Hydrogen fluoride is used in the manufacture of freons (which destroy ozone in the stratosphere) and in the production of aluminum metal. it is prepared by the reaction caf2 + h2so4 → caso4 + 2hf in one process, 6.25 kg of caf2 is treated with an excess of h2so4 and yields 2.35 kg of hf. calculate the percent yield of hf. % yield

The percentage yield of HF is 73.36 %

Explanation:

To calculate the number of moles, we use the equation:

    ....(1)  

For calcium fluoride:

Given mass of calcium fluoride = 6.25 kg  = 6250 g   (Conversion factor: 1 kg = 1000 g)

Molar mass of calcium fluoride = 78.07 g/mol

Putting values in above equation, we get:  

For the given chemical reaction:

By Stoichiometry of the reaction:

1 mole of calcium fluoride produces 2 moles of hydrofluoric acid

So, 80.05 moles of calcium fluoride will produce = of hydrofluoric acid

Now, calculating the theoretical yield of hydrofluoric acid using equation 1, we get:

Moles of of hydrofluoric acid = 160.1 moles

Molar mass of hydrofluoric acid = 20.01 g/mol

Putting values in equation 1, we get:

To calculate the percentage yield of hydrofluoric acid, we use the equation:

Experimental yield of hydrofluoric acid = 2.35 kg

Theoretical yield of hydrofluoric acid = 3.20 kg

Putting values in above equation, we get:

Hence, the percentage yield of HF is 73.36 %