Final answer:
An IV bag of isotonic 0.9% NaCl (normal saline) is typically used to correct abnormal serum osmolality, as it helps maintain equilibrium and physiological homeostasis without causing net water movement between blood and tissues.
Step-by-step explanation:
To correct a patient's abnormal serum osmolality, the nurse may be ordered to hang an IV bag of a substance that will help return the patient to normal serum osmolality by adjusting fluid balance. An IV bag of 0.9% NaCl, often referred to as normal saline (NS), is likely to be used for this purpose because it is isotonic with respect to body fluids.
When administered, it will maintain equilibrium, since there would be no net movement of water across the blood and tissue compartments, thus helping maintain physiological homeostasis.