(i) Butyric acid contains only `C, H` and `O.A4.24 mg` sample of butyric acid is completely burned. It gives `8.45 mg` of carbon dioxide `(CO_(2))` and `3.46 mg` of water. What is the mass percentage of each element in butyric acid?
(ii) If the elemental composition of butyric acid is found to be `54.2% C, 9.2% H` and `36.6%O`, determine the empirical formula.
(iii) The molecular mass of butyric acid was determined of experiment to be `88`. What is the moleculare formula ?

Answer

B, C, D

Explanation

(i) Calculation of empirical formula

Empirical formula `=C_(2)H_(4)O`
(ii) Calculation of molecular formula
Empirical formula mass `=2 xx 12 + 4 xx 1 + 1 xx 16 = 44`
Molecular mass = 88
`n=("Molecular mass")/("Empirical formula mass") = 88/44 =2`
`therefore` Molecular formula `=2(C_(2)H_(4)O) = C_(4)H_(8)O_(3)`.