Problem 15 - Chemistry: The Central Science

Question

We have learned in this chapter that many ionic solids dissolve in water as strong electrolytes; that is, as separated ions in solution. Which statement is most correct about this process? (a) Water is a strong acid and therefore is good at dissolving ionic solids. (b) Water is good at solvating ions because the hydrogen and oxygen atoms in water molecules bear partial charges. (c) The hydrogen and oxygen bonds of water are easily broken by ionic solids.

Step-by-Step Solution

Answer

The correct answer is (b). Water is good at solvating ions because the hydrogen and oxygen atoms in water molecules bear partial charges. Water molecules are polar, with partial positive charges near the Hydrogen atoms and partial negative charges near the Oxygen atom. This allows charged ions in ionic solids to interact with the partial charges on water molecules through solvation, thus facilitating the dissolution process.

Step 1: Look at option (a)

Water is a strong acid and therefore is good at dissolving ionic solids. This statement is incorrect. Water is not a strong acid, it's actually amphoteric meaning it can act both as an acid and a base. Moreover, the ability to dissolve ionic solids is not solely determined by the acidity of a substance.

Step 2: Look at option (b)

Water is good at solvating ions because the hydrogen and oxygen atoms in water molecules bear partial charges. This statement is correct. Water molecules are polar, meaning they have a partial positive charge near the Hydrogen atoms and a partial negative charge near the Oxygen atom. When ionic solids dissolve in water, the charged ions of the solid can interact with the partial charges on water molecules. This interaction is known as solvation, and it helps to stabilize the ions in solution, facilitating the dissolution process. So the correct answer is (b).

Step 3: Look at option (c)

The hydrogen and oxygen bonds of water are easily broken by ionic solids. This statement is incorrect. The hydrogen and oxygen atoms in a water molecule are linked through covalent bonds, which are strong and not easily broken by ionic solids. The dissolution process involves interactions between the ions and the partial charges on water molecules, but it does not involve breaking actual H-O bonds within water molecules.