Calculate the formula unit mass of `Al_(2)(SO_(4))_(3)`.

Explanation

Atomic mass of aluminium is 27 u, of sulphur is 32 u and of oxygen is 16 u.
`[Al^(3+), SO_(4)^(2-)]`
Formula unit mass of `Al_(2)(SO_(4))_(3)`
`= 2 xx 27) + 3(1 xx 32) + (4 xx 16)`
= 54 + 3(32 + 64)
= 54 + 3(96)
= 54 + 288 = 342
`:.` the formula unit mass of `Al_(2)(SO_(4))_(3)` is 342 u.