Question

How many liters of F2 at STP are needed with 4.00L of H2 also measured at STP in
following reaction:
H2 (g) + F2 (g) 2HF(g)

Answer 1

The answer is in the picture

Answer 2

Answer: 4 liters of $F_2$ are needed for the following reaction.

Explanation: For the given reaction:

$H_2(g)+F_2(g)\rightarrow 2HF(g)$

At STP:

22.4 L of gas is occupied by 1 mole of gas.

By Stoichiometry,

1 mole of $N_2$ require 1 mole of $F_2$ to produce 2 moles of HF.

Hence, it will require 22.4L of $H_2$ to react with 22.4L of $F_2$ to produce 44.8L of HF.

So, 4 L of $H_2$ will require = $\frac{22.4\times 4}{22.4}=4L$

Hence, 4 liters of $F_2$ will be needed with 4 L of $H_2$ for the following reaction.