Getting empirical formula, but they also gave molar mass too.

Answer:
Empirical formula is PNCl₂
Explanation:
Percent composition means that 100 g of compound has x g of each element.
In 100 g of compound x, we have 26.73 g of P, 12.09 g of N, 61.18 g of Cl.
So, let's make some rules of three:
In 100 g of compound we have 26.73 g of P, 12.09 g of N, 61.18 g of Cl
In 579.43 g of compound we have:
(579.43 . 26.73) / 100 = 155 g of P
(579.43 . 12.09) / 100 = 70 g of N
(579.43 . 61.18) / 100 = 354 g of Cl
Let's convert the mass of the elements in moles.
155 g of P / 30.97 g/mol = 5 P
70 g / 14 g/mol = 5 N
354 g / 35.45 g/mol = 10 Cl
Answer:
The empirical formula has a molar mass of 115.88 g/mol
The molecular formula = P5N5Cl10
Explanation:
Step 1: Data given
Suppose the mass of compound X = 100.0 grams
Compound X contains:
26.73 % phosphorus = 26.73 grams
12.09 % nitrogen = 12.09 grams
61.18 % chlorine = 61.18 grams
Molar mass of phosphorus = 30.97 g/mol
Molar mass of nitrogen = 14.01 g/mol
Molar mass of chlorine = 35.45 g/mol
Step 2: Calculate moles
Mol = mass / molar mass
Mol P = 26.73 grams / 30.97 g/mol
Mol P = 0.8631 moles
Mol N = 12.09 grams / 14.01 g/mol
Mol N = 0.8630 moles
Mol Cl = 61.18 grams / 35.45 g/mol
Mol Cl = 1.726 moles
Step 3: Calculate mol ratio
We divide by the smallest amount of moles
P: 0.8631 moles / 0.8630 = 1
N: 0.8630 moles / 0.8630 moles = 1
Cl: 1.726 / 0.8630 = 2
The empirical formula is PNCl2
The empirical formula has a molar mass of 115.88 g/mol
The compound has a molar mass of 579.43 g/mol
579.43/115.88 = 5
The molecular formula is 5*(PNCl2) = P5N5Cl10