It is desired to prepare one litre of decimolar aqueous aluminium sulphate. Find the amount of solute to be weighed. Calculate the number of gram ions of sulphate in the solution.

Explanation

Gram formula weight of aluminium sulphate, `Al_(2)(SO_4)_(3)` is `342 g mol^(-1)`
One litre of one molar solution requires to dissolve `342g ` of `Al_(2)(SO_4)_(3)`
One mole of `Al_2(SO_4)_(3)` = Three gram ions of `SO_(4)^(2-)` (sulphate)
Number of gram ions of sulphate `= 3 xx 0.1 = 0.3`