HSC Chemistry Question Thread

[cnimm2000]

hey guys,
For this dot point:
P.3.3 Gather and process information from secondary sources to write ionic equations to represent the ionisation of acids
Since citric acid is a triprotic acid are we required to know how to write equations for every ionisation step, or just the first one.

If so, have i dont the ionisation steps correctly for citric acid:
C6H8O7 (aq) + H2O (l)   H3O+ (aq) + C6H7O7- (aq)
C6H7O7- (aq) + H2O (l)   H3O+(aq) + C6H6O72-
C6H6O72- (aq) + H2O (l)  H3O+ (aq) + C6H5O73- (aq)

[MisterNeo]

hey guys,
For this dot point:
P.3.3 Gather and process information from secondary sources to write ionic equations to represent the ionisation of acids
Since citric acid is a triprotic acid are we required to know how to write equations for every ionisation step, or just the first one.

If so, have i dont the ionisation steps correctly for citric acid:
C6H8O7 (aq) + H2O (l)   H3O+ (aq) + C6H7O7- (aq)
C6H7O7- (aq) + H2O (l)   H3O+(aq) + C6H6O72-
C6H6O72- (aq) + H2O (l)  H3O+ (aq) + C6H5O73- (aq)

Hey
In the HSC, we assume polyprotic acids fully ionise when reacting with a base. In the ionisation of the citric acid in water, it may be necessary to write out each protonation because they can ask for you to show why the acid is weak or why it forms a buffer with some chemical.
Your equations look good
I'd only write out each step if it were to ionise in water, otherwise reactions with base/metals we assume all 3 are donated at once.

[cnimm2000]

hey guys,
i just wanted to clarify:
that Element 114, Uuq (ununquadium) is now known as flerovium?
thanks in advance

[RuiAce]

hey guys,
i just wanted to clarify:
that Element 114, Uuq (ununquadium) is now known as flerovium?
thanks in advance

Yeah. That's been the case for a while.

113, 115, 117 and 118 are the new ones

[SpanishPear]

Are Back Titration calculations assessable in the HSC Exam?

[kiwiberry]

Are Back Titration calculations assessable in the HSC Exam?

Yes!! There was one in the 2016 HSC I believe

[arii]

I'm not sure how to do this question. Refer to attachment 

[MisterNeo]

I'm not sure how to do this question. Refer to attachment 

[hilaryl]

Hi, i have an upcoming Chemistry skills exam on Monday and I'm not quite sure on how to study it. What should I do to prepare and what will I be expecting? thankyou

[LaraC]

Hello

Wondering if someone could help me with the balanced neutralisation reaction for nitric acid + ammonia solution? Will it have H2O in the products or not? I'm a little confused how to balance it with this....
Thanks.

[RuiAce]

Hello

Wondering if someone could help me with the balanced neutralisation reaction for nitric acid + ammonia solution? Will it have H2O in the products or not? I'm a little confused how to balance it with this....
Thanks.

In general, water doesn't always appear when ammonia is the base involved.

(Edit: Broken code)

[LaraC]

Awesome! Thanks

[Mate2425]

Hi i was just wondering would the following equilibrium's satisfy the solubility of CO2 in water.

Equ. 1   CO2 (g) = CO2 (aq)
Equ. 2     CO2 (aq) + H2O (L) = H^+ (aq) + HCO3^- (aq)
Equ. 3 HCO3^-1 (aq) + H20 (L) = H3O^+ (aq) + CO3 ^-2 (aq)

Where '=' is equilibrium.
Thank you very much 

[3.14159265359]

Heyy can someone please check if I did this correctly. Tyy

[kiwiberry]

Hi i was just wondering would the following equilibrium's satisfy the solubility of CO2 in water.

Equ. 1   CO2 (g) = CO2 (aq)
Equ. 2     CO2 (aq) + H2O (L) = H^+ (aq) + HCO3^- (aq)
Equ. 3 HCO3^-1 (aq) + H20 (L) = H3O^+ (aq) + CO3 ^-2 (aq)

Where '=' is equilibrium.
Thank you very much 

Yep

Heyy can someone please check if I did this correctly. Tyy

The image isn’t appearing for me!!