A salt solution, also called a saline solution, is simply a mixture of salt and water. Salt is the solute (the dissolving substance), and water is the solvent (the substance that dissolves another to create a solution). To make a salt solution by weight percent (w/v), you apply the formula w/v = (mass of solute ÷ volume of solution) × 100. The density of water is 1 gram per milliliter (g/ml) which means 1 milliliter of water weighs 1 gram.
Things You'll Need
- Graduated cylinder/volumetric flask
Work out how much salt solution you need. For this example, say you need 200 ml of salt solution.
Work out 5 percent of 200, i.e., 0.05 × 200 = 10. To make a 10 percent salt solution, work out 10 percent of 200 and so on. You can also work this out by re-arranging the formula, but multiplying the final volume by the decimal form of the percentage is simpler.
Weigh 10 grams of salt. You can use any type of salt, including table salt.
Pour the salt into a graduated cylinder or volumetric flask containing about 180 ml of water. Swirl the flask gently until all the salt dissolves.
Add enough water to bring the final volume up to 200 ml. Don't simply measure 200 ml of water and add 10 g of salt. Adding salt changes the final volume of the solution and affects the final percentage.
- This formula produces about 3.5 ounces of 5-percent salt solution. It is, however, directly scalable. That is, if you require about a pint or quart of solution then multiply all masses and volumes by 5 or 10, respectively.
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Claire is a writer and editor with 18 years' experience. She writes about science and health for a range of digital publications, including Reader's Digest, HealthCentral, Vice and Zocdoc.