Question

Дано : w(C)=54,4% w(H)=9,1% w(O)=36,4% D(H2)=44 CxHyOz-?

Answer 1

To determine the molecular formula of the compound CxHyOz, given the percentage composition of each element, we can follow these steps:

Step 1: Convert the percentages to masses (in grams) of each element in a 100-gram sample of the compound. Step 2: Find the molar ratios of the elements. Step 3: Divide each molar ratio by the smallest one to get the simplest whole-number ratio of the elements. Step 4: Express the ratio in terms of x, y, and z.

Given percentages: w(C) = 54.4% w(H) = 9.1% w(O) = 36.4%

Step 1: Calculate the masses of each element in a 100-gram sample of the compound.

Mass of C = 54.4% of 100 grams = 54.4 grams Mass of H = 9.1% of 100 grams = 9.1 grams Mass of O = 36.4% of 100 grams = 36.4 grams

Step 2: Find the molar ratios of the elements.

Molar mass of C (M_C) = 12.01 g/mol Molar mass of H (M_H) = 1.008 g/mol Molar mass of O (M_O) = 16.00 g/mol

Moles of C (n_C) = Mass of C / M_C = 54.4 g / 12.01 g/mol ≈ 4.531 moles Moles of H (n_H) = Mass of H / M_H = 9.1 g / 1.008 g/mol ≈ 9.03 moles Moles of O (n_O) = Mass of O / M_O = 36.4 g / 16.00 g/mol ≈ 2.275 moles

Step 3: Divide each molar ratio by the smallest one to get the simplest whole-number ratio.

Divide all the moles by 2.275 (the smallest number of moles):

n_C / 2.275 ≈ 4.531 / 2.275 ≈ 1.99 n_H / 2.275 ≈ 9.03 / 2.275 ≈ 3.97 n_O / 2.275 ≈ 2.275 / 2.275 ≈ 1.00

Step 4: Express the ratio in terms of x, y, and z.

The simplest whole-number ratio of C, H, and O is approximately 2:4:1.

Therefore, the molecular formula of the compound is C2H4O.