Question

if the molar mass of butanoic acid is 88.1g/mol, what is its molecular formula?

Answer 1

The structural formula of butanoic acid is CH3-CH2-CH2-COOH( molecular formula is C4H8O2) 
atomic weights of C,H,O are 12,1.008,16 respectively, 
So the molecular weight of butanoic acid is (12 x4) +(8x1.008) + (2 x16) = 88