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This question is about sodium chloride and iodine - AQA - GCSE Chemistry - Question 6 - 2015 - Paper 2
Question 6
This question is about sodium chloride and iodine. (a) Describe the structure and bonding in sodium chloride. (b) When sodium chloride solution is electrolysed, on... show full transcript
Worked Solution & Example Answer:This question is about sodium chloride and iodine - AQA - GCSE Chemistry - Question 6 - 2015 - Paper 2
Step 1
Describe the structure and bonding in sodium chloride.
Answer
Sodium chloride (NaCl) has a distinctive ionic structure characterized by a lattice or giant structure. In this structure, sodium ions (Na⁺) and chloride ions (Cl⁻) are arranged in a three-dimensional grid, attracting each other through strong electrostatic forces of attraction. These forces arise from the transfer of one electron from sodium to chlorine, resulting in positively charged sodium ions and negatively charged chloride ions.
Step 2
Step 3
Give one ethical reason why a compound of iodine should not be added to sodium chloride used in food.
Answer
One ethical reason against adding a compound of iodine to sodium chloride is that individuals should have the right to choose what they consume, and mandatory iodization may violate personal dietary preferences.
Step 4
Step 5
Explain why iodine has a low melting point.
Answer
Iodine has a low melting point because it exists as simple molecules with relatively weak intermolecular forces, specifically van der Waals forces. These forces are easily overcome with lower energy compared to stronger covalent bonds, allowing iodine to transition from solid to liquid at lower temperatures.
Step 6
Explain, in terms of particles, why liquid iodine does not conduct electricity.
Answer
Liquid iodine does not conduct electricity because it consists of neutral molecules with no free or mobile electrons or ions available to carry charge. The covalent bonds within iodine molecules do not allow for the movement of charged particles necessary for electrical conductivity.