Q.2.20 P - Chemistry: Molecular Nature Of Matter And Change

Question

Fluorite, a mineral of calcium, is a compound of the metal with fluorine. Analysis shows that a 2.76-g sample of fluorite contains 1.42 g of calcium. Calculate the (a) mass of fluorine in the sample; (b) mass fractions of calcium and fluorine in fluorite; (c) mass percents of calcium and fluorine in fluorite.

Step-by-Step Solution

Answer

1. Mass of fluorine in the fluorite sample = 1.34 g
2. Mass fraction of calcium = 0.515 and of fluorine = 0.485
3. Mass percent of calcium = 51.5% and mass percent of fluorine = 48.5%

 

Step 1: Mass of fluorine in Fluorite

Fluorite is a mineral of Ca and fluorine with the formula CaF₂. As it contains only calcium and fluorine. Hence, the mass of fluorine can be calculated as:

$$\begin{gathered} Mass of Fluorine=Mass of fluorite-Mass of Calcium \\ = 2.76g-1.42g=1.34g \end{gathered}$$ 

 

Step 2: Mass Fractions

The formula for mass fraction: 

  $Mass fraction =\frac{Mass of component}{Total Mass}$

 Mass fraction of calcium and fluorine can be calculated as,

 $Mass fraction of Calcium=\frac{1.42}{2.76}=0.515$

$mass fraction of fluorine=\frac{1.34}{2.76}=0.485$

 

 

Step 3: Mass Percent Calculation

The formula for mass percent is given as

 $Mass percent=\frac{Mass of component}{Total Mass}\times 100$

 The mass percent of calcium and fluorine can be calculated as,

 $mass percent of Calcium=\frac{1.42}{2.76}\times 100=51.5\%$