Question

You find that 7.36g of a compound has decomposed to give 6.93g of oxygen. The only other element is hydrogen. If the molar mass of the compound is 34.0g/mol, what is its molecular formula?

Answer 1

Answer:

The molecular formula of this compound is $H_{2}O_{2}$

Explanation:

From the given,

Mass of compound = 7.36 g

Molar mass of compound = 34.0 g/mol

The mass of oxygen = 6.93 g

The hydrocarbon contains only hydrogen and carbon.

Mass of hydrogen + Mass of oxygen = 7.36 g

Mass of hydrogen + 6.93 g = 7.36 g

Mass of hydrogen = 7.36 - 6.93 = 0.43g

Molar mass of hydrogen = 1.0 g/mol

Molar mass of oxygen = 16 g/mol

$Number\,of\,moles\,of \,Oxygen=6.93g\times\frac{1}{16}=0.43mol$

$Number\,of\,moles\,of \,hydrogen=0.43g\times\frac{1}{1}=0.43mol$

Now divided each one by 0.43

Oxygen:

$\frac{0.43}{0.43}=1$

Hydrogen :

$\frac{0.43}{0.43}=1$