Complex sentence: It is closely related to the more commonly encountered potassium permanganate, but it is generally less desirable, because it is more expensive, absorbs water from the atmosphere, and has a low melting point.
Split into simpler sentences: It is closely related to the more commonly encountered potassium permanganate, but it is generally less desirable, because it is more expensive to produce. This salt absorbs water from the atmosphere and has a low melting point.