Final answer:
Water dissolves sugar because the polar water molecules can interact with and separate the polar sucrose molecules, resulting in the sugar dissolving. Agitation like stirring and increasing temperature can speed up this process but won't change the maximum amount of sugar that can be dissolved, known as solubility.
Step-by-step explanation:
Water dissolves sugar, specifically sucrose, due to the interaction between the polar water molecules and the polar areas on the sugar molecules. Water molecules are polar because they have a partial positive charge on one side and a partial negative charge on the other side. Sucrose is also polar due to its many hydroxyl (-OH) groups. The positive end of water molecules attracts the negative oxygen atoms in the sugar, and the negative end of water molecules attracts the positive ends of the sugar's hydroxyl groups. This interaction breaks the intermolecular forces that hold the sugar molecules together and results in sugar molecules being surrounded by water molecules, a process known as hydration.
Agitation of the solution, such as stirring, helps dissolve sugar faster by moving dissolved sugar away from the surface of remaining sugar, allowing water to contact and dissolve more sugar. Temperature also affects solubility; warming the solution increases the solubility of sugar, allowing more to dissolve. However, these methods do not change the solubility limit of sugar in water, just the rate at which it dissolves.
Once the solution reaches a certain concentration—its solubility limit—no additional sugar will dissolve. The remaining undissolved sugar is due to the balance between solute-solute and solute-solvent attractive forces. In a true solution, such as fully dissolved sugar in water, the sugar does not settle out of the solution and can even pass through a filter as the dissolved particles are very small.