Question

of a certain Compound X, known to be made of carbon, hydrogen and perhaps oxygen, and to have a molecular molar mass of 128./gmol, is burned completely in excess oxygen, and the mass of the products carefully measured: product mass carbon dioxide 22.35g water 3.66g Use this information to find the molecular formula of X.

Answer 1

Answer: C5H4O4

Step-by-step explanation:

First, find how many moles of Carbon and Hydrogen we know we have from these reactions.

The molar mass of Carbon Dioxide is 44g, so we have 0.508 moles CO2 and therefore 0.508 moles of Carbon from the original compound.

The molar mass of Water is 18g, so we have 0.203 moles of H2O, and we double the amount of moles of hydrogen because there are two hydrogens per water molecule, so 0.406 moles of hydrogen.

This gives us a ratio of moles 0.508:0.406:X, where X is moles of oxygen. 0.508/0.406 is 1.25 so this ratio is 5:4:X.

We now know how many moles of Carbon and Hydrogen are in the compound and the molar mass of the compound and can plug in values.

5(molar mass carbon) + 4(molar mass of hydrogen) + X(molar mass of oxygen) = 128g
5(12) + 4(1) + X(16) = 128

X=4

So, the formula is C5H4O4.