Question 1: A giant ionic lattice is a three-dimensional structure composed of a regular arrangement of positive and negative ions held together by strong electrostatic forces. These lattices form the basis of many ionic compounds with characteristic properties such as high melting points and electrical conductivity when molten or dissolved.

Answer: A three-dimensional structure of ions held together by electrostatic forces, forming ionic compounds.

Question 1: Define a giant ionic lattice.

Answer: A repeating three-dimensional arrangement of ions held together by electrostatic forces.

Question 2: Explain why ionic compounds have high melting points.

Answer: Because a large amount of energy is required to break the strong electrostatic forces between the ions in the lattice.

Question 3: Describe the movement of ions in a molten ionic lattice compared to a solid ionic lattice.

Answer: In a molten lattice, ions are free to move and conduct electricity, whereas in a solid lattice, ions are fixed in place and do not conduct electricity.

Question 1: Calculate the number of moles of sodium ions in 50 grams of sodium chloride (NaCl). (Molar mass of NaCl = 58.44 g/mol)

Answer: 0.855 mol

Question 1: Describe a safe method to observe the melting point of an ionic compound in a laboratory setting.

Answer: Use a controlled heating apparatus like a melting point apparatus, wear safety goggles and gloves, and ensure proper ventilation. Avoid direct contact with hot equipment.

Question 2: Identify the variables in an experiment to measure the electrical conductivity of an aqueous ionic solution.

Answer: Independent variable: Concentration of the solution; Dependent variable: Electrical conductivity; Control variables: Temperature, type of ionic compound, electrode material.

Question 1: A sample of potassium chloride (KCl) dissolves in water and conducts electricity. Explain the reason for this conductivity based on the structure of KCl.

Answer: The potassium and chloride ions dissociate in water, forming free ions that carry electrical charge, allowing conduction.

Question 1: Explain why ionic compounds tend to be brittle and how this relates to the structure of the ionic lattice. (6 marks)

Answer: Ionic compounds are brittle because when a force is applied, like charges are forced close, causing repulsion and shattering of the lattice. The regular repeating arrangement of ions means that applying stress can shift ions into positions where like charges are adjacent, leading to fracture.

Question 1: Describe how knowledge of ionic lattices is important in the development of salt-based batteries.

Answer: Understanding the structure and properties of ionic lattices helps in designing batteries where ionic movement within the lattice allows for efficient charge transfer and energy storage.