Putting a couple teaspoons of sugar into a cup of tea seems like a simple enough task. Many people do it every day and never give it a second thought. It seems to be absorbed while giving your tea a sweet flavour. However, what happens to the sugar depends on the solubility of the sugar.
Solubility is a term used to describe a component's ability to dissolve a substance. There are two parts to understanding solubility. First, one must understand that the first component in solubility has to do with the solvent. The solvent is usually a liquid. The liquid can either be a mixture or a pure substance. The second part to this equation is the solute. The solute can be a solid, a gas or a liquid.
Solvent and solute
When sugar is immersed in a cup of tea, the tea acts as the solvent. The sugar, in turn, acts as the solute. When the sugar is put into the tea, the solvent chemically breaks down the solute's molecules, thus seeming to absorb it and producing a sweetened tea. The solubility of the sugar depends on whether it's been hardened by exposure to air. Hardened sugar will take longer to dissolve than sugar that hasn't been exposed to air.