How does stirring make sugar in water dissolve quicker?

Answer 1

Stirring enhances not only sugar dissolving in tea, but the same phenomenon applies every time a solid is dissolved in a solvent (the liquid phase).

Let's look at what happens if a sugar crystal dissolves in tea:

The sugar molecules leave the crystal and enter into the tea surrounding it. After some time you have a high concentration of sugar molecules just next to the remaining crystal.

Now we have to consider another effect: The tea (or any solvent for that matter) can only accommodate a certain amount of molecules being dissolved in it (in our case the sugar). When the limit is reached there is no space (simply put) for any more sugar molecules left.

Stirring removes the sugar molecules next to the remaining sugar crystal by distributing them in the rest of the tea, so that now there is new space for additional sugar molecules to exit from the crystal into the tea.

Without stirring, the sugar molecules also get distributed through your whole cup of tea, by a process called diffusion, but this is much slower than simply stirring the tea.

Answer 2

If you stir it you're making particles collide and dissepear

Answer 3

Stirring the sugar breaks down the particles, And dissolves the sugar faster.