By adding granulated sugar to tea, it dissolves much faster than regular sugar. What is the reason for this difference?

The solution

When sugar is added to warm water, a saturated layer of sugar solution forms around the surface of the sugar crystal, which prevents further dissolution. Thus, the diffusion of dissolved sugar molecules to other parts of the water environment must take place, which takes time. Granular sugar is all together in one place and with a small area. However, ordinary sugar is dispersed in water and therefore has a much larger surface area, so its dissolution rate depends less on the slow diffusion process.