Question

A 2.0% saline solution is:

• A. Hypotonic
• B. Hypertonic
• C. Isotonic
• D. Iso-osmotic

Answer 1

The Correct Option is B

To determine why a 2.0% saline solution is considered hypertonic, we need to understand the concepts behind tonicity and the concentration of saline solutions relative to the human body's cells and fluids.

Definition of Relevant Terms:

• Saline Solution: A solution of sodium chloride (NaCl) in water.
• Tonicity: It is the ability of a solution to cause a cell to gain or lose water, specifically the osmotic pressure gradient across a semipermeable membrane.
• Hypotonic: A solution with a lower concentration of solutes compared to the cells, causing water to enter the cells.
• Hypertonic: A solution with a higher concentration of solutes compared to the cells, causing water to exit the cells.
• Isotonic: A solution with the same solute concentration as the cells, leading to no net movement of water.

Human body's normal isotonic saline concentration: Approximately 0.9% NaCl (often referred to as "normal saline").

Analysis:

• A 2.0% saline solution contains approximately 20 grams of NaCl per liter of water, which is significantly higher than the isotonic concentration of 0.9% NaCl.
• This increased concentration means that the 2.0% saline solution has a higher osmolarity than the fluid inside human cells.

Conclusion: Given that the 2.0% saline solution has a higher concentration of solutes than the isotonic environment of cells, it will draw water out of cells. This results in the cells shrinking due to the osmotic pressure difference. Therefore, the solution is hypertonic.

Thus, the correct answer is Hypertonic.