Final answer:
When the mixture of potassium nitrate and water is warmed, the solubility of potassium nitrate increases, allowing more crystals to dissolve.
Step-by-step explanation:
When potassium nitrate (KNO3) crystals are added to cold water, some of the crystals may not dissolve at room temperature. However, if the contents of the mixture in a beaker are warmed, the solubility of potassium nitrate increases, and more of the crystals will dissolve.
This is because solubility is temperature-dependent. As temperature increases, the kinetic energy of the water molecules increases. This increased kinetic energy allows the water molecules to move more vigorously and break apart the ionic bonds holding the potassium and nitrate ions in the crystal lattice of potassium nitrate.
When the ionic bonds are broken, the potassium and nitrate ions separate and become surrounded by water molecules, forming hydrated ions. These hydrated ions remain in solution and do not re-crystallize. Therefore, warming the mixture increases the solubility of potassium nitrate and allows more crystals to dissolve.