Eli5: I mixed two different brands of epsom salts and found they later went slushy, what would cause this?

Question

I kind of thought epsom salt brands would be fine to mix so I put the new one I got into the old bag that was almost finished.

It really just looks like someone just put water in the bag with the salts but I know I didn’t so that’s not the case. I guess lesson learned for next time but I’m also just curious to understand why.

Thanks in advance!

In: Chemistry

Answer 1

I’m thinking that one of the salts wasn’t actually magnesium sulfate, but some chloride salt, which reacted with the magnesium sulfate to form magnesium chloride, which is deliquescent, meaning it sucks moisture from the air to such a degree that it becomes liquid.