`FeS+2HCl rarr FeCl_2+H_2S`

At RTP;

Room temperature = 23C = 298K

Pressure = 1atm

Using `PV = nRT` for `H_2S` gas;

`1*1 = n*0.08206*298`

   `n = 0.04mol`

So to get 1L of `H_2S` we need 0.4 moles.

Mole ratio

`H_2S:HCl = 1:2`

HCl moles required `= 2*0.4 = 0.8`

So we need 0.8 moles of `HCl` in order to get 1L of `H_2S` gas.

Assumption

• `H_2S` gas act as a ideal gas in RTP conditions
• Room temperature is 23C
• Pressure at room temperature is 1 atm

Hydrogen sulfide gas is produced by reacting iron(II)sulfide with hydrochloric acid. The chemical equation of the reaction is FeS + 2HCl --> FeCl2 + H2S

For each mole of iron(II) sulfide that reacts with 2 moles of HCl one mole of H2S is produced.

At STP 1 mole of an ideal gas occupies 22.4 L. Assuming that the same characteristics are shown by H2S, the number of moles of H2S that occupies 1 L is 1/22.4 = 0.04464. The balanced chemical equation earlier gives that 2 moles of HCl are required for each mole of H2S produced. This gives the number of moles of hydrogen chloride required to produce 1L of H2S at STP equal to 0.08928 moles.