A hydrate whose solid contains five molecules of water of crystallization per molecule, or per unit cell(noun)
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Use "pentahydrate" in a sentence
"THey say that it is treated with Borax and boric acid, which is according to wikipedia “Large amounts of borax pentahydrate are used for manufacturing insulating fibreglass and cellulose insulation as a fire retardant and anti-fungal compound.” although the MSDS also says one should wear a mask while installing so perhaps the babies lying on the insulation is not such a good idea. wl Says:"