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This question is about magnesium and magnesium chloride - AQA - GCSE Chemistry - Question 5 - 2016 - Paper 2
Question 5
This question is about magnesium and magnesium chloride. (a) Magnesium chloride contains magnesium ions (Mg²⁺) and chloride ions (Cl⁻). Describe, in terms of electr... show full transcript
Worked Solution & Example Answer:This question is about magnesium and magnesium chloride - AQA - GCSE Chemistry - Question 5 - 2016 - Paper 2
Step 1
Magnesium chloride contains magnesium ions (Mg²⁺) and chloride ions (Cl⁻). Describe, in terms of electrons, what happens when a magnesium atom reacts with chlorine atoms to produce magnesium chloride.
Answer
When a magnesium atom reacts with chlorine atoms, it undergoes an ionic reaction. In this process, the magnesium atom loses two electrons, resulting in the formation of a magnesium ion (Mg²⁺). At the same time, two chlorine atoms each gain one electron, leading to the formation of two chloride ions (Cl⁻). This transfer of electrons results in the creation of magnesium chloride (MgCl₂), which consists of one magnesium ion and two chloride ions, fulfilling the noble gas configuration.
Step 2
Explain why magnesium chloride must be molten or dissolved in water to be electrolysed.
Answer
Magnesium chloride must be either molten or dissolved in water because, in this state, the ions are free to move. When solid, the ions are held in a rigid lattice structure and cannot move, preventing the conduction of electricity. In the molten or aqueous state, ions can move towards the electrodes, allowing the electrolysis process to occur.
Step 3
Explain how magnesium is produced at the negative electrode in Experiment 1.
Answer
In Experiment 1, magnesium is produced at the negative electrode due to the electrolysis of molten magnesium chloride. Magnesium ions (Mg²⁺) from the electrolyte are attracted to the negative electrode. At this electrode, each magnesium ion gains two electrons, resulting in the reduction of magnesium ions to elemental magnesium metal. The half-equation for this reaction is:
ightarrow ext{Mg}$$Step 4
Step 5
Suggest why magnesium is not produced at the negative electrode in Experiment 2.
Answer
Magnesium is not produced at the negative electrode in Experiment 2 because the conditions favor the production of hydrogen gas instead. This occurs because hydrogen ions (from water) are more easily reduced than magnesium ions. Since hydrogen is more reactive, it is produced at the negative electrode.
Step 6
Step 7
Magnesium is a metal. Explain why metals can be bent and shaped.
Answer
Metals can be bent and shaped due to their unique structure. The layers of atoms or ions in the metal are held together by metallic bonds, which allow the layers to slide over each other without breaking the overall structure. This gives metals their malleability and ductility, enabling them to be formed into various shapes.