Question

A sample of a compound contains 32.0 g C and 8.0 g H. Its molar mass is 30.0 g/mol. What is the compound’s molecular formula?

Answer 1

C2H6

Step-by-step explanation:

Answer 2

Hello!

The answer is: C2H6

Why?

First, we need to find the empirical formula of the compound:

Looking for the relative atomic mass for each element:

`C=12.011g/mol\\H=1.008g/mol`

Finding the number of moles for each element:

`C=32g*(1mole)/(12.011g)=2.67mole\\H=8g*(1mole)/(1.008g)=7.93mole`

Then, we need to determinate the mole ratio by dividing each result into the smallest number:

`C=(2.67)/(2.67)=1\\\\H=(7.93)/(2.67)=2.97=3`

So, the empirical formula would be CH3

We are given the molar mass of the compound is equal to 30 g/mol

We need to compare the empirical formula molecular mass and the molecular formula molar mass in order to find the number of atoms of the compound:

Empirical formula molar mass:

`CH3=12.011+(1.008)*3=15.03g/mol`

Molecular formula molar mass = 30.0 g/mol

So, by dividing the molecular formula molar mass by the empirical formula molar mass we have the number of atoms of the compound:

`(30g/mol)/(15.03g/mol)=2`

Therefore,

The molecular formula will be: (CH3)2= C2H6

Have a nice day!