Question

What is the empirical formula of an unknown compound if was determined by a laboratory experiment that it is made up of 27% by mass of Carbon and 73% by mass of Oxygen?

Answer 1

Answer:

water

Explanation:

Answer 2

Answer: The empirical formula for the given compound is $CO_2$

Explanation:

We are given:

Percentage of C = 27 %

Percentage of O = 73 %

Let the mass of compound be 100 g. So, percentages given are taken as mass.

Mass of C = 27 g

Mass of O = 73 g

To formulate the empirical formula, we need to follow some steps:

• Step 1: Converting the given masses into moles.

Moles of Carbon =$\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{27g}{12g/mole}=2.25moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{73g}{16g/mole}=4.56moles$

• Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 2.25 moles.

For Carbon = $\frac{2.25}{2.25}=1$

For Oxygen = $\frac{4.56}{2.25}=2.02\approx 2$

• Step 3: Taking the mole ratio as their subscripts.

The ratio of C : O = 1 : 2

Hence, the empirical formula for the given compound is $CO_2$