Question

H+ + OH- ----> H2O

I thought since these two react concentrations of both ions go down and kW goes down.

Was wrong

Will post question in a bit.

Answer 1

#351

Answer 2

@Rushwr @Ciarán95

Answer 3

What was the answer is it C?

Answer 4

I took it as C cuz K values only varies with the temperature hence it increases!!! SO the answer is D>??????????

Answer 5

yeah it's D.

Answer 6

The explanation they gave made no sense tome

Answer 7

Okai here u go then
When it is exothermic the heat is given out meaning that the surrounding temperature increases right? And we also know that all K values depend only upon the temperature. Hence when temperature increases the K value also increases

Answer 8

I'll post it.

"The production of water from hydrogen and hydroxide ions, is exothermic; therefore the reverse reaction, production of the ions from water, is endothermic. It is on this endothermic reaction that Kw was based. Heating a reaction favors the endothermic reactions so the concentration of hydrogen and hydroxide ions would increase thereby increasing the value of Kw"

Answer 9

Yeah.. i'm following you there! at first it said it's an exothermic reaction, But the reason why i said increases is because I thought that the concentration of both ions would have to go down to form water, just was not sure at all.

Answer 10

SOo did u get what I said now? @Photon336

Answer 11

so.... wait ... increasing temperature it has to establish a new equilibrium.. so k changes..

Answer 12

yes

Answer 13

\[K _{w} = [H ^{+}][OH-]\]

Kw, the ionic product of water, is like the equilibrium constant for the aboove equilibrium system...we might sometimes refer to it as a reaction which goes to 'completion' in the formation of water, but there will always be a very, very small number of water molecules dissociating in the reverse direction to form the ions once more.

@Rushwr explains it well above....we must not really consider this as a reaction but rather as an equilibrium system, established at a certain temperature and pressure. Le Chatelier's Principle states that if a system is at equilibrium, then any changes we force onto the system will result in the system 'counteracting' these changes once more.

So, if we add more of one of our reactants, the system will counteract to use it up and make/favour more products; if we increase the pressure, it will counteract to reduce the pressure (favouring the side with less no. of molecules more); and if we increase the temperature, the system will counteract by reducing it and favour the formation of species which will 'absorb' this heat best, rather than simply releasing more.

In our case, this results in the reverse reaction being slightly more favourable, and thus a higher concentration of H+ and OH- being present at equilibrium with H2O molecules. This increases our Kw value as a result.

Answer 14

@Photon336 you're correct in saying also that a 'new' equilibrium has formed when we change the conditions. An equilibrium system is essentially a certain fixed mixture of reactants and products forming and reforming in opposite directions. Once we change these proportions/amounts of each species in the mixture, we are proceeding to form a new equilibrium. I like to think of though as the initial system counteracting/counterbalancing the changes we make to it, but there are a number of different ways of phrasing it. Anyway, hope that helped you out!

Answer 15

That was perfectly explained @Ciarán95 thank you!