Salinity Help!

[ngabby80]

I need help in making a solution of water that has 0.5% salinity. I don't have any graduated cylinders , but I do have measuring cups. Does anyone know how much salt I need to add?

[willrosenthal]

"If you measure out exactly one cup of the 100% master salt solution and add exactly one cup of distilled water to it, you now have a 50% solution of salt water. By adding the same amount of plain water to the 100% master salt solution, you have cut its concentration in half (1/2 = 0.5 = 50%). If you take 1/4 cup of the master salt solution and add 3/4 cup of distilled water to it, you now have a 25% salt water solution (1/4 =0.25 = 25%) The mixing ratios could be expressed as A) percentages, B) parts, or C) ratios (E.g. 1:1, 1:2. etc), but the ratios tend to confuse people, so I'll stick with the percentage and parts method of explaining the dilutions.

If you take 1/8 cup of the master solution and add 7/8 cup of distilled water, you now have a 12.5% salt water solution (1/8 = 0.125 = 12.5 %). Switching over to the milliliter system (ml): if you take 10 ml of the master solution and add 90 ml of distilled water, you now have a 10% salt water solution. If you take 5 ml of the master solution and add 95 ml of distilled water, you now have a 5% solution. I could have said the same thing using ounces (oz.) instead of milliliters: if you take 5oz. of the master solution and add 95ozs. of distilled water, you still have a 5% salt water solution. Using a base of "100", it's relatively easy to measure out the exact percentage of salt water concentration that you want."
http://educate-yourself.org/dc/saltwatersolutions.shtml