Question

The catalyst for the reaction is concentrated phosphoric acid (a liquid) supported on solid silica. State the effect of the catalyst on

a) the rate of formation of the ethanol

b) the percentage of the ethene converted into ethanol

Answer 1

@nincompoop

Answer 2

catalysts affect the rate of a reaction, but not the overall equilibrium concentrations of the reactant and product.

so a) it speeds up the rate, b) no effect

Answer 3

yay I was right :D

Answer 4

okay and one more thing.

The temperature actually used is 300C (not particularly low). Explain why really low temperatures aren't used in practice.

Answer 5

@aaronq

Answer 6

it's to maintain the kinetic energy of the system high (for effective collisions), but i think also to keep the substrate in the the gas phase, which increases the surface area and thus the rate of the reaction.

Answer 7

oh that makes sense because the reactants have to be in a gaseous phase and they need energy...thanks @aaronq !

Answer 8

no problem !

Answer 9

okay supposed you have reaction \(A+B\rightleftharpoons C\)

using le chateliers principles we can affect the equilibrium concentrations
1. remove A or B, eq shifts left
2. add more C, eq shifts left
3.for a reaction involving gases: increase the volume or decrease the pressure
4. depending whether exo- or endothermic, change the temperature

Answer 10

alright this is the last time I'll bug you :)

How could I increase the production of ethanol besides heat and pressure:\[CH_2=CH_2(g)~+~H_2O(g)\rightleftharpoons CH_3CH_2OH~~~~~~~~~~~~\Delta H=-46~ kJ~mol^{-1} \]

Answer 11

i could remove some of the ethanol, right? but idk why that doesn't seem like the best answer

Answer 12

you can add xss reactants (ethyne or water), or remove the ethanol as it's wing produced

Answer 13

being*

Answer 14

oh true, i could add reactants

Answer 15

yeah, that's how it's often done in industry. the product is removed to drive the equilibrium forward.

Answer 16

cool, thank you so so much @aaronq, honestly a lifesaver!

Answer 17

no problem at all, really !