1. Understand Percentage Concentration

A 5% NaCl solution means that 5 grams of NaCl are dissolved in every 100 mL of solution.

2. Calculate the Grams Needed

* Convert mL to L: 4000 mL = 4 L

* Set up a proportion:

5 g NaCl / 100 mL = x g NaCl / 4000 mL

* Solve for x:

x = (5 g NaCl * 4000 mL) / 100 mL

x = 200 g NaCl

Therefore, you need 200 grams of NaCl to prepare 4000 mL of a 5% solution.