The boiling point of a substance is typically associated with the temperature at which it changes from a liquid to a gas. However, potassium nitrate KNO3 does not have a specific boiling point at a pressure of 760 mm Hg because it decomposes before reaching its boiling point. When heated, potassium nitrate undergoes thermal decomposition, breaking down into potassium nitrite KNO2 and oxygen gas O2 at around 400C 752F . This decomposition occurs before KNO3 has a chance to transition from a solid to a liquid and then to a gas. Therefore, it is not possible to provide a boiling point for potassium nitrate at a pressure of 760 mm Hg.