calculate the empirical formula for an unknown compound from the following information: C= 39.2%, H= 8.73% and O= 52.1%
Take a 100 g sample which will give you
39.2g C
8.73 g H
52.1 g O
Convert grams to mols. mols = grams/molar mass
Find ratio of elements to each other with the smallest number being 1.00. The each way to do that is to divide the smallest number by its self, then divide the other numbers by the same small number. I think you will need to find a common multiplier to obtain whole numbers. Post your work if you get stuck.
i got it... thank you
To calculate the empirical formula for an unknown compound, we need to determine the ratio of the elements present in the compound.
Step 1: Convert the percentages to grams:
Assuming we have 100 grams of the compound, we can calculate the grams of each element based on the given percentages:
C: 39.2 g (39.2% of 100 g)
H: 8.73 g (8.73% of 100 g)
O: 52.1 g (52.1% of 100 g)
Step 2: Convert the grams to moles:
To find the number of moles of each element, we need to divide the grams of each element by their respective molar masses.
The molar mass of carbon (C) is approximately 12.01 g/mol, the molar mass of hydrogen (H) is approximately 1.01 g/mol, and the molar mass of oxygen (O) is approximately 16.00 g/mol.
Number of moles of C = 39.2 g / 12.01 g/mol ≈ 3.26 mol
Number of moles of H = 8.73 g / 1.01 g/mol ≈ 8.64 mol
Number of moles of O = 52.1 g / 16.00 g/mol ≈ 3.26 mol
Step 3: Determine the ratios:
Divide each mole value by the smallest mole value to obtain the simplest, whole number ratio.
Dividing by the smallest mole value (3.26 mol), we get:
Number of moles of C ≈ 3.26 mol / 3.26 mol = 1
Number of moles of H ≈ 8.64 mol / 3.26 mol ≈ 2.65
Number of moles of O ≈ 3.26 mol / 3.26 mol = 1
Step 4: Write the empirical formula:
Using the whole number ratios obtained, we can write the empirical formula for the compound.
The empirical formula is C₁H₂.65O₁, which can be simplified to CH₂O.
Therefore, the empirical formula for the unknown compound is CH₂O.