Chem MC help (1 Viewer)

[deswa1]

Hey guys,

I'm probs just being a retard but I don't know why I got this wrong:

Sulfuric acid is diprotic and we assume full ionisation in the core I'm pretty sure so doesn't that mean the H+ concentrations and pH will be the same?

 

[someth1ng]

I think A is the correct answer. I'm quite sure you only assume full ionisation during calculations.

 

[deswa1]

Yeah A is the answer. Oh ok- that makes sense. Say though if it was a three marker to compare the relative pH's of the two, do I assume full ionisation?

 

[someth1ng]

Yeah A is the answer. Oh ok- that makes sense. Say though if it was a three marker to compare the relative pH's of the two, do I assume full ionisation?

No, you only assume full ionisation if it actually asks you to calculate the pH. Otherwise, you assume the second dissociation is only weak. Just out of curiosity, which paper is this from?

 

[deswa1]

No, you only assume full ionisation if it actually asks you to calculate the pH. Otherwise, you assume the second dissociation is only weak. Just out of curiosity, which paper is this from?

CSSA 2011- that's why I thought it was weird because I would have expected more clarity tbh (even something like 'assume the second ionisation is not complete' or whatever)

 

[someth1ng]

Yeah, the H2SO4 business is a bit dodgy. In the HSC, you probably don't even need calculations if that specific question was a 3 marker.