Assumption question

[amimery]

people have been saying that the answer was that the conc of the conjugate acid was negligible etc... buttt would another appropriate response for the assumption be that the [H+] = [ch3ch(oh)coo -] ...? thoughts?

[m@tty]

That is an assumption, so I suppose it should be a valid response. Don't know how they'd mark it though. It is a fairly important assumption for the calculation.. It assumes that the H+ from the self-ionisation of water is negligible. I expect there will be a wide variety of accepted answers. So you should be fine.

[Studyinghard]

I said the exact same thing but apparentally its wrong? reason was that this is not an assumption. its a FACT

[Whatlol]

I said the exact same thing but apparentally its wrong? reason was that this is not an assumption. its a FACT

its not a fact...

[bblovee]

that the concentration of the acid at equilibrium was the same as the initial concentration?

[Studyinghard]

I said the exact same thing but apparentally its wrong? reason was that this is not an assumption. its a FACT

its not a fact...

So that assumption is correct? If so then I just went one higher than my estimation

[stonecold]

that the concentration of the acid at equilibrium was the same as the initial concentration?

yeah, this is what i said.  

assumed that [lactic acid] had not changed when in fact it has decreased by a very small amount.

[andy456]

I said the exact same thing but apparentally its wrong? reason was that this is not an assumption. its a FACT

its not a fact...

So that assumption is correct? If so then I just went one higher than my estimation

I dont think that is an assumption. If one molecule of lactic acid dissapates one H+ ion will be formed and one CH3.....- ion will be made..... t

[becca92]

I said the exact same thing but apparentally its wrong? reason was that this is not an assumption. its a FACT

its not a fact...

So that assumption is correct? If so then I just went one higher than my estimation

I dont think that is an assumption. If one molecule of lactic acid dissapates one H+ ion will be formed and one CH3.....- ion will be made..... t

However what if the container is contaminated and there are traces of CH3CH(OH)COO- already inside, hence we are assuming that [H+] is exactly equal to [CH3CH(OH)COO-] after ionisation. Just thinking..

[lisafaustina]

Um I said that the temp is 25 degrees..wrong right

[Studyinghard]

I said the exact same thing but apparentally its wrong? reason was that this is not an assumption. its a FACT

its not a fact...

So that assumption is correct? If so then I just went one higher than my estimation

I dont think that is an assumption. If one molecule of lactic acid dissapates one H+ ion will be formed and one CH3.....- ion will be made..... t

However what if the container is contaminated and there are traces of CH3CH(OH)COO- already inside, hence we are assuming that [H+] is exactly equal to [CH3CH(OH)COO-] after ionisation. Just thinking..

I dont think you're just thinking..you're just ASSUMING.
get it ? i lol'ed

[appianway]

IMO, there are two good correct responses to this question. The first is to assume that there are no traces of lactic acid already in the container (and yes, there could be), and the second is to assume that it's a very weak acid and that [A] does not change even what it deionises. It said write ONE assumption, but the reality is that you would've made more than one assumption. Personally, I wrote the first one, because I actually didn't use the 2nd assumption in a past paper and I still received the same answer to the correct number of significant figures.

[Hazim]

that is a fact, not an assumption theyre in the same mol to mol ratio as theyre produced

[Studyinghard]

that is a fact, not an assumption theyre in the same mol to mol ratio as theyre produced

but really, is anything in this world a fact? its all an illusion.

[Greggler]

vcaa will probs accept a range of answers.
What OP has said should be fine, in fact in my text book it in fact gives  little step by step thing on how to do these question and its exact wording is something like 'we must make the assumption that H+ = acid'