Question

In a chemical reaction, sulfur (S8) combines with copper to give a pure compound. If you start with 1.000 g of sulfur (S8) and obtain 4.963 g of pure compound. What is the empirical formula of this compound?

Answer 1

Answer: The empirical formula for the given compound is $Cu_2S$

Explanation:

We are given:

Mass of pure compound containing copper and sulfur = 4.963 g

Mass of S = 1.000 g

Mass of Cu = (4.963 - 1.000) g = 3.963 g

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

• Step 1: Converting the given masses into moles.

Moles of Copper =$\frac{\text{Given mass of Copper}}{\text{Molar mass of Copper}}=\frac{3.963g}{63.55g/mole}=0.0624moles$

Moles of Sulfur = $\frac{\text{Given mass of Sulfur}}{\text{Molar mass of Sulfur}}=\frac{1.000g}{32g/mole}=0.0312moles$

• 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 0.0312 moles.

For Copper = $\frac{0.0624}{0.0312}=2$

For Sulfur = $\frac{0.0312}{0.0312}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of Cu : S = 2 : 1

Hence, the empirical formula for the given compound is $Cu_2S$