Question

question ⓘ
the empirical formula is a chemical formula that provides the smallest, whole number ratio of elements in a compound. using the mass of each element or the mass percentage of each element in a compound, the empirical can be determined.
what is the empirical formula for a substance that contains 3.730% hydrogen, 44.44% carbon, and 51.83% nitrogen by mass?
answer
$\boldsymbol{h_2cn}$
$\boldsymbol{hc_{12}n_{14}}$
$\boldsymbol{hcn}$
$\boldsymbol{hcn_2}$
i dont know yet

Explanation:

Step1: Assume 100g sample, get masses

Mass of H = 3.730 g, C = 44.44 g, N = 51.83 g

Step2: Calculate moles of each element

Moles of H: $\frac{3.730\ \text{g}}{1.008\ \text{g/mol}} \approx 3.700\ \text{mol}$
Moles of C: $\frac{44.44\ \text{g}}{12.01\ \text{g/mol}} \approx 3.700\ \text{mol}$
Moles of N: $\frac{51.83\ \text{g}}{14.01\ \text{g/mol}} \approx 3.700\ \text{mol}$

Step3: Find mole ratio (divide by smallest)

Ratio H:C:N = $\frac{3.700}{3.700}:\frac{3.700}{3.700}:\frac{3.700}{3.700} = 1:1:1$

Answer:

C. HCN