QUESTION 2 [16 marks]

Question

Iron and water are often used in packs to treat athletic injuries. The packs
contain a type of magnesium sulfate and a pouch of water. When the pouch is
broken, the water begins to dissolve the magnesium sulfate.
MgSO4 ( s ) Mg2+
( aq) + SO4
2-
(aq )
7

Answer 1

It seems that you're looking for some information or analysis related to the dissolution of magnesium sulfate (MgSO4) in water, specifically in the context of its use in packs for treating athletic injuries. Let's break this down step by step.

Reaction

The dissolution process can be represented as follows:

\[ \text{MgSO}_4 (s) \rightarrow \text{Mg}^{2+} (aq) + \text{SO}_4^{2-} (aq) \]

Explanation

1. Dissolution Process:

   • When the pouch containing water is broken, water comes into contact with the solid magnesium sulfate.
   • This interaction leads to the dissociation of the magnesium sulfate into its constituent ions: magnesium ions (\(\text{Mg}^{2+}\)) and sulfate ions (\(\text{SO}_4^{2-}\)).

2. Endothermic Reaction:

   • The dissolution of magnesium sulfate in water is typically an endothermic process, meaning it absorbs heat from the surroundings. This is likely what makes the packs feel cold when activated. The energy required to break the ionic bonds in the solid and separate the ions is obtained from the thermal energy of the surroundings.

3. Application in Athletic Injuries:

   • The cold packs are useful for treating athletic injuries because they help reduce swelling and inflammation. By lowering the temperature in the affected area, the packs can alleviate pain and minimize further injury.

Points for Consideration (Potential Marking Criteria)

1. Clear Description of the Reaction (2 marks):

   • The chemical equation for the dissolution of magnesium sulfate was provided correctly.

2. Explanation of the Process (2 marks):

   • An understanding of how magnesium sulfate dissolves and dissociates into ions should be adequately explained.

3. Thermal Properties (3 marks):

   • Mention that the process is endothermic and discuss the implications of this characteristic.

4. Practical Applications (3 marks):

   • Discuss how the cooling effect is utilized in treating injuries and the physiological benefits.

5. Safety and Effectiveness (3 marks):

   • Optionally, mention any safety considerations or the effectiveness of magnesium sulfate compared to other treatment methods for injuries.

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