Assuming the relative molecular mass of a compound with empirical formula C2H4NO is 116. What is the molecular formula
To find the molecular formula, we need to first calculate the empirical formula's mass.
Empirical formula mass = (2 x atomic mass of C) + (4 x atomic mass of H) + (atomic mass of N) + (atomic mass of O)
Empirical formula mass = (2 x 12.01) + (4 x 1.01) + 14.01 + 16.00 = 42.03 g/mol
Now, we can use the given relative molecular mass to determine the molecular formula:
Relative molecular mass (M) = n x empirical formula mass
where n is the number of empirical formula units in the molecular formula.
n = M / empirical formula mass = 116 / 42.03 = 2.76
Since we cannot have a fraction of a molecule, we round n to the nearest whole number. Therefore, the molecular formula is:
Molecular formula = n x empirical formula
Molecular formula = 3 x C2H4NO
Molecular formula = C6H12N2O3
To determine the molecular formula of a compound, we need to know its empirical formula and the relative molecular mass (also known as the molar mass or molecular weight).
The empirical formula gives us the simplest ratio of atoms in the compound, while the molecular formula provides the actual number of atoms in each element present in the molecule.
To find the molecular formula from the empirical formula, we follow these steps:
Step 1: Calculate the empirical formula mass.
- Find the molar mass of each element in the empirical formula: C = 12 g/mol, H = 1 g/mol, N = 14 g/mol, O = 16 g/mol.
- Multiply the number of atoms of each element in the empirical formula by their respective molar masses and add them together to get the empirical formula mass.
Empirical formula mass = (2 * C) + (4 * H) + N + O.
Step 2: Calculate the ratio between the molecular mass and empirical formula mass.
- Divide the relative molecular mass given in the problem (116 g/mol) by the empirical formula mass calculated in Step 1.
Step 3: Determine the whole-number ratio.
- By comparing the ratio obtained in Step 2 to the simplest ratio of atoms in the empirical formula, we can determine the whole-number ratio that converts the empirical formula to the molecular formula.
Step 4: Determine the molecular formula.
- Multiply the subscripts in the empirical formula by the whole-number ratio determined in Step 3 to obtain the molecular formula.
Let's calculate the molecular formula using these steps:
Step 1: Calculate the empirical formula mass.
- C = 12 g/mol, H = 1 g/mol, N = 14 g/mol, O = 16 g/mol.
- Empirical formula mass = (2 * 12) + (4 * 1) + 14 + 16 = 44 g/mol.
Step 2: Calculate the ratio between the molecular mass and empirical formula mass.
- Molecular mass / Empirical formula mass = 116 g/mol / 44 g/mol = 2.64.
Step 3: Determine the whole-number ratio.
- The ratio obtained from Step 2, 2.64, is approximately 3.
- This means that the molecular formula has approximately three times the number of atoms compared to the empirical formula.
Step 4: Determine the molecular formula.
- Multiply the subscripts in the empirical formula (C2H4NO) by the whole-number ratio, 3.
Molecular formula = (C2H4NO)3 = C6H12N3O3.
Therefore, based on the given relative molecular mass of 116, the molecular formula is C6H12N3O3.
To determine the molecular formula, we need to find the empirical formula first. The empirical formula represents the simplest whole number ratio of atoms in a compound.
Given that the empirical formula of the compound is C2H4NO, we need to find the empirical mass of this formula. We can do this by adding up the atomic masses of each element in the formula:
C: 2 x atomic mass of C = 2 x 12.01 g/mol = 24.02 g/mol
H: 4 x atomic mass of H = 4 x 1.01 g/mol = 4.04 g/mol
N: 1 x atomic mass of N = 1 x 14.01 g/mol = 14.01 g/mol
O: 1 x atomic mass of O = 1 x 16.00 g/mol = 16.00 g/mol
Empirical mass = 24.02 + 4.04 + 14.01 + 16.00 = 58.07 g/mol
Now, to find the molecular formula, we divide the relative molecular mass (116) by the empirical mass (58.07):
116 g/mol / 58.07 g/mol = 2
This means that the molecular formula is two times the empirical formula. Therefore, the molecular formula for the compound is C4H8N2O2.