0.2500 g of a known compound was subjected to combustion. 0.1500 g of water and 0.3664 g of carbon dioxide were produced. Determine the empirical formula of this compound?. Note the known compound contains C, H and O. (Molar mass: N=14 g/mol; C=12 g/mol; O = 16 g/mol)
To determine the empirical formula, we need to find the ratio of the number of atoms of each element in the compound.
First, we need to find the number of moles of water and carbon dioxide produced:
moles of water = (0.1500 g) / (18.015 g/mol) = 0.008324 mol
moles of carbon dioxide = (0.3664 g) / (44.01 g/mol) = 0.008328 mol
The number of carbon atoms in the known compound can be found from the moles of carbon dioxide produced (since each molecule of CO2 contains one carbon atom):
number of carbon atoms = 0.008328 mol
The number of hydrogen atoms in the known compound can be found from the moles of water produced (since each molecule of water contains two hydrogen atoms):
number of hydrogen atoms = 2 x 0.008324 mol = 0.016648 mol
The number of oxygen atoms in the known compound can be found by subtracting the number of carbon and hydrogen atoms from the total number of atoms produced:
number of oxygen atoms = (0.008328 mol x 2) - 0.016648 mol = 0.000008 mol
Next, we need to convert the number of atoms to whole numbers by dividing by the smallest number of atoms (in this case, the number of oxygen atoms):
ratio of carbon atoms = 0.008328 mol / 0.000008 mol = 1035
ratio of hydrogen atoms = 0.016648 mol / 0.000008 mol = 2081
Finally, we can write the empirical formula by dividing the ratios by their greatest common factor:
empirical formula = C1H2O
To determine the empirical formula of the compound, we need to find the ratio of the elements present in the compound.
First, let's calculate the number of moles of water (H2O) and carbon dioxide (CO2) produced:
Number of moles of water = mass of water / molar mass of water
= 0.1500 g / 18.015 g/mol
≈ 0.00832 mol
Number of moles of carbon dioxide = mass of carbon dioxide / molar mass of carbon dioxide
= 0.3664 g / 44.01 g/mol
≈ 0.00832 mol
Now, let's determine the number of moles of carbon and hydrogen in the compound.
Number of moles of carbon = number of moles of carbon dioxide
= 0.00832 mol
Number of moles of hydrogen = number of moles of water × 2
= 0.00832 mol × 2
= 0.01664 mol
Next, we need to calculate the number of moles of oxygen in the compound.
Number of moles of oxygen = molar mass of the compound - (number of moles of carbon + number of moles of hydrogen)
= 0.2500 g / molar mass of the compound - (0.00832 mol + 0.01664 mol)
= 0.2500 g / molar mass of the compound - 0.02496 mol
Since the ratio of the elements in the empirical formula is the simplest whole number ratio, we need to convert the number of moles to the smallest whole number ratio.
Divide all the moles by the smallest number of moles.
0.00832 mol / 0.00832 mol ≈ 1
0.01664 mol / 0.00832 mol ≈ 2
0.2500 g / molar mass of the compound - 0.02496 mol / 0.00832 mol
The empirical formula of the compound is CH2O.