Potassium chloride readily dissolves in water. With the use of a labelled diagram, describe the changes in bonding and entropy that occurs during this process. (4 marks)
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- Potassium chloride has a high tendency to dissociate into \(\ce{K^+}\) and \(\ce{Cl^{-}}\) ions when mixed with water (i.e. it is highly soluble).
- Water is a dipolar molecule because each atom has a partial charge, as shown in the diagram.
- The oxygen dipole in water has a partial negative charge and is attracted to the potassium ion. The hydrogen dipoles have a partial negative charge and are attracted to the chloride ion.
- This attraction breaks the ionic bonds and forms ion-dipole bonds.
- The entropy of the system is increased as the ionic bonds of the \(\ce{KCl}\) are broken and the \(\ce{K^{+}}\) and \(\ce{Cl^{-}}\) ions disperse throughout the solution.
Show Worked Solution
- Potassium chloride has a high tendency to dissociate into \(\ce{K^+}\) and \(\ce{Cl^{-}}\) ions when mixed with water (i.e. it is highly soluble).
- Water is a dipolar molecule because each atom has a partial charge, as shown in the diagram.
- The oxygen dipole in water has a partial negative charge and is attracted to the potassium ion. The hydrogen dipoles have a partial negative charge and are attracted to the chloride ion.
- This attraction breaks the ionic bonds and forms ion-dipole bonds.
- The entropy of the system is increased as the ionic bonds of the \(\ce{KCl}\) are broken and the \(\ce{K^{+}}\) and \(\ce{Cl^{-}}\) ions disperse throughout the solution.