How many grams of NaCl are needed to prepare 5 L of a 0.85% isotonic saline solution?

To prepare an isotonic saline solution, it is important to understand that a 0.85% (w/v) saline solution means there are 0.85 grams of sodium chloride (NaCl) dissolved in every 100 milliliters of solution.

To determine how many grams of NaCl are needed for 5 liters (which is equivalent to 5000 milliliters), the calculation can be set up as follows:

1. Determine the number of grams of NaCl needed for 100 milliliters:

• For a 0.85% solution, you have 0.85 grams in 100 mL.

2. Compute the total grams needed for 5000 mL:

• The relationship is linear, so you can scale it up.

• Use the proportion:

[

\text{Grams of NaCl} = \text{(0.85 grams / 100 mL)} \times 5000 mL

]

This simplifies to:

[

\text{Grams of NaCl} = 0.85 \times 50 = 42.5 \text{ grams}

]

Thus, to prepare a