system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: why is cocoa powder easy to solve in little water/milk but makes lumps if dissolved in more liquid?
gpt
Flour and starches (like corn starch) is like this too and other hydrophobic powders. Basically when these powders encounter liquid, they will react and some dissolve, but they form little balls where the inside can stay dry and not mix with the water, just the outside of the ball has to react and the structure can keep the water from permeating past the outside layer. With just a small amount, it’s easy to crush the balls that form and force it to all dissolve. You can smash the ball with a spoon for example. Now instead put that in a glass, or a big pot full of liquid, where there is far more liquid than powder and it’s much much harder to break up that ball. Hitting it just makes it float away as the liquid itself provides resistance to your moving spoon, so it’s not enough force to break apart the ball. Even if you try to trap it against the wall or bottom, because of all of the liquid, it is much easier for the ball to squirt away. A general rule of thumb with a lot of powders being mixed with liquid is to mix it with a much smaller amount of liquid first to actually get it all dissolved and then dilute with whatever the actual amount of liquid you want to use.