Question

A laboratory analysis produced the following mass percent data: $48.5C,3.9H$, and $47.5O$.
Find the empirical formula of the compound.

• A. $CHO$
• B. $C_4{H}_4{O}_3$
• C. $C_2{H}_{2}O$
• D. $C_{12}H{O}_8$

Answer 1

The correct option is A $CHO$

1) Assume 100 g of the compound is present. This changes the percents to grams:

C ⇒ 48.5 g
H ⇒ 3.9 g
O ⇒ 47.5 g

2) Convert the masses to moles:

C ⇒ 48.5 g / 12 = 4.4
H ⇒ 3.9 g / 1 = 3.9
O ⇒ 47.5 g / 16 = 3

3) Divide by the lowest, seeking the smallest whole-number ratio:

C ⇒ 4 / 3 = 1
H ⇒ 3.9 / 3.9 = 1
O ⇒ 3 / 3 = 1

4) Write the empirical formula:

CHO

5) Determine the molecular formula:

"EFW" ⇒ 48.5+3.9+47.5 = 74

96.3 / 96= 1

molecular formula = CHO