Question

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

Answer 1

First solve the moles of oxgen present in the compound

mol O = 6.93 g O ( 1 mol O / 16 g O )
mol O = 0.43 mol H

then solve the moles of hydrogen present
mol H = ( 7.36 - 6.93) g H ( 1 mol H / 1 g H)
mol H = 0.43 mol H
so the O and H are in the same mole content so the molecular formula would be OH, but the molar mass will not satisfy. so the answer would be
H2O2

Answer 2

Answer:

H2O2.

Explanation:

Okay, from the question we can see that the compound contains only two elements, that is, Hydrogen and Oxygen. Also,in the question we have some parameters, they are;

Mass of the Compound = 7.36 grams.

The compound decomposed to give Oxygen, the mass of the oxygen is equal to 6.93 grams.

The first thing to do is to determine the number of moles. The number of moles will now be used to determine the molecular formula of the compound.

To calculate the number of moles,n we need the formula below:

Number of moles,n= mass(in grams)/molar mass (In grams per mol). -----------------------------------------(1).

===> Numbers of moles,n= 6.93 grams ÷ 16 grams per mole.

==> 0.433125 mol of oxygen

So, the total mass of the compound= mass of Hydrogen + mass of Oxygen. -----------------------------------------------------(2).

7.36 grams = mass of Hydrogen + 6.93 grams.

==> Mass of Hydrogen = 7.36 grams - 6.93 grams = 0.43 grams.

Using equation (1), the number of moles of Hydrogen: Molar mass of

===>0.43/ 1.00784 grams per mol.

= 0.43 mol.

Hence, there is a need for us to divide both moles by the smaller but since we both are the same, we will just pick on. Therefore, for oxygen and hydrogen it is going to be 1:1.

So, (16+1) b = 34 g/mol

===> 34/17=b= 2.

Hence, 2{OH} = H2O.

The decomposition Reaction is given below;

2 H2O2 --------> 2 H2O + O2