Question

an alcohol is 68.84% c and 4.962% h by mass. the rest is oxygen. what is the empirical formula of the alcohol? enter the elements in the order c, h, and then o.

Explanation:

Step1: Assume the mass of the compound is 100g

So, mass of \(C = 68.84g\), mass of \(H=4.962g\), mass of \(O=(100 - 68.84 - 4.962)g=26.198g\)

Step2: Calculate the number of moles of each element

Molar mass of \(C = 12.01g/mol\), molar mass of \(H = 1.008g/mol\), molar mass of \(O = 16.00g/mol\)
Moles of \(C=\frac{68.84g}{12.01g/mol}\approx5.732mol\)
Moles of \(H=\frac{4.962g}{1.008g/mol}\approx4.923mol\)
Moles of \(O=\frac{26.198g}{16.00g/mol}\approx1.637mol\)

Step3: Divide the number of moles by the smallest number of moles

\(n_{C}=\frac{5.732}{1.637}\approx3.5\), \(n_{H}=\frac{4.923}{1.637}\approx3\), \(n_{O}=\frac{1.637}{1.637} = 1\)
Multiply by 2 to get whole - number ratios: \(n_{C}=7\), \(n_{H}=6\), \(n_{O}=2\)

Answer:

\(C_{7}H_{6}O_{2}\)