A compound contains 53.3% carbon, 11.1% hydrogen, and 35.6% oxygen by mass. If its molar mass is 180 g/mol, determine its molecular formula.
Guide On Rating System
Vote
To determine the molecular formula of the compound, we need to find the empirical formula first.
We'll assume we have 100g of the compound.
The mass of carbon in the compound is 53.3g.
The mass of hydrogen in the compound is 11.1g.
The mass of oxygen in the compound is 35.6g.
We'll convert these masses into moles using the molar masses of each element:
The molar mass of carbon is 12.01 g/mol, so the number of moles of carbon is 53.3g / 12.01g/mol = 4.443mol.
The molar mass of hydrogen is 1.008 g/mol, so the number of moles of hydrogen is 11.1g / 1.008g/mol = 11.01mol.
The molar mass of oxygen is 16.00 g/mol, so the number of moles of oxygen is 35.6g / 16.00g/mol = 2.225mol.
To find the empirical formula, we'll divide the number of moles of each element by the smallest number of moles:
Carbon: 4.443mol / 2.225mol = 2
Hydrogen: 11.01mol / 2.225mol = 4.956 (approximately 5)
Oxygen: 2.225mol / 2.225mol = 1
So the empirical formula of the compound is C2H5O.
To find the molecular formula, we'll need to know the molar mass of the empirical formula:
C2H5O has a molar mass of 2(12.01 g/mol) + 5(1.008 g/mol) + 16.00 g/mol = 44.10 g/mol.
To find the multiplier that will give the molar mass of 180 g/mol, we'll divide the molar mass of the desired compound by the molar mass of the empirical formula:
180 g/mol / 44.10 g/mol = 4.08 (approximately 4).
Therefore, the molecular formula of the compound is (C2H5O)4, or C8H20O4.
Got a question with my answer?
Cheapmath.com is completely free!
Asking question is free.
Getting answers is free.
+99