Question

a compound with the molar mass 216 g/mol has an empirical formula of c6h6no. what is the molecular formula of the compound? c18h18n3o3 c12h12n2o2 c3h3n0.5o0.5 c6h6no

Explanation:

Step1: Calculate the empirical formula mass

The empirical formula is \(C_6H_6NO\).
The atomic masses are: \(C = 12\space g/mol\), \(H= 1\space g/mol\), \(N = 14\space g/mol\), \(O = 16\space g/mol\).
The empirical formula mass \(M_{empirical}=(6\times12)+(6\times1)+14 + 16\)
\(M_{empirical}=72 + 6+14 + 16=108\space g/mol\)

Step2: Find the ratio \(n\)

The molar mass \(M = 216\space g/mol\)
\(n=\frac{M}{M_{empirical}}=\frac{216}{108} = 2\)

Step3: Determine the molecular formula

Multiply each sub - script in the empirical formula by \(n = 2\)
For \(C\): \(6\times2 = 12\), for \(H\): \(6\times2=12\), for \(N\): \(1\times2 = 2\), for \(O\): \(1\times2=2\)
The molecular formula is \(C_{12}H_{12}N_2O_2\)

Answer:

\(C_{12}H_{12}N_2O_2\)