Edexcel A2 Chemistry Unit 4 26/01/12 PM

Can someone quickly explain an alkaline buffer solution to me please?

Buffer solution is above the pH of 7.
Consists of a weak base and its salt.
So, weak bases like Ammonia and a salt that is formed with ammona, like ammonium chloride etc.
They both form a buffer solution.

Sorry if I wasn't clear, but I meant what happens when an acid or alkaline is added

The same principle applies to both an acidic buffer or an alkaline buffer.

When acid is added (so the h+) which lies on the right hand side of the equillibrium, more H+ combines with the other product like NH3 to form NH4+. Also the equillibrium wants to restore itself so it shifts to the left.
When an alkaline is added (so OH), it reacts with the H+, causing it to be removed off the equillbrium as water is formed, so more of, say, NH4+ dissociates to replace the H+.

Therefore the H+ concentration doesnt change so the pH stays constant.

How I remember is inert - total entropy is negative so they just don't react. Like noble gases

Stable is due to a high activation energy - so from the thermo you can see that if you increase temperature then more molecules have kinetic energy greater than EA so it becomes unstable..


That didn't really make much sense :P

If the total entropy is negative then the reactants are thermodynamically stable and then reaction won't take place. But if the total entropy is positive then the reaction is feasible however if the activation energy is very high it's unlikely to go and so you would say the reactants are kinetically inert.

Do we need to know the specifics of the Haber Process, Urea production or that section on catalytic converters?

Do we need to know the specifics of the Haber Process, Urea production or that section on catalytic converters?

are you talking about the HSW box on page 25-6 in the blue Ann Fulick book??

No, according to the specification we don't need to know the detail of industrial processes.

Yep

the no, we don'y

Okay, thanks for that. Also, how much do we have to know about the propanone and iodine reaction as my teacher never went through it

Hi, does anyone know the answer to this please?

yes-you need to learn it.
It isnt soely remembering but you would have to understand what is going on. As in how they are using this reaction to figure out the rate of reaction.

Okay, so I know how they calculate rate and order through quenching the reaction and titration with sodium thiosulfate, but do we have to know the actual mechanism used to form iodopropanone?

if you mean the reaction, then yes most likely.

Yes you need to know Iodoform reaction