Regular table salt has an average grain size of 100 microns, or 0. 1 mm. [1] X Research source Note that other types of household salt, such as kosher or pickling salt, will have widely divergent average grain sizes. Regular granulated sugar has an average grain size of 500 microns (0. 5 mm), or five times larger than table salt. [2] X Research source Again, other sugars, like powdered or brown sugar, will have very different average sizes.
Since salt is 100 microns across and sugar is 500, a 250 micron (0. 25 mm) sieve would make a good in-between choice. [3] X Research source
Because this method relies on the difference in average grain sizes, it is never going to be entirely successful, There will be some smaller sugar grains that slip through and some larger salt grains that stay put, not to mention those that might stick together — at least until the point when you’re tired of sifting. Despite its limitations, however, sieving is a legitimate scientific means of separation. [5] X Research source Just don’t expect to use the separated sugar in your coffee, unless you like a salty kick!
Separating salt and sand involves adding warm water to the combination in order to dissolve the salt, straining out the sand by pouring the water mix through a fine sieve, then carefully boiling the water to leave the salt behind. It does not involve flammable liquids or potentially dangerous fumes. [6] X Research source The safety issue is likely the main reason why it is hard to find lesson plans or legitimate scientific advice about how to separate salt and sugar. If you insist upon doing so, however, take every precaution. Do not try it at home unless you are well-versed in chemistry and have observed all safety measures. First and foremost, always have a working fire extinguisher nearby.
If at all possible, consider using only a small amount of salt and sugar or doing your separation in batches if you have a large amount. Ethanol is flammable and using too much will increase your fire risk.
Granulated sugar is a substance containing carbon molecules that is soluble in alcohol and other organic solvents (such as acetone, for example). Table salt, however, is far less soluble in alcohol than it is in water because the former’s lesser polarity provides less attraction to salt’s sodium and chlorine ions. [8] X Research source [9] X Research source
Remember that table salt has an average grain size of 100 microns, so you will need a strainer with smaller mesh openings than that. [10] X Research source You may want to instead use a coffee filter placed inside the sieve.
A steam bath is similar to a double boiler used in cooking. [11] X Research source
Only after placing the alcohol solution in the top bowl, heat up the water to a low boil on medium heat. The steam bath is designed to gently heat the solution because of the alcohol’s volatility. Other methods can cause a spark and light the alcohol. Do not let the alcohol solution come in contact with the heating element or any open flame. Stay away from the steam forming at the top of your open container of sugar and alcohol while it distills.
Exercise caution until and even beyond the conclusion of the experiment. Any remaining alcohol residue could be ignited by the still-hot heating element.
