(a) Define polyatomic ions. Write an example.
(b) Calculate the formula unit mass of `CaCO_(3)` (Atomic mass of C=12u, Ca=40u, O=16u)
(c) Calculate the molecular mass of the following
(i) `HNO_(3)` (ii)`CH_(3)COOH`
Atomic mass of H=14N, N=14u, O=16u, C=12u

Explanation

(a) Polytomic ions are the ions represting a group of atoms which carry either postivite or negative charge.
For example, `(SO_(4))^(2-)` ions .
(b) Formula units mass of `CaCO_(3) = ( 1xx "Atomic mass of Ca") + ( 1 xx "Atomic mass of C") + ( 3 xx "Atomic mass of O")`
` = 4 (1xx 40 u) + (1xx 12 u) + (3 xx 16u) = 100u`
(c) Molecular mass of `CH_(3)COOH = (2xx "Atomic mass of C")+( 4 xx "Atomic mass of H") +(2 xx "Atomic mass of O")`
`= (2 xx 12 u) + (4 xx 1 u) + (2 xx 16 u) = 60u`