system
Given the following post, respond as if you're commenting on Reddit:
human
Why does rice suck the moisture out of things?
gpt
Rice (like a lot of other grains) is hygroscopic, which means it can trap water molecules inside of it thanks to long biopolymers like cellulose. Rice can gain and lose water in a sort of osmotic balance with the atmosphere. It balances out so that the vapor pressure of water inside the rice grain is equal to that of the atmosphere outside. If you put a wet phone in a closed bag with dry rice, the equilibrium eventually shifts from wet phone and dry rice to less wet phone and wetter rice.

Cooked rice is already supersaturated with water, so that's why you only use dry rice to desiccate your phone.