Question

How do u calculate the empirical formulae of an unknown compound A if it contains 46.6% of Carbon, 13.6% of Nitrogen, 8.47% of Hydrogen and ?% of Oxygen???? NB: RAM of C= 12, H= 1, N= 14 and O= 16

Answer 1

C₄NH₉O₂

Step-by-step explanation:

The question requires we determine the empirical for an unknown compound A.

• We are given percentages of elements in the compound;

Carbon-46.6%

Nitrogen - 13.6%

Hydrogen - 8.47%

Oxygen = 100% - (46.65 + 13.6% + 8.47%)

= 31.28%

• Assuming the sample of the unknown compound is 100 g

Step 1: Determine the moles of each element

Moles of Carbon = 46.6 ÷ 12

= 3.88 moles

Moles of Nitrogen = 13.6 ÷ 14

= 0.971 moles

Moles of Hydrogen = 8.47 ÷ 1

= 8.47 moles

Moles of Oxygen = 31.28 ÷ 16

= 1.955 moles

Step 2: Determine the mole ratio of the elements

Mole ratio = C : N : H : O

= 3.88 moles : 0.971 moles : 8.47 moles : 1.955 moles

We divide by the smallest (0.971 moles )

= 3.99 : 1 : 8.72 : 2.01

= 4 : 1 : 9 : 2

E.F = C₄NH₉O₂

Therefore, the empirical formula of compound A is C₄NH₉O₂