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The percent composition by mass of a compound is 49.48% C, 5.19% H, 28.85 % N, and 16.48% O. What is the molecular formula of this compound if its molar mass is 194.19 g/mol

User Drwhite
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Final answer:

The molecular formula of the compound is C4H8N2O4.

Step-by-step explanation:

To determine the molecular formula of the compound, we need to find the empirical formula first. The empirical formula gives the simplest whole number ratio of atoms in a compound. To find the empirical formula, we assume 100 g of the compound, which means we have 49.48 g of carbon, 5.19 g of hydrogen, 28.85 g of nitrogen, and 16.48 g of oxygen. We can convert these masses to moles by dividing by their respective molar masses:

Carbon: 49.48 g * (1 mol/12.01 g) = 4.12 mol

Hydrogen: 5.19 g * (1 mol/1.01 g) = 5.14 mol

Nitrogen: 28.85 g * (1 mol/14.01 g) = 2.06 mol

Oxygen: 16.48 g * (1 mol/16.00 g) = 1.03 mol

We then divide these moles by the smallest number of moles to get the simplest whole number ratio:

Carbon: 4.12 mol / 2.06 mol = 2

Hydrogen: 5.14 mol / 2.06 mol = 2

Nitrogen: 2.06 mol / 2.06 mol = 1

Oxygen: 1.03 mol / 1.03 mol = 1

The empirical formula of the compound is CH2NO. The molar mass of this empirical formula is calculated as:

(12.01 g/mol * 2) + (1.01 g/mol * 2) + (14.01 g/mol * 1) + (16.00 g/mol * 1) = 45.04 g/mol

To find the molecular formula, we divide the molar mass of the compound (194.19 g/mol) by the molar mass of the empirical formula (45.04 g/mol): 194.19 g/mol / 45.04 g/mol = 4.32

Rounding to the nearest whole number, the molecular formula of the compound is C4H8N2O4.

User Mlepage
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