Complex sentence: With hard water, soap solutions form a white precipitate (soap scum) instead of producing lather, because the 2 + ions destroy the surfactant properties of the soap by forming a solid precipitate (the soap scum).
Split into simpler sentences: With hard water, soap solutions form a white precipitate (soap scum) instead of producing lather. This effect arises because the 2 + ions destroy the surfactant properties of the soap by forming a solid precipitate (the soap scum).