CHE-11 Revision Week 1

In an exothermic reaction, what is the enthalpy change (ΔH) value?

• Always positive.

• Always negative.

• Can be either positive or negative.

• Close to zero.

What is the definition of ionic bonding?

• • Electrostatic attraction between positive ions and delocalised electrons.

• Electrostatic attraction between oppositely charged ions.

• Electrostatic attraction between the nuclei of two atoms and a shared pair of electrons.

• Transfer of electrons from a non-metal to a metal.

What is the definition of lattice energy (ΔH latt)

• The enthalpy change when 1 mole of an ionic compound is formed from its solid ions.

• The enthalpy change when 1 mole of gaseous atoms is formed from its element.

• The enthalpy change when 1 mole of an ionic compound is formed from its gaseous ions.

• The energy required to break bonds between atoms in an element.

Which of the following factors does not affect the electron affinity of an element?

• Nuclear charge.

• Atomic radius.

• Shielding.

• Temperature.

Why is fluorine's first electron affinity less exothermic than chlorine's?

• Fluorine has a larger atomic radius than chlorine.

• Fluorine has a higher nuclear charge than chlorine.

• Fluorine has a very small atomic radius, which leads to increased repulsion between the incoming electron and the existing electrons.

• Fluorine has more inner electron shells, which increases shielding.

• Which statement correctly describes the Born-Haber cycle?

• It is a specific application of Hess's Law used to calculate standard enthalpy change of formation.

• It is a specific application of Hess's Law used to calculate lattice enthalpy.

• It shows the enthalpy change of a reaction pathway that is independent of the route.

• It calculates enthalpy changes that can be found experimentally using calorimetry.

What is the effect of a higher ionic charge on the lattice energy of an ionic compound?

• The lattice energy becomes less exothermic.

• The lattice energy becomes more endothermic.

• The lattice energy becomes more exothermic.

• Ionic charge has no effect on lattice energy.

Which of the following would lead to a more stable ionic compound?

• Larger ionic radius.

• Weaker electrostatic forces of attraction.

• Less exothermic lattice energy.

• More exothermic lattice energy.

What is the definition of standard enthalpy change of solution (ΔHsol)

• The energy released when ions are combined to form a solid lattice.

• The enthalpy change when 1 mole of specified gaseous ion dissolves in sufficient water.

• The energy absorbed or released when 1 mole of an ionic substance dissolves in sufficient water to form a very dilute solution.

• The enthalpy change when 1 mole of electrons is added to 1 mole of gaseous atoms.

What type of bond is formed between water molecules and ions when an ionic solid dissolves?

• • Covalent bond

• • Ionic bond

• • Hydrogen bond

• Ion-dipole bond