What is the value of n when the empirical formula is c3h5 and the molecular mass is 205.4?

Empirical formula is the simplest ratio of whole numbers of components in a compound.

the empirical formula - C₃H₅

mass of empirical formula - (12 g/mol x 3) + (1 g/mol x 5) = 41 g

we have to find how many empirical units make up the molecular formula

number of empirical units = molecular mass / mass of empirical formula

empirical units = 205.4 g/mol / 41 g = 5.00

molecular formula - n (C₃H₅)

n - number of empirical units

therefore n = 5