Complete combustion of 7.70 g of a hydrocarbon produced 23.7 g of CO2 and 10.9 of H2O. What is the empirical formula of the hydrocarbon?
I first calculated the moles of both the carbon dioxide and the water, but I have no idea where to go from there. Any assistance would be greatly appreciated, thanks!
C3H7
To find the empirical formula of the hydrocarbon, you need to determine the ratio of atoms in the compound based on the masses of the elements involved. Here's how you can approach this problem:
1. Convert the mass of carbon dioxide (CO2) and water (H2O) to moles.
- Moles of CO2 = mass / molar mass of CO2
- Moles of H2O = mass / molar mass of H2O
The molar mass of CO2 is calculated as follows:
- Molar mass of carbon = 12.01 g/mol
- Molar mass of oxygen = 16.00 g/mol (2 atoms in CO2)
- Molar mass of CO2 = 12.01 g/mol + 16.00 g/mol + 16.00 g/mol = 44.01 g/mol
The molar mass of H2O is:
- Molar mass of hydrogen = 1.01 g/mol (2 atoms in H2O)
- Molar mass of oxygen = 16.00 g/mol
- Molar mass of H2O = 1.01 g/mol + 1.01 g/mol + 16.00 g/mol = 18.02 g/mol
Calculate the moles using the given masses:
- Moles of CO2 = 23.7 g / 44.01 g/mol
- Moles of H2O = 10.9 g / 18.02 g/mol
2. Determine the ratio of moles between carbon and hydrogen.
- To get the simplest whole number ratio, divide the number of moles of carbon by the smaller of the two values (moles of hydrogen or carbon).
- This ensures that you have a whole number ratio.
Let's assume the moles of carbon is x and moles of hydrogen is y.
- x / y = Moles of carbon dioxide / Moles of water
Calculate the ratio:
- x / y = (moles of CO2) / (moles of H2O)
3. Determine the empirical formula using the mole ratio.
- The empirical formula represents the simplest whole number ratio of atoms in the compound.
- Convert the ratio you found in step 2 into a whole number ratio by multiplying it by the appropriate factor, if necessary.
For example, if the ratio x/y is 1/2, multiply both sides by 2 to get a whole number ratio of 2/4, which simplifies to 1/2.
4. Report the empirical formula.
- The empirical formula represents the simplest whole number ratio of atoms in the compound.
- Write the formula using the elements and the whole number subscripts representing their ratio.
Follow these steps to find the empirical formula of the hydrocarbon based on the given data.