Question

a compound with the molar mass 135 g/mol has an empirical formula of chn. what is the molecular formula of the compound?
chn
c₆h₆n₆
c₃h₃n₃
c₅h₅n₅

Explanation:

Step1: Calculate the empirical formula mass

The atomic masses are \(C = 12\space g/mol\), \(H= 1\space g/mol\), \(N = 14\space g/mol\).
The empirical formula \(CHN\) has a mass \(M_{empirical}=12 + 1+14=27\space g/mol\)

Step2: Find the ratio \(n\)

We know that \(n=\frac{M_{molecular}}{M_{empirical}}\)
Given \(M_{molecular} = 135\space g/mol\) and \(M_{empirical}=27\space g/mol\)
\(n=\frac{135}{27}=5\)

Step3: Determine the molecular formula

Multiply each sub - script in the empirical formula \(CHN\) by \(n = 5\)
The molecular formula is \(C_{5}H_{5}N_{5}\)

Answer:

\(C_{5}H_{5}N_{5}\)