Prelim Round
Problem 1. (10 marks) According to the given information and condition, write the chemical equation of the following reaction.
1-1 To get nanomaterials with good performance, use the reaction between cluster compound K₁₂Si₁₇ and NH₄Br to make nanosilicon.
1-2 Selenosulfate is oxidized by a certain concentration of H₂O₂ under acidic conditions, and the main product is similar to that of thiosulfate oxidized by I₂.
1-3 Elemental Tellurium (Te) and AsF₅ react in the solvent SO₂ at a stoichiometric ratio of 6:3, the main product is Yichrome diamagnetic solid, and its anion has an octahedral structure
1-4 Make perbromate by reacting XeF₂ with bromate solution.
1-5 Mixed solution of sodium molybdate (Na₂Mo04) and thioacetamide (CH₃CSNH₂) in strongly acidic medium under hydrothermal conditions react to prepare the two-dimensional material MoS₂. (Reminder: When BaCl₂ is added to the acidic concentrated solution after separation of MoS₂, and a white precipitate appears,)
Solution
1-1 K₁₂Si₁₇ + 12NH₄Br → 17Si + 12KBr + 12NH₃ + 6H₂ (2 marks)
1-2 2SeSO₃²⁻ +H₂O₂+2H⁺ → Se₂S₂O₆²⁻ + 2H₂O (2 marks)
1-3 6Te + 3AsF₅ → Te₆(AsF₆)₂ + AsF₃ (2 marks)
1-4 XeF₂ + BrO₃ + H₂O → Xe + BrO₄ + 2HF (2 marks)
1-5 4MoO₄²⁻ + 9CH₃CSNH₂ + 15H⁺ + 6H₂O → 4MoS₂ + SO4²⁻ + 9CH₃COOH + 9NH₄⁺ (2 marks)