Question

Hexamethylene is one of the materials used to produce a type of nylon. It is composed of 62.1% C, 13.% H, and 24.1% N. Its molecular weight is 116 g/mol. What is its molecular formula?

Answer 1

we have mass of each elements as:

C: 62.1 g

H: 13.8 g

N: 24.1 g

Divide by molar mass to get number of moles of each:

C: 62.1/12.01 = 5.1707

H: 13.8/1.008 = 13.6905

N: 24.1/14.01 = 1.7202

Divide by smallest to get simplest whole number ratio:

C: 5.1707/1.7202 = 3

H: 13.6905/1.7202 = 8

N: 1.7202/1.7202 = 1

  

So empirical formula is:

C3H8N

Molar mass of C3H8N,

MM = 3*MM(C) + 8*MM(H) + 1*MM(N)

= 3*12.01 + 8*1.008 + 1*14.01

= 58.104 g/mol

Now we have:

Molar mass = 166.0 g/mol

Empirical formula mass = 58.104 g/mol

Multiplying factor = molar mass / empirical formula mass

= 166.0/58.104

= 3

Hence the molecular formula is : C9H24N3