By Jack Brubaker. Updated Aug 30, 2022.

A weight percent is a fundamental unit in analytical chemistry, expressing the concentration of a solute relative to the total mass of the solution. It is calculated as (mass of solute ÷ total mass of solution) × 100 %. For a 5 % NaCl solution, five grams of sodium chloride are present for every 100 grams of the entire mixture.

Step 1 – Weigh the Salt

Accurately weigh 199 g (≈7 oz) of high‑purity table salt using a balance capable of 1 g precision. If a balance is unavailable, you can approximate the mass by using 10.5 level tablespoons, since one tablespoon of salt weighs roughly 1 oz.

Step 2 – Dissolve in Distilled Water

Pour one gallon (≈3.785 L) of distilled water into a clean, dry container. Add the weighed salt directly to the water, cap the container, and invert it repeatedly until no undissolved crystals remain. The resulting solution will be a homogeneous 5 % NaCl mixture.

Step 3 – Label the Solution

Remove the original label and use a permanent marker to write “5 % NaCl” on the bottle, ensuring the concentration is clearly documented.

Materials Required

• Analytical balance (1 g or 0.1 oz accuracy)
• Table salt (NaCl)
• 1 gallon of distilled water
• Permanent marker

TL;DR – Quick Calculation

A gallon of water weighs 8.34 lb (≈133 oz). Adding 7 oz of salt gives a total mass of 140 oz. The weight percent is therefore (7 ÷ 140) × 100 % = 5 % NaCl.