▁solid ▁that ▁dissol ves ▁in ▁water . ▁ ▁It ▁is ▁almost ▁non - h yg ro scop ic ▁and ▁has ▁good ▁sh elf - life . ▁ ▁Production ▁The ▁salt ▁is ▁prepared ▁by ▁the ▁electro ly t ic ▁ox id ation ▁of ▁sod ium ▁hydro gen ▁sul f ate : ▁ 2 ▁Na H SO 4 ▁▁ ▁→ ▁▁▁ ▁Na 2 S 2 O 8 ▁ ▁+ ▁ ▁H 2 ▁Ox id ation ▁is ▁conducted ▁at ▁a ▁plat in um ▁an ode . ▁In ▁this ▁way ▁about ▁ 1 6 5 , 0 0 0 ▁tons ▁were ▁produced ▁in ▁ 2 0 0 5 . ▁▁ ▁The ▁standard ▁re do x ▁potential ▁of ▁sod ium ▁pers ulf ate ▁into ▁hydro gen ▁sul f ate ▁is ▁ 2 . 1 ▁V , ▁which ▁is ▁higher ▁than ▁that ▁of ▁hydro gen ▁per ox ide ▁( 1 . 8   V ) ▁but ▁lower ▁than ▁o zone ▁( 2 . 2   V ). ▁ ▁The ▁sul f ate ▁radical ▁formed ▁in ▁situ ▁has ▁a ▁standard ▁electro de ▁potential ▁of ▁ 2 . 7   V . ▁ ▁However , ▁there ▁are ▁a ▁few ▁draw back s ▁in ▁util izing ▁plat in um ▁an odes ▁to ▁produce ▁the ▁sal ts ; ▁the ▁manufact uring ▁process ▁is ▁in efficient ▁due ▁to ▁o xygen ▁evolution ▁and ▁the ▁product ▁could ▁contain ▁cont amin ants ▁coming ▁from ▁plat in um ▁cor ros ion ▁( main ly ▁due ▁to ▁extremely ▁ox id izing ▁nature ▁of ▁the ▁sul f ate ▁radical ).