general questions, heeellppp please. (1 Viewer)

[paper cup]

These are spread across the modules so, I'm going to post them here.


what's a deuteron?
-----
Fe2+/Fe3+/Pt//Zn2+/Zn
How does this work?
----
Do we need to know the ranges of indicators, dot point only says identify, and are there 'must know' ion spray tests?
-----

This question, Q28 of the 2002 paper.
One of the reactions used to form sulfuric acid is the reaction of oxygen with sulfur dioxide under equilibrium conditions to form sulfur trioxide. Pre reaction the concentration of SO2 was 0.06, conc of O2 was 0.05, after equilibrium was reached, the conc of SO3 was 0.04

Letting the conc of SO3 be x,

Using ICE we have
SO2 O2 SO3
I 0.06 0.05
C 0.04 0.03
E 0.06 - x = 0.02, 0.05 - 0.5x = 0.03, 0.04

The initial concentration of the SO3 should be 0 but the answers give it at 0.04. Typo? Why does the is there no difference between the equilibrium and intial concentrations of SO3? I know you don't need to know it to calculate K but I'd like to know why.

-----

OK so sulfuric acid is a strong acid, meaning that it ionises close to 100%. Buuttt, in one of the answers, 2002 paper Q 28 c i) The success one answers refer to it 'ionising strongly but incompletely' what does this mean.
How come sulfuric acid ionises incompletely?
---

And is there any here with the pracs for industrial chem? I need help with saponification observations - we didn't do the prac. And the Solvay modelling one as well.

--> observations with saponification - what happens after the oil is added, after the container is shaken for one minute and the layers were allowed to settle; after being shaken for a further 5 minutes and the layers allowed to settle?

Thanks, and big e-mwah from cherry to anyone who answers

 

[Dreamerish*~]

Some of these things look quite unfamiliar to me.

Can you separate the core questions from the options questions?

 

[sikeveo]

ill let ppl post, i have some info on the saponification pracs. I'll dig them out tomorrow.

 

[paper cup]

Some of these things look quite unfamiliar to me.

Can you separate the core questions from the options questions?

oh good if they look unfamiliar to you, that's a very good sign but it's probably cos they are industrial chem option qs

These are spread across the modules so, I'm going to post them here.


POM I think
what's a deuteron?
-----
POM

Fe2+/Fe3+/Pt//Zn2+/Zn
How does this work?
----

ACIDIC

Do we need to know the ranges of indicators, dot point only says identify, and are there 'must know' ion spray tests?
-----


INDUSTRIAL
This question, Q28 of the 2002 paper.
One of the reactions used to form sulfuric acid is the reaction of oxygen with sulfur dioxide under equilibrium conditions to form sulfur trioxide. Pre reaction the concentration of SO2 was 0.06, conc of O2 was 0.05, after equilibrium was reached, the conc of SO3 was 0.04

Letting the conc of SO3 be x,

Using ICE we have
SO2 O2 SO3
I 0.06 0.05
C 0.04 0.03
E 0.06 - x = 0.02, 0.05 - 0.5x = 0.03, 0.04

The initial concentration of the SO3 should be 0 but the answers give it at 0.04. Typo? Why does the is there no difference between the equilibrium and intial concentrations of SO3? I know you don't need to know it to calculate K but I'd like to know why.

-----

This could be Acidic or Industrial

OK so sulfuric acid is a strong acid, meaning that it ionises close to 100%. Buuttt, in one of the answers, 2002 paper Q 28 c i) The success one answers refer to it 'ionising strongly but incompletely' what does this mean.
How come sulfuric acid ionises incompletely?
---

INDUSTRIAL

And is there any here with the pracs for industrial chem? I need help with saponification observations - we didn't do the prac. And the Solvay modelling one as well.

--> observations with saponification - what happens after the oil is added, after the container is shaken for one minute and the layers were allowed to settle; after being shaken for a further 5 minutes and the layers allowed to settle?

sikeveo please do, I really need help with them and my teacher has gone on holiday, meaning the many emails I have sent will not be read until next week by which time she will be occupied with chem class of 2006 :/

 

[sikeveo]

Hey for the observation with saponification, you can do it yourself. Its easy.

ACIDIC

Do we need to know the ranges of indicators, dot point only says identify, and are there 'must know' ion spray tests?

Yes I have seen it in past exams. However they usually give you the data. Just know a few to be safe.

 

[paper cup]

Hey for the observation with saponification, you can do it yourself. Its easy.

ACIDIC

Do we need to know the ranges of indicators, dot point only says identify, and are there 'must know' ion spray tests?

Yes I have seen it in past exams. However they usually give you the data. Just know a few to be safe.

not at home I can't.

 

[sikeveo]

Look at hsc online.

 

[paper cup]

Look at hsc online.

...do you have the observations?

 

[Dreamerish*~]

Deuteron: Discovered in 1932 by Harold C. Urey, deuterium is a stable isotope of the element hydrogen. An atom of deuterium consists of one proton, one neutron and one electron. About .015% of natural hydrogen is composed of deuterium.

Sure sounds a bit out-of-the-syllabus.

Iron-zinc cell: Fe2+/Fe3+/Pt//Zn2+/Zn
Well, according to the table of standard reduction potentials, zinc is the anode and iron is the cathode.

The half equations are:

Zn_(s) → Zn²⁺ + 2e^- ... 0.76 V

Fe³⁺ + e^- → Fe²⁺ ... 0.77 V

So the E⁰ of this cell is 0.76 + 0.77 = 1.53 V

The platinum wire is there (I'm assuming) as the inert cathode, allowing the reduction of Fe³⁺, which is aqueous, not a solid.

Ranges of indicators: They're usually given. Know the approximate. Never heard of an ion spray tests. Do you mean flame tests?

Sulfuric acid: It is a strong acid. By definition, strong acids ionise almost to completion. So close to completion that often they are said to ionise to completion. I don't know why Success One said it ionises incompletely. Nothing ionises completely - strong acids ionise around, oh I don't know, 99.9%?

 

[MedNez]

This question, Q28 of the 2002 paper.
One of the reactions used to form sulfuric acid is the reaction of oxygen with sulfur dioxide under equilibrium conditions to form sulfur trioxide. Pre reaction the concentration of SO2 was 0.06, conc of O2 was 0.05, after equilibrium was reached, the conc of SO3 was 0.04

Letting the conc of SO3 be x,

Using ICE we have
SO2 O2 SO3
I 0.06 0.05
C 0.04 0.03
E 0.06 - x = 0.02, 0.05 - 0.5x = 0.03, 0.04

The initial concentration of the SO3 should be 0 but the answers give it at 0.04. Typo? Why does the is there no difference between the equilibrium and intial concentrations of SO3? I know you don't need to know it to calculate K but I'd like to know why.

Noooo

2SO2 + O2 -> 2SO3
I 0.06 0.05 0
C 0.04 0.02 0.04
E 0.02 0.03 0.04

You know that there's 0.04 SO3 at end. Therefore change is 0.04. But look at the mole ratio, it's 2:1:2, so the change for O2 is only 0.02. Add up the first of the table.

I believe the answers are wrong. There is 0 initially. I'm with you on this, and I did the other day, so I guess it's a typo.

Med

 

[kitty_purrswell]

Ok, I'll do what I think I can

* A deuteron is is the nucleus of a deuterium atom consisting of one proton and one neutron. (If you're wondering, deuterium is one of the stable isotopes of Hydrogen).

*The equation in the next question is that of a Redox reaction. You need to identify what is being oxidised and reduced in the reaction. (In this case, the Fe loses an electron to become OXIDISED, whereas the Zn 2+ is REDUCED to become Zn.) The Pt acts as a spectator ion, and is not involved in the final products, hence, u can leave it out of your redox equation. In a HSC question, u may also be asked 2 draw a diagram of this circuit.

*Pretty sure we don't need to know the ranges of indicators, but u might want 2 learn a few for your titration experiments. We used Phenolphthalein which has a pH range of 8.2 - 10.0. Just remember that indicators themselves DON'T change the pH, they purely act as INDICATORS of what's already there .

*Not sure about the next one, haven't come across the ICE things before.

*Industrial chemistry wasn't my elective so a no no on that one as well

*The ionisation question is best explained from the hsc.csu.edu.au site: Read it below:

The ionisation of sulfuric acid is exothermic, releasing lots of heat.
H2SO4(aq) H+(aq) + HSO4–(aq) + heat

Sulfuric acid dissociates in two steps.
Notice that sulfuric acid is a strong acid in its first dissociation, but the HSO4– ion is a weak acid and only dissociates slightly.

H2SO4(aq) H+(aq) + H SO4–(aq) K is very large

HSO4– (aq) H+(aq) + SO42–(aq) K= 1.2 x 10-2

Hope that helps

 

[paper cup]

Noooo

2SO2 + O2 -> 2SO3
I 0.06 0.05 0
C 0.04 0.02 0.04
E 0.02 0.03 0.04

You know that there's 0.04 SO3 at end. Therefore change is 0.04. But look at the mole ratio, it's 2:1:2, so the change for O2 is only 0.02. Add up the first of the table.

I believe the answers are wrong. There is 0 initially. I'm with you on this, and I did the other day, so I guess it's a typo.

Med

thanks. so the equations are just a load of crap? because I'd never seen them before. :/ maybe it's just cos I'm stupid

 

[mitochondria]

Sulfuric acid: It is a strong acid. By definition, strong acids ionise almost to completion. So close to completion that often they are said to ionise to completion. I don't know why Success One said it ionises incompletely. Nothing ionises completely - strong acids ionise around, oh I don't know, 99.9%?

Dreamy That's because the pK_a of the second ionisation is 1.99 not uber negative infinity (like the first one) ^^

 

[Dreamerish*~]

Dreamy That's because the pK_a of the second ionisation is 1.99 not uber negative infinitive (like the first one) ^^

Oh... yeah!

I get it. Thanks Mito, you massive, massive chemistry nerd.

 

[paper cup]

Dreamy That's because the pK_a of the second ionisation is 1.99 not uber negative infinity (like the first one) ^^

he's a very very good dude this one if you come back to the thread can you tell me if the ICE equations are a load of crap like MedNez implies? chem is like the subject I am going to boommmmbb in :/

 

[mitochondria]

Oh... yeah!

I get it. Thanks Mito, you massive, massive chemistry nerd.

Did I hear sarcasm or was it just me? *scratch head* (Or was it a complement? )

I'm 99.9% sure that I knew less chemistry than you do when I was doing what you are doing now (besides, you know how bad I did in the HSC for chem)

he's a very very good dude this one if you come back to the thread can you tell me if the ICE equations are a load of crap like MedNez implies? chem is like the subject I am going to boommmmbb in :/

*blush*

ICE equations are not a load of cr*p (although I just found out that they are called ICE equations just then ). My point is, we still use that a lot to solve more complicated problems, so it mustn't be a load of cr*p unless the uni is teaching me a load of cr*p (some may agree with that )

 

[sikeveo]

ICE ? Drugs? Hey Mito I'll be seeing you next yr!!

 

[mitochondria]

ICE ? Drugs? Hey Mito I'll be seeing you next yr!!

Oh goodie ^^

If you ever do Chem or Advanced Science you'll definitely bump into me

 

[paper cup]

Did I hear sarcasm or was it just me? *scratch head* (Or was it a complement? )

I'm 99.9% sure that I knew less chemistry than you do when I was doing what you are doing now (besides, you know how bad I did in the HSC for chem)

the ones in the question I mean

lol isn't it a neat thingamajig, ICE. how badly did you go? (is your definition of badly like xiao's, i.e. 95/100 OMG NO I DIDN'T GET 100 THE WORLD IS GOING TO FALL DOWN)

*blush*

ICE equations are not a load of cr*p (although I just found out that they are called ICE equations just then ). My point is, we still use that a lot to solve more complicated problems, so it mustn't be a load of cr*p unless the uni is teaching me a load of cr*p (some may agree with that )

I meant for the question I posted.
Yeah I like that ICE thingamajiggy short remembering thing. how badly did you go, badly as in 95/100 OMG I DIDN'T GET 100 THE WORLD IS GOING TO END?

 

[mitochondria]

I meant for the question I posted.
Yeah I like that ICE thingamajiggy short remembering thing. how badly did you go, badly as in 95/100 OMG I DIDN'T GET 100 THE WORLD IS GOING TO END?

No, the question was not stupid at all

*ahem*

*thinks for a moment*

Well, if it makes you feel any better, I didn't even get into band 6 '-___-