Question

Molarity of 98% (by mass) of H2SO4 having density 1.75gm/cc is [consider H2SO4 is solute]
(A) 14.5 M
(B) 17.5 M
(C) 16.5 M
(D) 15.5 M

Answer 1

Molar mass of H2SO4 = 98g/mol = Mm
D =density = 1.84g/cc
W/w = 98%
V = 1dm3 = 1L = 1000ml = 1000cc
Mass of solution = V x D
M = 1000 x 1.84 = 1840g per 1000cc
Using w/w, 98% of 1840g = H2SO4
= (98/100) x 1840 = 1803.2g = m
Nos of moles = m/Mm = 1803.2/98 = 18.4moles per 1000cc
Thus, molarity = 18.4M (18.4mol/dm3)