Why does sugar dissolve in water?

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The question of why sugar dissolves in water is not difficult to explain if you first look at what sugar and water actually are chemically. Also, you need to mention the type of solution.

What are sugar and water

First, look at the molecules of both substances to see why sugar dissolves in water.

  • Water has the formula H.2O. In this context, the arrangement of the H and O atoms in the water is very important. If these were arranged in a line, i.e. H-O-H, water would probably not be a good solvent. The hydrogen atoms are in one angle of 104.5 °, the molecules are dipoles.
  • Now look at what sugar is. Common household sugar is always in crystalline form. No matter how finely the sugar is ground (e.g. B. Powdered sugar) or how big the crystals are (e.g. B. Candy), sugar is always a crystal.
  • The molecular formula of sucrose is C.12H22O11. Regardless of the specific arrangement in the molecule, this indicates that sugar is a molecule made up of carbon atoms and water. More detailed studies show that the sugar molecules have a large number of OH groups. These groups have a negative charge, so the corresponding other group from the molecules must be positively charged because sugar as a whole has no charge.
  • The special arrangement of these OH groups means that the sugar molecules combine to form a crystal lattice. Even if the individual sugar molecule is quite large, you cannot see it with the naked eye. But you see the larger number of molecules that combine to form a crystal.
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Why sugar is in H2O dissolves

  • The sugar sits in the crystal lattice due to its respective dipoles, that is, a negative point of the sugar molecule binds itself electrically to a positive one of another sugar molecule (see Sketch). This is what you see as sugar, the crystals, not the molecules.
  • Put these crystals in water, then the freely moving dipoles of the water push themselves between these crystals. So you push the crystals apart, the sugar molecules move freely in the water.

In contrast to a solution of table salt in water, in which the molecule also breaks down and sodium and chlorine ions are formed, the sugar molecules themselves do not change when sugar is in water solves. Only the crystal is broken. So it is a purely mechanical physical distribution of the molecules, which you absolutely have to mention.

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