Are addresses of Chipmixer known? Don't have idea about this although have used a few times.
All addresses are known, and it's easy to get
all addresses with a balance that could be a ChipMixer chip. But anyone can create chip-sized inputs, so you'll never know for sure.
While checking the
FAQ: this is outdated:
You can bet a chip to either receive twice as big one or receive nothing. Chance to receive big chip is around 47% and is provably fair.
And this too:
Why should I use bet/donate function?