Question

The compound adrenaline contains 56.79% C, 6.56% H, 28.37% O, and 8.28% N by mass. Whatis the empirical formula of adrenaline?

Short answer

The empirical formula of adrenaline is $C_8{H}_{11}{O}_{3}N$.

Step-by-step solution

Adrenaline compound’s composition

The composition of adrenaline compound by mass can be calculated as,

$$\begin{gathered} C:56.79Percent \\ H:6.56Percent \\ O:28.73Percent \\ N:8.28Percent \end{gathered}$$

Mole calculation of each element

The moles of each element in 100 g can be calculated as,

$\begin{array}{rcl}C& =& 56.79g\times \frac{1molC}{12.01g}\\ & =& 4.729molC\\ H& =& 6.56g\times \frac{1molC}{1.008g}\\ & =& 6.508molH\\ O& =& 28.73g\times \frac{1molC}{16.00g}\\ & =& 1.796molO\\ N& =& 8.28g\times \frac{1molC}{14.01g}\\ & =& 0.591molN\end{array}$

Division of moles

On dividing each of the moles,

$\begin{array}{rcl}\frac{4.729}{0.591}& =& 8C\\ \frac{6.508}{0.591}& =& 11H\\ \frac{1.796}{0.591}& =& 3.40O\\ \frac{0.591}{0.591}& =& 1N\end{array}$

The empirical formula of adrenaline compound can be found as $C_8{H}_{11}{O}_{3}N$.