Question: Combustion Of 5.000g Of An Unknown Hydrocarbon Resulted In 15.14g Of CO2 And 7.751g Of H2O. What Is The Empirical

Question

Question: Combustion Of 5.000g Of An Unknown Hydrocarbon Resulted In 15.14g Of CO2 And 7.751g Of H2O. What Is The Empirical formula

Answer 1

Since the compound is a hydrocarbon, it will contain only carbon (C) and hydrogen (H). We will find the moles of each and then find the empirical formula.

moles of C = 15.14 g CO2 x 1 mol CO2 / 44.01 g x 1 mol C / mol CO2 = 0.3440 mols C

moles H = 7.751 g H2O x 1 mol H2O / 18.02 g x 2 mol H / mol H2O = 0.8603 mols H

To get whole numbers, we will divide both by 0.3440:

moles C = 0.3440 / 0.3440 = 1 mol C

moles H = 0.8603 / 0.3440 = 2.50 mols H

To get whole numbers, we will multiply both by 2:

moles C = 1x2 = 2 mols C

moles H = 2.5x2 = 5 mols H

Empirical formula = C₂H₅

Answer 2

To determine the empirical formula of the unknown hydrocarbon, we need to calculate the mole ratios of carbon and hydrogen in the compound.

1. Calculate the number of moles of CO2 produced:

Molar mass of CO2 = (12.01 g/mol * 1) + (16.00 g/mol * 2) = 44.01 g/mol

Number of moles of CO2 = 15.14 g / 44.01 g/mol ≈ 0.3439 moles

2. Calculate the number of moles of H2O produced:

Molar mass of H2O = (1.01 g/mol * 2) + (16.00 g/mol) = 18.02 g/mol

Number of moles of H2O = 7.751 g / 18.02 g/mol ≈ 0.4300 moles

3. Determine the number of moles of carbon and hydrogen in the hydrocarbon:

Number of moles of carbon = 0.3439 moles

Number of moles of hydrogen = 2 * 0.4300 moles = 0.8600 moles

4. Find the mole ratio of carbon to hydrogen:

Mole ratio of carbon to hydrogen = 0.3439 moles / 0.8600 moles ≈ 0.4

5. Determine the empirical formula:

The empirical formula represents the simplest whole-number ratio of atoms in a compound. Since the mole ratio of carbon to hydrogen is approximately 0.4, we can multiply both sides by 2.5 to get a whole number:

Carbon: 0.4 * 2.5 = 1

Hydrogen: 1 * 2.5 = 2.5 ≈ 3

Therefore, the empirical formula of the unknown hydrocarbon is CH3 (1 carbon atom, 3 hydrogen atoms).