為甚麼落鹽可以令蛋浮起但糖不能？

Compare two solutions, one salt, one sugar (sucrose) with the same density.

Put 35 grams of salt in 1 liter of water and you get about a liter plus about another milliliter of solution. The result is a salt water solution of about 1.026 grams/milliliter, the same density as ocean water.

To get this density with sucrose, you need to add about double the mass of sucrose or, 70 grams of sucrose in a liter of water yields a liter plus a couple of milliliters. The result is a sugar water solution of about 1.026 grams/milliliter.

To get the same result, you had to put in more sucrose, but the sucrose molceules are a lot larger and have a greater mass, so one needs to consider how many molecules of each type were put it. There are 108 grams/mole of sucrose and 58.45 grams/mole of NaCl so there were fewer sucrose molecules. But, since sodium chloride ionizes and sucrose does not, you got two ions for each NaCl unit, so the number of dissolved species in each case is not all that different.

If you put equal masses of sugar and salt in a solution, then salt water is more dense. If you put equal numbers of dissolved species, it is not so different.

為甚麼落鹽可以使蛋浮起,但是落糖不能浮起呢?
答案是加鹽入水中的份量多少會影響到,其溶液的密度間接影響到與蛋的比重.若果該鹽溶液的比重大過蛋的比重時,則可以將蛋浮起. 至於糖和鹽一樣是可以溶解入水中,所以祇有變成鹽和糖的溶液而已.