5.34g of salt of formula M
2SO
4 (where M is a metal) were dissolved in water. The sulphate ion was precipitated by adding excess barium chloride solution when 4.66g of barium sulphate (BaSO
4) were obtained.
a) How many moles of sulphate ion were precipitated as barium sulphate?
b) How many moles of M
2SO
4 were in solution?
a) Barium and sulphate exist in a one-to-one ratio in the compound , so the number of moles of barium sulphate equals the number of moles of sulphate. Beside, how to get the exact value of moles?