair?

• A conjugate acid-base pair is a pair of species that differ by oxidation number.

• A conjugate acid-base pair is a pair of species that are both acids.
• A conjugate acid-base pair is a pair of species that are identical in charge.
• A conjugate acid-base pair is a pair of species that differ by one proton.

What is the definition of lattice energy (ΔH_latt​)?

• The energy required to break an ionic solid into gaseous ions.

• The energy released when one mole of an ionic compound is formed from its gaseous ions.

• The enthalpy change when an ionic solid dissolves in water.

• The energy released during a chemical reaction involving covalent bonds.

What is the sign of the entropy change (ΔS^∘) for the reaction
2H₂O₂ → 2H₂O + O₂?

• Negative
• Zero
• Undefined
• Positive

Answer explanation

Positive, due to the increase in gas molecules.

The solubility of Al(OH)₃ is 2.47 × 10⁻⁹ mol dm⁻³. Ksp = [Al³⁺][OH^–]³
What is the calculated K_sp value?

• 1.01×10⁻³³ mol⁴ dm⁻¹²

• 3.72 × 10⁻³⁵ mol⁴ dm^-12

• 1.21 10⁻²⁵ mol³ dm^-9

• 1.01×10⁻²⁵ mol³ dm⁻⁹

The color change when titrating Fe²⁺ with MnO₄⁻ is

• Purple to colorless

• Pale green to brown

• Pale green to purple

• Colorless to purple

What is the geometry of the [Ni(en)₃]²⁺ complex?

• Tetrahedral
• Square planar
• Trigonal bipyramidal
• Octahedral

Which reaction mechanism is involved in the reaction between benzene and CH₃CH_2​Cl in the presence of AlCl₃?

• Nucleophilic substitution
• Electrophilic addition
• Electrophilic substitution

• Friedel-Crafts alkylation