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Question

Question: How would you determine the solubility of potassium nitrate?...

How would you determine the solubility of potassium nitrate?

Explanation

Solution

To solve this we must know that potassium nitrate is an ionic compound. The chemical formula for potassium nitrate is KNO3{\text{KN}}{{\text{O}}_{\text{3}}}. Potassium nitrate is an ionic salt of potassium cations i.e. K+{{\text{K}}^ + } ions and nitrate anions i.e. NO3{\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 KNO3{\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. K+{{\text{K}}^ + } ions and nitrate anions i.e. NO3{\text{NO}}_3^ - anion. When potassium nitrate is dissolved in water it dissociates into potassium cations i.e. K+{{\text{K}}^ + } ions and nitrate anions i.e. NO3{\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. NO3{\text{NO}}_3^ - anion are generally soluble in water.
Thus, potassium nitrate i.e. KNO3{\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. K+{{\text{K}}^ + } ions and nitrate anions i.e. NO3{\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.