​​The allowed  threshold limit for the poisonous gas H₂S  is  10mg/ ^m3  . What  pressure does  this correspond  to at 20⁰C assuming H₂S as an ideal gas? What is the volume  of H₂S required  at 600⁰C & 1atm pressure to carry out the sulpuidation of 2.54 g copper to Cu₂S?

Dear student
Please find the solution to the asked query:

The threshold limit for the gas H₂S = 10mg/m³
                                                        = 0.010g/m³
The factor n/V for the gas is given by:

$$\begin{gathered} = \frac{{\displaystyle \frac{0.010g/m^3}{34.08g/mol}}}{1000L/m^3} \\ = 2.9\times {10}^{-7}mol/L \end{gathered}$$
Substituting this value in the Ideal gas equation we get:

P =$\frac{n}{V}RT$
   = 2.9 x 10^-7 x 0.082 x (273+20)  [Here R= 0.082L atm/K mol ]
 = 7 x 10^-6 atm

​Again, the reaction involving the precipitation of Cu2S is :
H₂S +Cu $\to$   Cu₂S + H₂
No.of moles of Cu = $\frac{2.54g}{63.54g/mol}$
                            = 0.0399 mol H₂S

​Volume of H₂S present , V= $\frac{nRT}{P}$
                                         = $\frac{0.0399\times 0.0820\times 873}{1}$
                                         = 2.86L

[Here R= 0.082L atm/K mol and T = 600+ 273 =873K]


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