If a compound's empirical formula is CH2O and its' formula mass is 120.12 amu, what is its' molecular formula
CH2O = what for empirical formula mass?
C= about 12
H = about 2
O = about 16
Total = about 30
120.12/30 = 4 so the molecular formula is
(CH2O)4 or C4H8O4.
To find the molecular formula from the empirical formula, we need to know the molar mass of the compound.
The empirical formula CH2O suggest that the compound contains 1 carbon (C), 2 hydrogens (H), and 1 oxygen (O) atom.
The molar mass of the empirical formula can be calculated as follows:
(1 * atomic mass of C) + (2 * atomic mass of H) + (1 * atomic mass of O)
= (1 * 12.01 g/mol) + (2 * 1.01 g/mol) + (1 * 16.00 g/mol)
= 12.01 g/mol + 2.02 g/mol + 16.00 g/mol
= 30.03 g/mol
Given that the formula mass of the compound is 120.12 amu, we can calculate the number of empirical formula units in one mole ( Avogadro's number) using this formula mass:
Number of empirical formula units in one mole = 120.12 g/mol / 30.03 g/mol
= 4
This means that there are four empirical formula units in one mole of the compound.
Therefore, the molecular formula is four times that of the empirical formula:
Empirical formula: CH2O
Molecular formula: (CH2O)4
So, the molecular formula of the compound is C4H8O4.
To determine the molecular formula of a compound given its empirical formula and formula mass, we need to find the ratio between the empirical formula mass and the actual formula mass.
The empirical formula CH2O has an empirical formula mass of 12.01 g/mol (for carbon) + 2(1.01 g/mol) (for hydrogen) + 16.00 g/mol (for oxygen) = 30.03 g/mol.
To find the ratio between the empirical formula mass and the actual formula mass, we divide the formula mass by the empirical formula mass:
Ratio = Actual formula mass / Empirical formula mass
= 120.12 amu / 30.03 g/mol
Note: We need to convert the formula mass from amu to g/mol to match the units of the empirical formula mass.
To convert amu to g/mol, we use the molar mass constant (1 g/mol = 1 amu) since the ratio for elements is 1:1.
Ratio = 120.12 g/mol / 30.03 g/mol
= 4
This means that the molecular formula consists of four times the number of atoms as the empirical formula.
Therefore, the molecular formula is (CH2O)4, which simplifies to C4H8O4.