Question

A 0.9% solution of NaCl is considered isotonic to mammalian cells. what molar concentration is this?

Answer 1

Answer:

58.44 g/mol The Molarity of this concentration is 0.154 molar

Explanation:

the molar mass of NaCl is 58.44 g/mol,

0.9 % is the same thing as 0.9g of NaCl , so this means that 100 ml's of physiological saline contains 0.9 g of NaCl.  One liter of physiological saline must contain 9 g of NaCl.  We can determine the molarity of a physiological saline solution by dividing 9 g by 58 g... since we have 9 g of NaCl in a liter of physiological saline, but we have 58 grams of NaCl in a mole of NaCl.  When we divide 9 g by 58 g, we find that physiological saline contains 0.154 moles of NaCl per liter.  That means that physiological saline (0.9% NaCl) has a molarity of 0.154 molar.  We can either express this as 0.154 M or 154 millimolar (154 mM).