In an experiment 3.10g of a compound of carbon, hydrogen and oxygen produce 4.4g of C02 and 2.7g of water on complete combustion. Determine the empirical formula of the compound
( C=12.0, O=16.0 H=1.0)
https://www.jiskha.com/questions/1014597/An-unknown-compound-contains-only-carbon-hydrogen-and-oxygen-CxHxOx-Combustion
Well, let's get empirical! To determine the empirical formula, we need to find the mole ratio of the elements in the compound.
First, let's calculate the number of moles of carbon dioxide (CO2) produced. Using the molar mass of carbon dioxide (44.01 g/mol), we divide the mass of CO2 (4.4 g) by the molar mass to find the number of moles:
4.4 g CO2 / 44.01 g/mol = 0.1 mol CO2
Next, let's calculate the number of moles of water (H2O) produced. Using the molar mass of water (18.02 g/mol), we divide the mass of water (2.7 g) by the molar mass to find the number of moles:
2.7 g H2O / 18.02 g/mol = 0.15 mol H2O
Now, let's find the number of moles of carbon (C) in the compound. Since one molecule of carbon dioxide (CO2) contains one atom of carbon (C), the mole ratio of carbon to carbon dioxide is 1:1. Therefore, the number of moles of carbon is the same as the number of moles of carbon dioxide: 0.1 mol C.
Lastly, let's find the number of moles of hydrogen (H) in the compound. Since one molecule of water (H2O) contains two atoms of hydrogen (H), the mole ratio of hydrogen to water is 2:1. Therefore, the number of moles of hydrogen is twice the number of moles of water: 2 * 0.15 mol = 0.3 mol H.
Now, let's calculate the number of moles of oxygen (O) in the compound. Since carbon dioxide (CO2) and water (H2O) are the only sources of oxygen in the combustion, we can determine the number of moles of oxygen by subtracting the moles of carbon and hydrogen from the total moles in the compound:
Total moles - moles of C - moles of H = moles of O
0.1 mol - 0.1 mol - 0.3 mol = -0.3 mol
Uh-oh! It seems like we have a negative number of moles for oxygen, which doesn't make any sense. This can happen due to experimental errors or incomplete combustion. Unfortunately, this means we can't accurately determine the empirical formula based on the given data. It's time to call in the scientific circus for further investigation! 🎪🔬
To find the empirical formula of the compound, we need to determine the ratio of the elements in the compound using the given mass of each element.
1. Calculate the moles of carbon dioxide (CO2) produced:
- Mass of CO2 = 4.4g
- Molar mass of CO2 = 12.0g/mol (C) + 16.0g/mol (O) = 44.0g/mol
- Moles of CO2 = Mass of CO2 / Molar mass of CO2 = 4.4g / 44.0g/mol = 0.1 mol
2. Calculate the moles of water (H2O) produced:
- Mass of H2O = 2.7g
- Molar mass of H2O = 2.0g/mol (H) + 16.0g/mol (O) = 18.0g/mol
- Moles of H2O = Mass of H2O / Molar mass of H2O = 2.7g / 18.0g/mol = 0.15 mol
3. Calculate the moles of carbon, hydrogen, and oxygen present in the compound:
- Moles of carbon = moles of CO2 = 0.1 mol
- Moles of hydrogen = 2 * moles of H2O = 2 * 0.15 mol = 0.3 mol
- Moles of oxygen = 4 * moles of CO2 + moles of H2O = 4 * 0.1 mol + 0.15 mol = 0.55 mol
4. Determine the empirical formula:
- Divide the moles by the smallest number of moles (0.1 mol):
- Moles of carbon = 0.1 mol / 0.1 mol = 1
- Moles of hydrogen = 0.3 mol / 0.1 mol = 3
- Moles of oxygen = 0.55 mol / 0.1 mol = 5.5
- Round the subscripts to the nearest whole number:
- Empirical formula: CH3O5.5
However, we cannot have a fraction in the empirical formula. To convert the fractional number to a whole number, multiply all the subscripts by 2:
- Empirical formula: C2H6O11
Therefore, the empirical formula of the compound is C2H6O11.
To determine the empirical formula of a compound, we need to find the simplest ratio of the elements present. Here's how you can calculate it step by step:
1. Determine the masses of carbon, hydrogen, and oxygen in the compound:
- Carbon: Given that the mass of CO2 produced is 4.4g, and carbon has a molar mass of 12.0 g/mol, you can calculate the mass of carbon by multiplying the molar mass of carbon by the number of moles of CO2 produced.
Mass of carbon = 12.0 g/mol × (4.4 g / 44.0 g/mol) = 1.2 g
- Hydrogen: Given that the mass of H2O produced is 2.7g, and hydrogen has a molar mass of 1.0 g/mol, you can calculate the mass of hydrogen by multiplying the molar mass of hydrogen by the number of moles of H2O produced.
Mass of hydrogen = 1.0 g/mol × (2.7 g / 18.0 g/mol) = 0.15 g
- Oxygen: The total mass of the compound can be calculated by subtracting the masses of carbon and hydrogen from the initial mass of the compound.
Mass of oxygen = 3.10 g - (1.2 g + 0.15 g) = 1.75 g
2. Calculate the number of moles for each element:
Number of moles = mass / molar mass
- Moles of carbon = 1.2 g / 12.0 g/mol = 0.10 mol
- Moles of hydrogen = 0.15 g / 1.0 g/mol = 0.15 mol
- Moles of oxygen = 1.75 g / 16.0 g/mol = 0.109375 mol
3. Divide the number of moles for each element by the smallest number of moles to get the simplest whole-number ratio:
Since the smallest number of moles is 0.10 mol, divide the moles of each element by 0.10 mol.
- Carbon: 0.10 mol / 0.10 mol = 1 mol
- Hydrogen: 0.15 mol / 0.10 mol = 1.5 mol
- Oxygen: 0.109375 mol / 0.10 mol ≈ 1.1 mol
4. Convert the ratio to the simplest whole-number ratio by multiplying all the ratios by 2 (if necessary) to obtain whole numbers:
- Carbon: 1 × 2 = 2
- Hydrogen: 1.5 × 2 ≈ 3
- Oxygen: 1.1 × 2 ≈ 2
Therefore, the empirical formula of the compound is C2H3O2.