Question

How would you determine the solubility of potassium nitrate?

Answer 1

Hint: To solve this we must know that potassium nitrate is an ionic compound. The chemical formula for potassium nitrate is ${\text{KN}}{{\text{O}}_{\text{3}}}$. Potassium nitrate is an ionic salt of potassium cations i.e. ${{\text{K}}^ + }$ ions and nitrate anions i.e. ${\text{NO}}_3^ - $ anion.

Complete step by step answer:
- We know that potassium nitrate is an ionic compound. The chemical formula for potassium nitrate is ${\text{KN}}{{\text{O}}_{\text{3}}}$.
- A compound composed of oppositely charged cations and anions in proportions that give electrical neutrality is called an ionic compound.
- Thus, potassium nitrate is an ionic salt of potassium cations i.e. ${{\text{K}}^ + }$ ions and nitrate anions i.e. ${\text{NO}}_3^ - $ anion. When potassium nitrate is dissolved in water it dissociates into potassium cations i.e. ${{\text{K}}^ + }$ ions and nitrate anions i.e. ${\text{NO}}_3^ - $ anion. This is an endothermic process.
- To determine the solubility of potassium nitrate we must know the solubility rules for ionic compounds.
- Potassium nitrate is an alkali metal nitrate. Thus, we must know the rule for solubility of nitrates.
- The rule for the solubility of nitrates is as follows: The salts that contain the nitrate anion i.e. ${\text{NO}}_3^ - $ anion are generally soluble in water.
Thus, potassium nitrate i.e. ${\text{KN}}{{\text{O}}_{\text{3}}}$ is soluble in water.

Note: When potassium nitrate is dissolved in water it dissociates into potassium cations i.e. ${{\text{K}}^ + }$ ions and nitrate anions i.e. ${\text{NO}}_3^ - $ anion. This is an endothermic process. In this process, heat is absorbed by the system from its surrounding. Thus, the vessel feels colder when potassium nitrate is dissolved in water.