VCE Chemistry Question Thread

[Yertle the Turtle]

The inert gas addition does not change the pressure or the number of collisions, nor does it react in any way. It does literally nothing in this reaction, and that is one of the things that the textbook goes through, from memory.

[MambaMent..]

The inert gas addition does not change the pressure or the number of collisions, nor does it react in any way. It does literally nothing in this reaction, and that is one of the things that the textbook goes through, from memory.

got ya, thanks. But like why  would my explanation be wrong? wouldn't it make sense for fewer collisions to occur if theres more irrelevant stuff and less relevant stuff present? like for example if hypothetically there were only 5 gas particles present in an empty container, and in another contiainer the same 5 were present but with an extra 2 mol of argon. Wouldn't it be logical to assume there would be a lower reaction rate in the second?

[minhalgill]

when do we use h30+ and when do we use h+?

[Sine]

when do we use h30+ and when do we use h+?

They are pretty much interchangeable in VCE chemistry but it is important to just use what they give you in the question or what you are taking directly from a chemical reaction. If either is 50/50 acceptable I would probably just use H3O+

[minhalgill]

They are pretty much interchangeable in VCE chemistry but it is important to just use what they give you in the question or what you are taking directly from a chemical reaction. If either is 50/50 acceptable I would probably just use H3O+

is there a reason for your preference of h30+?

[sweetiepi]

is there a reason for your preference of h30+?

\(\ce{H3O+}\) is more accepted within the scientific community.

[minhalgill]

what does this mean 'an aqueous solution of a weak acid is more ionised at lower
concentration.'

[rachid.kam]

got ya, thanks. But like why  would my explanation be wrong? wouldn't it make sense for fewer collisions to occur if theres more irrelevant stuff and less relevant stuff present? like for example if hypothetically there were only 5 gas particles present in an empty container, and in another contiainer the same 5 were present but with an extra 2 mol of argon. Wouldn't it be logical to assume there would be a lower reaction rate in the second?

Hey there,
From what I learnt in yr 12 last year, adding an inert gas DOES increase the rate of reaction. This is because the TOTAL pressure of the system increases with the addition of, for example, 2 mols of Argon. Reacting molecules are subsequently forced closer together, increasing the probability of successful collisions, leading to a faster reaction rate. This gas however does NOT change the individual concentrations of the products or reactants, and so will not affect the position of Equilibrium or the Kc value.
Hope that makes sense. Somebody call me out on any BS I may have said. Haven't done this stuff since last year.

[minhalgill]

is Ka in our current study design?

[MambaMent..]

is Ka in our current study design?

nah it was taken out for our current study design (2017 onwards)

[smamsmo22]

Hi, just wondering if anyone had any good notes/resources/tips about errors and titrations? (Or even just minimising errors/ ways to maximise validity/reliability/accuracy/precision generally). I understand what these terms mean and am familiar with standard experimental design questions but I sometimes find it hard to give specific examples and explanations in regards to titrations and other more complicated experiments. Idk if this makes sense but if anyone has any tips or resources related to understanding all the experimental design stuff that'd be super useful.
Thanks!!

[Syndicate]

Hello, just wondering for the exam do we need to know about how different fuels are sourced in Australia, energy transformations in gas-fired power plants, and the pros and cons of lithium batteries etc? I see it in company exams a lot, but I was told that VCAA doesn't usually test you on these stuff?

Also, I go to Suzanne Cory High School, which being a selective school has a pretty strong chem cohort, however I'm not actually that good and currently ranked just above average (got a ~60% on the 2018 TSSM trial exam). Is a 35+ study score possible?

Thanks in advance.

Other than the source of fuels, I believe the other two points can be easily tested in the exam. I think there was an energy transformation question in one of the VCAA exams (not entirely sure, so I can be wrong).

35+ is high likely if you do well on the exam. I had an average ranking but in the exam I think I only lost about 4-5 marks, and got a 40+ study score.

[TheAspiringDoc]

Is the electrolyte the electrically conductive solution that contains the conjugate pair of the electrode(s)? In a galvanic cell is it the salt bridge or the solution surrounding the electrodes?

Thanks

[MambaMent..]

Is the electrolyte the electrically conductive solution that contains the conjugate pair of the electrode(s)? In a galvanic cell is it the salt bridge or the solution surrounding the electrodes?

Thanks

the electrolyte is the electrocondutive solution that contains the ions either involved in the the redox reactions or ions that are involved in maintaining electrical neutrality. idk what you mean by conjugate pair of electrodes though.

In a galv cell it is the solution surrounding the electrodes- the salt bridge Is immersed within this solution in both half cells which allows for the entry of cations/anions into the cells that balance any charges created (which is necessary in maintaining the operation of the cell)

[minhalgill]

1)why does only temperature affect Kc why doesnt pressure etc?


2)also, in the attacthed question 6 , how can the pH be less than 7 and the concentration of h30+ and OH- still be equal? what does 'pure' water exactly mean? and how would the self ionisation of water being endothermic, lower the pH to 6.14? wouldnt it stay at 7?

3)also in the marking scheme it says ' Students should also be aware that an aqueous solution of a weak acid is more ionised at lower
concentration.' What exaclty does this mean?

4) i was sure i was able to distinguish between the following types of bonding, but after doing a couple questions and getting my answers wrong, im somewhat confused between the differences between the following types of bonding, and how we know this type of bonding exists?( could anyone please help me with this, ive tried searching google, but im even more confused now)
-Dispersion
-Hydrogen
-Dipole-dipole

5) in part (c)  why does the marking scheme say 'partially' oppose the change. do we have to say partially? will this be the case for all other changes such as temp, volume etc? do we have to make a refernce to le chatliers principle?

6) also, when it says proton does it mean H+

7) for Question 7 (a), i dont understnad how we get water on the reactants side, as it isnt mentioned anywher in the question?