Calculation of Molecular Weight of Compound Containing 20% Nitrogen

Step 1: Determine the Atomic Weights of the Elements Present
To determine the molecular weight of a compound containing nitrogen, we need to know the atomic weight of nitrogen. The atomic weight of nitrogen is 14.01 g/mol.

Step 2: Calculate the Molecular Weight by Determining the Empirical Formula
To determine the empirical formula of a compound containing nitrogen, we need to know the mass percent of nitrogen in the compound. The mass percent of nitrogen in the compound is given as 20%.

We can assume that we have 100 g of the compound, which means that we have 20 g of nitrogen in the compound. To calculate the number of moles of nitrogen in the compound, we can use the following formula:

Number of moles of nitrogen = Mass of nitrogen / Atomic weight of nitrogen
Number of moles of nitrogen = 20 g / 14.01 g/mol = 1.43 mol

We can then assume that the compound contains one mole of nitrogen and calculate the mass of the other element present in the compound. If we assume that the other element is carbon, then the mass of carbon in the compound is:

Mass of carbon = Mass of compound - Mass of nitrogen
Mass of carbon = 100 g - 20 g = 80 g

To calculate the number of moles of carbon in the compound, we can use the following formula:

Number of moles of carbon = Mass of carbon / Atomic weight of carbon

Assuming that the atomic weight of carbon is 12.01 g/mol, we can calculate the number of moles of carbon in the compound:

Number of moles of carbon = 80 g / 12.01 g/mol = 6.66 mol

We can then divide the number of moles of each element by the smallest number of moles to get the empirical formula of the compound:

Empirical formula = C4H7N

Step 3: Determine the Molecular Formula by Determining the Molecular Weight
To determine the molecular formula of the compound, we need to know the molecular weight of the compound. The empirical formula of the compound is C4H7N, which has a molecular weight of 81.11 g/mol.

If we assume that the molecular weight of the compound is n times the empirical formula weight, then we can write the following equation:

Molecular weight = n x Empirical formula weight

Solving for n, we get:

n = Molecular weight / Empirical formula weight
n = Molecular weight / 81.11 g/mol

We know that the compound contains 20% nitrogen, which means that it contains 1.43 mol of nitrogen per mole of compound. If we assume that the molecular formula of the compound is CxHyNz, then we can write the following equation:

n x Empirical formula weight = (x x 12.01 g/mol) + (y x 1.01 g/mol) + (z x 14.01 g/mol)

Substituting the values we have calculated, we get:

n x 81.11 g/mol = (x x 12.01 g/mol) + (y x 1.01 g/mol) + (1.43 mol x 14.01 g/mol)

Solving for