Calculate the mass fraction of elements in CO2.

To solve this problem, we write down the given: CO2

Find: w (C) -? w (O) -?

Decision:

Let’s write down the formula for calculating the mass fractions of each chemical element in the substance.

w = n * Ar / Mr

n is the number of atoms or molecules.

Ar is the relative atomic mass of a chemical element.

Mr is the relative molecular weight of the substance.

Let’s calculate the relative molecular weight of carbon dioxide.

Mr (CO2) = 14 + 16 * 2 = 44

w (C) = 1 * 12/44 = 0.27 or 27%

Since the formula for carbon dioxide contains two oxygen atoms, then n = 2

w (O) = 2 * 16/44 = 0.73 or 73%

Answer: w (C) = 0.27 or 27%; w (O) = 0.73 or 73%