ANS:B - Butyl alcohol

The solvent used for the extraction of H3PO4 from CaCl2 solution during the manufacture of ortho-phosphoric acid by the wet process employing hydrochloric acid leaching is butyl alcohol. Explanation:

1. Manufacture of Ortho-phosphoric Acid: In the wet process for manufacturing ortho-phosphoric acid (H3PO4), phosphoric acid is typically produced by leaching phosphate rock with hydrochloric acid. This process generates a solution containing various dissolved salts, including calcium chloride (CaCl2).
2. Extraction of Phosphoric Acid: To extract phosphoric acid (H3PO4) from the solution containing calcium chloride, a solvent extraction step is often employed. Butyl alcohol (also known as n-butanol) is commonly used as the solvent for this purpose.
3. Solvent Selection: Butyl alcohol is preferred for solvent extraction in this process due to its ability to selectively extract phosphoric acid while leaving calcium chloride and other impurities in the aqueous phase. Butyl alcohol forms a separate organic phase where the phosphoric acid is dissolved, allowing for its separation from the aqueous solution.
4. Other Solvents: While other solvents like iso propyl alcohol, toluene, and hexane may have solvent properties, butyl alcohol is specifically chosen for its efficiency and selectivity in extracting phosphoric acid from the solution.
5. Process Efficiency: The use of butyl alcohol as the solvent ensures the efficient recovery of phosphoric acid from the solution, contributing to the overall effectiveness and yield of the ortho-phosphoric acid manufacturing process.