haber procces (1 Viewer)

[za]

how does the buid-up of unreactive gases,such as argon and methane, lower the efficiency of the conversion?



doesnt having more gases in there increase the pressure, and therefor th e equilibrium would favour a greater production of ammonia coz it has less moles?

 

[CM_Tutor]

Yes, and no.

That is, yes it increases the pressure, but no, this has no effect on the position of equilibrium. A change in pressure only causes a change in the equilibrium position if it is caused by a change in volume, which is not the case here, and so there is no effect.

 

[za]

but doesnt an increase in the concentration of gases correspond to a decrease in volume?

 

[TheKing]

pressure is constant in the haber process?
the concentration of gases can differ but doesn't the pressure remain the same?

 

[CM_Tutor]

Originally posted by za
but doesnt an increase in the concentration of gases correspond to a decrease in volume?

It is true to say that a decrease in volume will cause an increase in the concentrations of all species, but this is not the only change that can result in concentration changes.

 

[CM_Tutor]

Originally posted by TheKing
pressure is constant in the haber process?
the concentration of gases can differ but doesn't the pressure remain the same?

No, the pressure is not constant in the Haber Process. The pressure will decrease as the system moves to the right, favouring ammonia production. Under industrial conditions, the pressure will be kept approximately constant by adding more reactants and liquifying and removing the ammonia product.

 

[xiao1985]

cm tutor: i understand that the build up of unreactive gas such as argo adn methane do not effect the equlibirum position, but , in practice, wont'they reduce the count of successive collisions between the hydrogen and nitrogen molecules??? hence decrease the efficiency???

 

[CM_Tutor]

Sorry, yes, I meant by "there is no effect" that there is no effect on the position of equilibrium. The useless collisions, coupled with the decreaed moles of reactive species, will certainly decrease the efficiency (in the sense of decreaing the yield per unit time), which is why it is of concern to industry. Note that, as impurities go, Ar and CH₄ and much less problematic impurities than CO or S containing species, or worse still O₂