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.
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Answer
Sodium chloride has a giant ionic structure, often referred to as a lattice structure. In this structure, sodium ions (Na⁺) and chloride ions (Cl⁻) are arranged in a three-dimensional pattern. The ions are held together by strong electrostatic forces of attraction between the oppositely charged ions. Each sodium ion donates one electron to a chlorine atom, resulting in the formation of ions that create this stable arrangement.
Step 2
Name the two other products from the electrolysis of sodium chloride solution.
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The two other products from the electrolysis of sodium chloride solution are hydrogen gas (H₂) and sodium hydroxide (NaOH).
Step 3
Give one ethical reason why a compound of iodine should not be added to sodium chloride used in food.
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One ethical reason could be that individuals should have the right to choose what they put in their bodies, and mandatory addition of iodine may infringe on personal choice.
Step 4
Complete Figure 4 to show the bonding in iodine.
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In Figure 4, iodine atoms should be represented with one bond pair of electrons between them, showing two unbonded electrons on each atom, indicating that iodine forms diatomic molecules (I₂).
Step 5
Explain why iodine has a low melting point.
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Iodine has a low melting point because it consists of simple molecular structures where the forces between the molecules are weak intermolecular forces (van der Waals forces). These forces require only a small amount of energy to overcome, allowing iodine to become a solid at low temperatures.
Step 6
Explain, in terms of particles, why liquid iodine does not conduct electricity.
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Liquid iodine does not conduct electricity because it consists of neutral molecules that do not carry any charge. Since there are no free ions or charged particles available to move and conduct electricity, liquid iodine remains an insulator.
