Some compound contains 54.50% C, 36.34% O, the rest is hydrogen. Find the true formula of a compound if its density in air is 3.04.

Decision:
The molecular weight of air is 29 g / mol. Let’s calculate the molecular weight of the unknown compound:
29 * 3.04 = 88 g / mol;
The relative atomic mass of carbon is 12, oxygen is 16, and hydrogen is 1.
Find the molecular weight of carbon in the compound:
88 * 0.545 = 48 g / mol;
Let’s find the number of carbon atoms:
48/12 = 4 atoms;
Find the molecular weight of oxygen in the compound:
88 * 0.3634 = 32 g / mol;
Let’s find the number of oxygen atoms:
32/16 = 2 atoms;
Find the molecular weight of hydrogen in the compound:
88 – 48 – 32 = 8 g / mol (the number of hydrogen atoms is 8)
Answer: the molecular formula of the compound is C4H8O2.