Question

A sample of a hydrocarbon contains 20.75 g C and 4.25 g H. Its molar mass is 58.04 g/mol. What is its empirical formula C2H5 CH2 CH C5H

Answer 1

Answer : The empirical formula is, $C_2H_5$

Solution : Given,

Mass of C = 20.75 g

Mass of H = 4.25 g

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{20.75g}{12g/mole}=1.73moles$

Moles of H = $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{4.25g}{1g/mole}=4.25moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{1.73}{1.73}=1$

For H = $\frac{4.25}{1.73}=2.5$

The ratio of C : H = 1 : 2.5

In the whole number the ratio of C : H = 2 : 5

The mole ratio of the element is represented by subscripts in empirical formula.

Therefore, the empirical formula is, $C_2H_5$

Answer 2

It is c2h5 if you our doing it on edunitey thats all i can say