What mass of NaOH is required to precipitate all the Fe2+ ions from 50.0 mL of 0.200 M Fe(NO3)2 solution?

Answer 1

Fe+2 + 2NaOH ==> Fe(OH)2 + 2Na^+
How many moles Fe^+2 do you have? M x L = moles. So look at the equation and determine the moles of NaOH required to react with this many moles iron(II). Then grams NaOH = moles x molar mass.