For the ethenylbenzene one I put ethylbenzene considering that is what is referred to in the conquering chemistry textbook and macquarie/ dot point book. I know wikipedia isn't very accurate but it gives this same definition for the monomers ethylbenzene and ethenylbenzene "This aromatic hydrocarbon is important in the petrochemical industry as an intermediate in the production of styrene" - is this something the news was referring to about the multitude of errors found in this years chem paper?
Also for the sulfuric acid one I think it has to be H2SO4 because it is a strong diprotic acid whereas citruc acid, although triprotic only partially ionises therefore making it weaker than H2SO4 as all its 'diproticness' will ionize.
For Q6, D) Ethenylbenzene is correct. You should never completely trust HSC textbooks. (Btw, 'ethyl' would be when there's no double bond.)
It's not outside the scope of the syllabus because there is a syllabus point for it.
• identify the following as commercially significant monomers:
- vinyl chloride
by both their systematic
and common names
You seem to be a little confused about weak and strong acids.
Weak acids, when added to water, will partially ionise, whereas strong acids will completely ionise.
However, the situation here is not as simple. We are adding strong base to titrate it.
In this case, strength of acid does not really matter, it is the mole ratio involved in acid-base reaction that matters.
Yes, strong acids will start from a lower pH, but it will also be titrated to end point with less volume than citric because H2SO4 is diprotic whereas C6H8O7 is triprotic.
As more base is added, the hydronium ion concentration decreases and the acid's dissociation equilibrium will shift forward, producing more hydronium ions until citric acid is completely deprotonated - equivalence point (assuming you didn't add excess base) and end point should be approximately equal to equivalence point because that's the whole point of an indicator.
Hope this helps.