Sugar

Add two cups of sugar to one cup of water in a saucepan and stir while heating slightly. All the sugar will dissolve. About how much total sugar will dissolve in one cup of water? What is the physics?

Answer

One can usually dissolve about five cups of sugar in one cup of water! Very simply, sugar molecules can squeeze into the empty spaces among the water molecules, so they are not really occupying more space. The water forms somewhat of an open latticework with water molecules loosely connected, so the “holes” in this water lattice can accommodate a large number of other molecules. The sugar molecules form temporary hydrogen bonds to the water molecules, these bonds breaking and reforming continually. Essentially the rule is “like dissolves like.” Of course, the sugar molecules are quite large, and one cup of sugar molecules contains only about one twenty-fifth the number of water molecules in a cup. So there are many water molecules to every sugar molecule in the solution.