Chemistry percent yield

Question

Gaseous butane  reacts with gaseous oxygen gas to produce gaseous carbon dioxide and gaseous water. If 

8.78g of carbon dioxide is produced from the reaction of 

11.6g of butane and 65.3g of oxygen gas, calculate the percent yield of carbon dioxide. 

Answer 1

first need to determine the theoretical yield of carbon dioxide based on the balanced chemical equation and then compare it to the actual yield obtained from the experiment.

The balanced chemical equation for the reaction between butane (C4H10) and oxygen gas (O2) to produce carbon dioxide (CO2) and water (H2O) is:

2 C4H10 + 13 O2 -> 8 CO2 + 10 H2O

Given:

Mass of carbon dioxide produced (actual yield) = 8.78 g

Mass of butane used = 11.6 g

Mass of oxygen gas used = 65.3 g

Step 1: Calculate the moles of each reactant (butane and oxygen gas).

Molar mass of butane (C4H10) = 4 * atomic mass of carbon + 10 * atomic mass of hydrogen

Molar mass of butane (C4H10) = 4 * 12.01 g/mol + 10 * 1.01 g/mol

Molar mass of butane (C4H10) = 58.14 g/mol

Moles of butane = Mass of butane / Molar mass of butane

Moles of butane = 11.6 g / 58.14 g/mol ≈ 0.1995 mol (rounded to four decimal places)

Molar mass of oxygen gas (O2) = 2 * atomic mass of oxygen

Molar mass of oxygen gas (O2) = 2 * 16.00 g/mol

Molar mass of oxygen gas (O2) = 32.00 g/mol

Moles of oxygen gas = Mass of oxygen gas / Molar mass of oxygen gas

Moles of oxygen gas = 65.3 g / 32.00 g/mol ≈ 2.0406 mol (rounded to four decimal places)

Step 2: Determine the limiting reactant.

The stoichiometric ratio between butane and oxygen gas is 2:13 based on the balanced chemical equation. This means that for every 2 moles of butane, 13 moles of oxygen gas are required.

Let's check which reactant is limiting:

For butane: Moles of CO2 produced = 8 * (Moles of butane) / 2 ≈ 8 * 0.1995 / 2 ≈ 0.798 mol

For oxygen gas: Moles of CO2 produced = 8 * (Moles of oxygen gas) / 13 ≈ 8 * 2.0406 / 13 ≈ 1.244 mol

The moles of CO2 produced are less when calculated from the moles of butane. Therefore, butane is the limiting reactant.

Step 3: Calculate the theoretical yield of carbon dioxide (CO2) based on the limiting reactant.

Moles of CO2 produced (theoretical yield) = 8 * (Moles of butane) / 2

Moles of CO2 produced (theoretical yield) = 8 * 0.1995 / 2 ≈ 0.798 mol

Mass of CO2 produced (theoretical yield) = Moles of CO2 * Molar mass of CO2

Mass of CO2 produced (theoretical yield) = 0.798 mol * 44.01 g/mol ≈ 35.091 g (rounded to three decimal places)

Step 4: Calculate the percent yield of carbon dioxide.

Percent Yield = (Actual Yield / Theoretical Yield) * 100

Percent Yield = (8.78 g / 35.091 g) * 100 ≈ 25.07%

The percent yield of carbon dioxide is approximately 25.07%.