Question

Hydrogen fluoride, HF, decomposes to produce hydrogen gas and fluorine gas. If 80.0 g of HF were initially placed in a reaction vessel, calculate the amount of HF that was left if equilibrium was reached when 2.0 g of hydrogen had been produced.

Answer 1

Answer : The amount of HF left was, 76.0 grams.

Explanation :

The balanced chemical reaction is:

`2HF\rightleftharpoons H_2+F_2`

Initial amount 80.0g 0g 0g

At eqm. (80.0-2x)g (x)g (x)g

As we are given that:

Amount of
`H_2` at equilibrium = 2.0 g

That means,

x = 2.0 g

Now we have to determine the amount of HF that was left if equilibrium was reached when 2.0 g of hydrogen had been produced.

Amount of HF left = (80.0 - 2x) g

Put x = 2.0, we get:

Amount of HF left = (80.0 - 2\times 2.0) g

Amount of HF left = 76.0 g

Thus, the amount of HF left was, 76.0 grams.