Chapter 14, Problem 74E

Nicotinamide is a water-soluble vitamin important in metabolism. A deficiency in the vitamin result in the debilitating condition known as pellagra. Nicotinamide is 59.0% C, 5.0% H, 22.9%N, 13.1%O, by mass. Assition of 30.0 mL nitrobenzene, ${\text{C}}_{\text{6}}{\text{H}}_{\text{8}}{\text{O}}_{\text{2}}$ $\left(d=1.204g/\text{mL}\right)$ , lowers the freezing point from 5.7 to $-14°\text{C}$ . What is the molecular formula of this compound?