Question

a compound is found to contain 79.89% c and 20.11% h by mass. determine the empirical and molecular formulas of the compound. the molar mass is about 30 g/mol. question what are the moles of each element in 100.0 g of the compound? mol c mol h

Explanation:

Step1: Calculate moles of C

Molar mass of C is \(12.01\ g/mol\). Mass of C in \(100\ g\) compound is \(79.89\ g\).
Moles of \(C=\frac{79.89\ g}{12.01\ g/mol}\approx 6.65\ mol\)

Step2: Calculate moles of H

Molar mass of H is \(1.008\ g/mol\). Mass of H in \(100\ g\) compound is \(20.11\ g\).
Moles of \(H=\frac{20.11\ g}{1.008\ g/mol}\approx 19.95\ mol\)

Step3: Find the ratio of moles

Divide moles of each element by the smaller number of moles (\(6.65\)).
Ratio for \(C=\frac{6.65}{6.65} = 1\)
Ratio for \(H=\frac{19.95}{6.65}\approx3\)

Answer:

mol C: \(6.65\), mol H: \(19.95\)