Pressure & Rate of reaction (1 Viewer)

[QZP]

How come I never see sample answers talking about increasing pressure to increase rate of reaction (assuming gaseous reaction) as opposed to temperature? Like in the Haber process with questions involving "balance", temperature is a balance between yield and rate of reaction; so why not say similarly for pressure it is a balance?

 

[Kurosaki]

Personally I've always talked pressure.

 

[enigma_1]

How come I never see sample answers talking about increasing pressure to increase rate of reaction (assuming gaseous reaction) as opposed to temperature? Like in the Haber process with questions involving "balance", temperature is a balance between yield and rate of reaction; so why not say similarly for pressure it is a balance?

Yeah pressure also requires balancing. You would need to talk about both temperature and pressure I reckon unless it specifies :/ High pressure increases the number of favourable collisions and so increases the rate of reaction by LCP shifts forward blah blah. If pressure is too high then it can cause safety problems eg a catastrophic explosion could occur, but if pressure is too low then the particles would not collide as frequently (according to the collision theory) and less collisions would occur thus slowing the rate of reaction so a compromise of 25MPa is needed.

 

[QZP]

Personally I've always talked pressure.

You've talked about it with respect to reaction rate and not just LCP? O: I don't know anyone who does

 

[QZP]

Yeah pressure also requires balancing. You would need to talk about both temperature and pressure I reckon unless it specifies :/ High pressure increases the number of favourable collisions and so increases the rate of reaction by LCP shifts forward blah blah. If pressure is too high then it can cause safety problems eg a catastrophic explosion could occur, but if pressure is too low then the particles would not collide as frequently (according to the collision theory) and less collisions would occur thus slowing the rate of reaction so a compromise of 25MPa is needed.

My balance for pressure has always been (yield vs. safety/cost) with no mention of rate of reaction but I guess I'll include it now

 

[Cleverusername5321]

You should always try to talk about pressure. But be careful, pressure only applies if it's a closed system (container).

 

[faisalabdul16]

Increasing the pressure, provides more kinetic energy for successful collisions to occur between particles thus increasing the rate of reaction.

 

[SuchSmallHands]

Increasing the pressure, provides more kinetic energy for successful collisions to occur between particles thus increasing the rate of reaction.

No, that's temperature (I know we're done now, but some kids might read this later). Pressure is a factor only in reactions involving gases. Increasing pressure doesn't introduce more energy to the system. Rather, what happens is that the system shifts to reduce pressure by moving toward the side with the fewest moles of gas. In the Haber process there's 4 moles of gas on the left and 2 on the right. The reason that increasing pressure favours the formation of products is because the system moves toward making 2 moles of NH3 rather than 4 moles of N2 and H2 in order to relieve the additional pressure.