Respuesta :

Answer:

To calculate the moles we must first find the molar mass M

M (Na2S2O8) = (23*2) + (32*2) + (16*8)

= 46 + 64 + 168

= 278g/mol

Molar mass = mass/moles

moles =mass / molar mass

= 25.2/278

= 0.0906mol

Hope this helps.