Technically salt can be any ionic compound formed by reacting an acid and a base, but most of the time the word is used to refer to table salt, which is sodium chloride or NaCl. So, you know salt contains sodium, but the two chemicals aren't the same thing.
What Is Sodium?Sodium is a chemical element. It is very reactive, so it isn't found free in nature. In fact, it undergoes spontaneous combustion in water, so while sodium is essential for human nutrition, you wouldn't want to eat pure sodium! When you ingest salt, the sodium and the chlorine ions in sodium chloride separate from each other, making the sodium available for your body to use.
Sodium in the BodySodium is used to transmit nerve impulses and is found in every cell of your body. The balance between sodium and other ions regulates the pressure of cells and is related to your blood pressure, too.
How Much Sodium Is in Salt?Because sodium levels are so critical to so many chemical reactions in your body, the amount of sodium you eat or drink has important implications for your health. If you are trying to regulate or limit your intake of sodium, you need to realize the quantity of salt you eat is related to the amount of sodium, but is not the same. This is because salt contains both sodium and chlorine, so when salt dissociates into its ions, the mass is divided (not equally) between sodium and chlorine ions.
The reason salt isn't just half sodium and half chlorine is because a sodium ion and a chlorine ion don't weight the same amount.
Sample Salt and Sodium CalculationFor example, here is how to calculate the amount of sodium in 3 grams (g) or salt. You will notice 3 grams of salt does not contain 3 grams of sodium, nor is half the mass of salt from sodium, so 3 grams of salt does not contain 1.5 grams of sodium:
Na: 22.99 grams/mole
Cl: 35.45 grams/mole
1 moles of NaCl = 23 + 35.5 g = 58.5 grams per mole
sodium is 23/58.5 x 100% = 39.3% of salt is sodium
Then the amount of sodium in 3 grams of salt = 39.3% x 3 = 1.179 g or about 1200 mg
An easy way to calculate the amount of sodium in salt is to realize 39.3% of the amount of salt comes from sodium. Just multiply 0.393 times the mass of the salt and you will have the mass of sodium.