Question

HCl, a strong acid, completely dissociates into two ions in aqueous solution. What is the osmolarity of a 1 mM HCl solution?

Answer 1

An osmole( osmol) is one mole of particles that contribute to the osmotic presssure of a solution.

To calculate the osmolarity you have to multiply the molarity by the number of moles that each solute produces.

HCL dissociates in to H⁺ and CL^- in aqueous solution.

Thus each mole of HCl becomes two osmoles in aqueous solution.

So,

The osmolarity of 1 mM HCl solution = 1 × 2( molarity is given as 1 mM & we understood that its 2 osmolea)

1×2 = 2

SO the osmolarity is 2 osmol/L