An unknown compound contains 13.04% of hydrogen, 34.78% of oxygen, and 52.17% of carbon by mass. Determine the empirical formula of the unknown compound. (Atomic mass of O-15.999 g/mol; H-1.008 g/mol; C-12.011g/mol)
C6H12O6
C2H6O
CH2OH
C2H6OH
To determine the empirical formula, we need to find the ratio of the number of atoms of each element in the compound. We can assume a 100g sample of the compound in order to make the percentages into grams.
For 13.04g H, there are 13.04/1.008= 12.94 moles of H
For 34.78g O, there are 34.78/15.999= 2.17 moles of O
For 52.17g C, there are 52.17/12.011= 4.34 moles of C
Now we need to divide each of these mole values by the smallest of these values to get a whole number ratio of the atoms in the compound.
If we divide all mole values by 2.17, the lowest value we obtained, we get:
H: 5.96
O: 1.00
C: 2.00
Dividing each value by the smallest value of 1 gives us:
H: 6
O: 1
C: 2
Therefore, the empirical formula of the unknown compound is C2H6O.
To determine the empirical formula of the unknown compound, we need to calculate the ratio of the different elements present in the compound.
Step 1: Convert the percentages to grams:
For hydrogen (H):
Mass of H = 13.04% mass of unknown compound
= 13.04 g (assuming a 100 g sample)
For oxygen (O):
Mass of O = 34.78% mass of unknown compound
= 34.78 g (assuming a 100 g sample)
For carbon (C):
Mass of C = 52.17% mass of unknown compound
= 52.17 g (assuming a 100 g sample)
Step 2: Convert grams to moles:
For hydrogen (H):
Moles of H = Mass of H / Atomic mass of H
= 13.04 g / 1.008 g/mol
= 12.94 mol
For oxygen (O):
Moles of O = Mass of O / Atomic mass of O
= 34.78 g / 15.999 g/mol
= 2.17 mol
For carbon (C):
Moles of C = Mass of C / Atomic mass of C
= 52.17 g / 12.011 g/mol
= 4.34 mol
Step 3: Find the mole ratios:
Divide the number of moles of each element by the smallest number of moles to obtain whole-number ratios.
H:O:C = 12.94 mol / 2.17 mol / 4.34 mol ≈ 6:1:2
Therefore, the empirical formula of the unknown compound is C6H12O6.