The Chemical Level Of Organization - Chapter questions - Problem 3CT

A chemical change involves a reaction in which products are different chemically from reactants. The dissolution of sucrose in water changes the physical form of the solute but not its chemical properties. This can be demonstrated by evaporating all the water from a sugar solution. It can be shown by chemical tests that what remains in the beaker (vessel), after complete evaporation of the water solvent, is not a mixture of fructose and glucose, but a substance that has all the properties of sucrose. So the solution process did not break sucrose bonds, for the substance left after evaporation has all the chemical qualities of sucrose. The chemical explanation is as follows: In the sucrose molecules O-H bonds are slightly polar. The oxygen atom is slightly negative and the hydrogen atom is slightly positive. The water molecule(H-O-H) is also slightly polar--the oxygen atoms being slightly negative and the hydrogen atoms being slightly positive. The positive hydrogen atoms of water attracts the negative oxygen atoms of sucrose and the negative oxygen atoms of water are attracted to the positive hydrogen of the sucrose molecules. The sucrose molecules are held together in crystals by inter-molecular forces which include hydrogen bonds and dipole dipole forces. But the attraction to water molecules is stronger that the inter-molecular attraction and the water molecule attraction lifts the sucrose molecules out of their crystal lattice. The water molecules surround or solvate the sucrose molecules and that is what solution or dissolution is.