QJEEM23Ch8ff9: JEE Main 2023 Chemistry - Class 11 JEEM23Ch8ff9 Solution: Given below are two statements: Statement I : Aqueous solution…
Given below are two statements:
Statement I : Aqueous solution of K Cr O is preferred as a primary standard in volumetric analysis over Na Cr O aqueous solution.
Statement II : K Cr O has a higher solubility in water than Na Cr O .
In the light of the above statements, choose the correct answer from the options given below:
Multiple Choice Options
- A Statement I is true but Statement II is false
- B Both Statement I and Statement II are false
- C Statement I is false but Statement II is true
- D Both Statement I and Statement II are true
Step-by-Step Verified Solution
Statement I: Potassium dichromate (K Cr O ) is indeed commonly used as a primary standard in volumetric (titrimetric) analysis. It is a powerful oxidizing agent and has a high equivalent weight. Furthermore, it is readily available, it can be obtained in a high state of purity, it is not hygroscopic, and its solutions are stable. However, the reason it is preferred over sodium dichromate (Na Cr O ) is not due to its solubility, but rather its stability and molar mass.
Statement II: Typically, the solubility of salts increases with the size of the cation. Sodium ions (Na ) are smaller than potassium ions (K ), so sodium salts tend to be more soluble in water than corresponding potassium salts. Thus, we would expect sodium dichromate (Na Cr O ) to be more soluble in water than potassium dichromate (K Cr O ).
Therefore, the correct answer is Option A: Statement I is true but Statement II is false.