What will the osmolarity of a 25 mM KCl solution be?Multiple choice question.50 mOsm1 Osm12.5 mOsm25 mOsm

Break Down the Problem

1. Identify the dissociation of KCl when dissolved in water.
2. Calculate the contribution to osmolarity from the dissolved ions.

Relevant Concepts

• KCl dissociates into two ions in solution: K$^+$ and Cl$^-$.
• Osmolarity is defined as the total concentration of solute particles in a solution. For ionic compounds, this is equal to the sum of the concentrations of the individual ions.

Analysis and Detail

1. Dissociation of KCl:
   KCl → K$^+$ + Cl$^-$
   This indicates that each formula unit of KCl yields two particles in solution.

2. Calculation of Osmolarity:
   Given the concentration of KCl is 25 mM (which is the same as 0.025 M):
   The osmolarity (Osm) is calculated as:
   $\text{Osmolarity} = \text{Concentration} \times \text{Number of particles}$
   Here, the number of particles is 2 (K$^+$ and Cl$^-$).

   So,
   $\text{Osmolarity} = 0.025 \, \text{M} \times 2 = 0.050 \, \text{Osm} = 50 \, \text{mOsm}$

Verify and Summarize

The dissociation of KCl into two ions has been accurately taken into account, and the calculations are correct. The osmolarity of the 25 mM KCl solution is confirmed.

Final Answer

50 mOsm