# Some substance of the composition CxHyOz contains 54.5 percent carbon, 36.4 percent oxygen

Some substance of the composition CxHyOz contains 54.5 percent carbon, 36.4 percent oxygen, and the vapor density of this substance for hydrogen is 44. Determine the molecular formula of this substance. determine how many molecules and hydrogen atoms are contained in a portion of a given substance weighing 8.8 g

Let’s determine the molar mass of an unknown substance:
M (CxHyOz) = D (H2) • Mr (H2) = 44 • 2 = 88.
The indices of the elements are determined by the formula:
n (e-ta) = W (e-ta) • Mr (in-va) / Ar (e-ta) • 100%.
n (C) = 54.5 • 88/12 • 100% = 4.
n (O) = 36.4 • 88/12 • 100% = 2.
W (H) = 100 – W (C) – W (O) = 100 – 54.5 – 36.4 = 9.1.
n (N) = 9.1 • 88/1 • 100% = 8.
We get the compound С4Н8О2, which corresponds to a molar mass of 88 g / mol, which means that the formula of the substance has been established correctly – it is butanoic (butyric) acid.

Let’s calculate the number of atoms and molecules of hydrogen in 8.8 g of acid.
N (H) = n • NA
n (H) = 8.8 / 1 = 8.8 mol.
N (H) = 8.8 * 6.02 * 10 ^ 23 = 5.3.10 ^ 24. One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.