Question

Assuming complete dissociation of all solutes, which of the following solutions would be hyperosmotic to 1 mM NaCl?

1) 1 mM glucose
2) 1.5 mM glucose
3) 1 mM CaCl₂
4) 1 mM sucrose
5) 1 mM KCl

Answer 1

The solution with the highest osmolarity among the given options, making it hyperosmotic to a 1 mM NaCl solution, is 1 mM CaCl₂.

Step-by-step explanation:

To determine which of the given solutions would be hyperosmotic to a 1 mM NaCl solution, we need to compare the number of dissolved particles in each solution. NaCl dissociates into two ions (Na+ and Cl-), so a 1 mM NaCl solution has an osmolarity of 2 osmol. Let's calculate the osmolarities of the given solutions:

1) 1 mM glucose: Since glucose is a non-electrolyte, it does not dissociate into ions. Therefore, the osmolarity of a 1 mM glucose solution is 1 osmol.

2) 1.5 mM glucose: Same as above, the osmolarity would be 1.5 osmol.

3) 1 mM CaCl₂: CaCl₂ dissociates into three ions (1 Ca²+ and 2 Cl-), so the osmolarity would be 3 osmol.

4) 1 mM sucrose: Sucrose is also a non-electrolyte, so the osmolarity would be 1 osmol.

5) 1 mM KCl: KCl dissociates into two ions (K+ and Cl-), so the osmolarity would be 2 osmol.

Comparing the osmolarity values, the solution with the highest osmolarity is 1 mM CaCl₂, making it hyperosmotic to a 1 mM NaCl solution.