HSC Chemistry Question Thread

[Natasha.97]

Hi,

Can you please explain to me what validity is again? I'm trying to answer a past HSC paper question and its asking me to discuss the validity of a student's investigation.

Thank you!!!

Hi!

Validity is making sure that results obtained stem from ONLY the change in the independent variable (the one you vary), and that the experiment is testing out its hypothesis. This is ensured by keeping all variables constant (except for the independent).

Hope this helps

[Aussie1Italia2]

What about reliability? Just so I don't end up accidentally talking about that.

Thank you!!!

[Natasha.97]

What about reliability? Just so I don't end up accidentally talking about that.

Thank you!!!

Reliability is referring to how consistent your results are, e.g. if another person does the experiment, do the results that they obtain coincide with the results that you have obtained (how similar they are to each other). If they are similar, then the results are reliable, and if not, they are unreliable.

Hope this helps

[winstondarmawan]

Hello!
Are we required to know the diagrams of various batteries for the Batteries dotpoint? (e.g. dry cell, silver button cell)

[Natasha.97]

Hi,

I haven't seen any past papers that require you to draw it, but the dot-point says "gather and present information on the structure", so I'd memorise it just in case!

Hope this helps

[jakesilove]

Hello!
Are we required to know the diagrams of various batteries for the Batteries dotpoint? (e.g. dry cell, silver button cell)

Yeah, I personally did end up learning the structure of my batteries, just because it was then easy to point to the anode/cathode/salt bridge. I don't THINK they could directly ask you to draw them out, but they would definitely help you get full marks in a longer response answer!

[winstondarmawan]

Hello!
For the following question:
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/21439693_1318782871580566_2013104977_o.png?oh=8b19e7a2fb5932c0d979dc8b1f7a8adc&oe=59B2134C
Would we be required to talk about conditions in Haber Process that are not shown in the graph (e.g. 3:1 H2:N2 ratio)? Or do we just focus on temperature and pressure?
EDIT: Shipwrecks
Do sacrificial anodes donate their electrons to the metal that is to be protected? Or do they just corrode preferentially to the protected metal? Or both?
TIA.

[Natasha.97]

Hi,

For this particular question, I'd only refer to temperature and pressure, explaining each line in detail

Hope this helps

[winstondarmawan]

Would appreciate help with the following, TIA.
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/21534556_816544521861838_437814374_o.jpg?oh=a6d0cea1ffd670dc4ed57713635bc9b0&oe=59B4FD34

[hansolo9]

Hello

Is it correct to call ammonia a catalyst in the Solvay process?
Some sources say yes, some say no.

My understanding is that it gets used up to form NH4Cl and they change it back later.

[anotherworld2b]

I was wondering what the monomer structure of Polylactide biopolymer would look like. Could someone help?

[MisterNeo]

I was wondering what the monomer structure of Polylactide biopolymer would look like. Could someone help?

Something like this?

[hazzaizmine]

so for the 2016 mcq 11, when naming wouldn't you start alphabetically, so you would consider bromine as 1, i'm confused because i put the answer as A but in the answers its D. ( this the naming of alkanes q)

[Bubbly_bluey]

so for the 2016 mcq 11, when naming wouldn't you start alphabetically, so you would consider bromine as 1, i'm confused because i put the answer as A but in the answers its D. ( this the naming of alkanes q)

Yes thats what I thought at first. But remember that there is another rule where you have to pick which one would produce least number when you addthem together.
This means that for instance option A: you have 1+1+2+2+2= 8
But for option D: 1+1+1+2+2= 7
so hence why the answer is D. So this is just another that you need for consider on top of alphabetical order.

[Bubbly_bluey]

Regarding to picking equations for electrolytic cells, I thought that if a solution was aqueous, you would have to consider water in a redox reaction. So in this question I thought that water would oxidise instead of the chromate because it is more easier to oxidise. Obviously my answer wasn'tin the option, but just wondering why this is the case.
Thank you