Final answer:
0.45% NaCl solution, also known as half normal saline (1/2 NS), is a hypotonic solution. It contains 4.5 grams of NaCl per liter and is used to provide water and electrolytes in a medical setting without increasing blood volume too quickly.
Step-by-step explanation:
The solution known as 0.45% sodium chloride or 0.45% NaCl is commonly referred to as half normal saline (1/2 NS). This concentration of NaCl is considered a hypotonic solution when compared to the human body's plasma. In medical settings, hypotonic solutions like this are used to provide patients with electrolytes and water without causing a rapid increase in blood volume.
In the context of preparing solutions, if this concentration were to be prepared in a laboratory, it would involve dissolving 4.5 grams of NaCl in enough water to make a total volume of one liter. To achieve accurate concentrations, a volumetric flask would typically be used. This ensures that the final volume accounts for the space taken up by the dissolved sodium and chloride ions in the solution.
For reference, normal saline, which has a mass/volume percent of 0.9% NaCl, contains 9.0 grams of NaCl per liter. This is twice the concentration of half normal saline and is an isotonic solution, matching the body's own osmolarity.