HSC Chemistry Question Thread

[winstondarmawan]

Hello! Does anyone have a Shipwrecks chemical equation cheat sheet they wish to share?

EDIT: Also for experimental design to test the rate of corrosion of iron and steel, would it be more valid to leave the nails in water exposed to air throughout the experiment or initially aerate the water and cap with oil? TIA

Bumping my old post, with a few more questions:
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/20614653_1289240094534844_726534848_n.png?oh=86a5489b0e6e7dcac465cc5aaa54c45d&oe=59853C31
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/20614243_1289243467867840_2102123953_n.png?oh=ab87acd3f18aa0a1375791ff45a8d16f&oe=5984693D
Shipwrecks:
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/20614718_1289249957867191_1685056291_n.png?oh=868cc278b32576eae68aaa1f33fbb489&oe=59852592 Part ii
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/20614288_1289250227867164_1611102850_n.png?oh=4176c79252bc8099ae3879c76d52219b&oe=59846FFE Part ii
TIA!

[Natasha.97]

Bumping my old post, with a few more questions:
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/20614243_1289243467867840_2102123953_n.png?oh=ab87acd3f18aa0a1375791ff45a8d16f&oe=5984693D
TIA!

Here you go

[chelseam]

Hey! Could someone please explain the idea of isomers to me? Even when I try to draw them out if the question gives the formula, I have no idea how to tell if different structures are the same isomer or not! Thank you

[winstondarmawan]

Hey! Could someone please explain the idea of isomers to me? Even when I try to draw them out if the question gives the formula, I have no idea how to tell if different structures are the same isomer or not! Thank you

Count the number of each element in the molecule. If they are the same across 2 molecules, then they are isomers.
Anyways, another question:
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/20622970_1289303244528529_252745868_o.png?oh=2f0014b840d867573ddf2dc7367ce925&oe=59852752
I thought esterifaction resulted in only 2 liquids? I'm confused.

[kiwiberry]

Count the number of each element in the molecule. If they are the same across 2 molecules, then they are isomers.
Anyways, another question:
https://scontent-syd2-1.xx.fbcdn.net/v/t35.0-12/20622970_1289303244528529_252745868_o.png?oh=2f0014b840d867573ddf2dc7367ce925&oe=59852752
I thought esterifaction resulted in only 2 liquids? I'm confused.

Because esterification is an equilibrium reaction, there will be some reactants left over. So ethanol and butanoic acid will be in the reflux mixture too

[winstondarmawan]

Because esterification is an equilibrium reaction, there will be some reactants left over. So ethanol and butanoic acid will be in the reflux mixture too

Thank you! So what would the answer be?

[chelseam]

Count the number of each element in the molecule. If they are the same across 2 molecules, then they are isomers.

Thank you How can you tell if two structures are actually the same isomer or not though?

[kiwiberry]

Thank you! So what would the answer be?

With distillation, the mixture is heated and the component with the lowest bp will evaporate and be collected first, followed by the one with the next highest bp and so on. So the liquids will be collected from lowest to highest bp - ethanol, water, ethyl butanoate, butanoic acid - the ester is 3!

[kiwiberry]

Thank you How can you tell if two structures are actually the same isomer or not though?

If you can give them the same systematic name then they're the same isomer. Like this:
is the same molecule as this: just flipped! They're both 1-chloropropane.
An isomer of this would be 2-chloropropane:
Does that make sense?

[chelseam]

Does that make sense?

Yes!! Thank you so so much!!

[winstondarmawan]

I got an MC question in my trials that was:
What is the conjugate acid of H2SO4?
Can someone please tell me that it is a misprint and meant to be conjugate base? I didn't know H2SO4 could have a conjugate acid...

[Natasha.97]

I got an MC question in my trials that was:
What is the conjugate acid of H2SO4?
Can someone please tell me that it is a misprint and meant to be conjugate base? I didn't know H2SO4 could have a conjugate acid...

Hi! imo it probably is a misprint

[MisterNeo]

I got an MC question in my trials that was:
What is the conjugate acid of H2SO4?
Can someone please tell me that it is a misprint and meant to be conjugate base? I didn't know H2SO4 could have a conjugate acid...

Yeah, it's a misprint.
They either mean conjugate acid of HSO₄^-, or the conjugate base of H₂SO₄.
A strong acid can't act as a base.

[winstondarmawan]

What is the IUPAC name of the following CFC?
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/20624270_1290314487760738_1325675218_n.jpg?oh=1a078c3cce34e549affedbf93cc9e819&oe=5986AAAD

[kiwiberry]

What is the IUPAC name of the following CFC?
https://scontent-syd2-1.xx.fbcdn.net/v/t34.0-12/20624270_1290314487760738_1325675218_n.jpg?oh=1a078c3cce34e549affedbf93cc9e819&oe=5986AAAD

Is that a carbon in the top right?