Answer :
Final answer:
To calculate the sodium content in a 250 mL isoosmotic sodium bicarbonate solution, we multiply the volume of the solution (0.25 L) by the osmolarity of plasma (300 mosm/L), which equates to 75 mEq of sodium.
Explanation:
The question asks for the amount of sodium in milliequivalents (mEq) contained in 250 mL of a sodium bicarbonate solution that is isoosmotic with plasma, which has an osmolarity of 300 mosm/L. To find this, we utilize the fact that osmolarity is a measure of solute concentration expressed in osmoles of solute per liter of solution. Moreover, since sodium bicarbonate (NaHCO3) dissociates into sodium (Na+) and bicarbonate (HCO3-) ions, each NaHCO3 contributes one Na+. Given the osmolarity of plasma (300 mosm/L), we can assume an equal osmolarity for the sodium bicarbonate solution to be isoosmotic. Thus, 250 mL of the solution will have 0.25 L × 300 mosm/L = 75 mosm of Na+, which also equals 75 mEq, as 1 mEq of Na+ is equal to 1 mmol of Na+.
