25 cm3 of 0.02 M KOH neutralized 0.03 g of a monobasic organic acid having…

25 cm³ of 0.02 M KOH neutralized 0.03 g of a monobasic organic acid having the general formula C_nH_{2n + 1} COOH. The molecular formula of the acid is?
(C = 12, H = 1, O = 16)

Correct Answer: Option C

Explanation

Conc. of KOH = 39 x 0.02 = 0.78 g/dm³
25cm³ require 0.03 g of C_nH_{2n + 1} COOH 1000CM³ → x x = (1000) / (25) x 0.03 = 1.2g
C_nH_{2n + 1}COOH + KOH → C_nH_{2n + 1} COOK + H₂O
from (M_AV_A) / (M_B x V_B) = (1) / (1) (M_A x 1.2) / (0.02 x 0.78) = (1) / (1)
M_A = 0.013
Con. = Molarity x Molecular Mass
Molecular Mass = (0.78) / (0.013) x 60
C_nH_{2n + 1} COOH = 60
12n + 1 (2n + 1) + 12 + 32 + 1 = 6
14n = 60 – 46; n = (14) / (14) = 1
∴ CH₃COOH