**Chemistry...Before/After

FaoiSin

Don't know why people even bother with predictions for English. It's 50 marks and even if the poet you know does come up the question might be awkward.

Random_Person

Exactly and with chemistry you can predict all you want but the people with the good grades are going to be those who understand all aspects of the course and can apply their knowledge to different questions thrown at them, not just the standard stuff seen most years.

Darksider

Experiment predictions:

Q1. Either Winkler method(more likely since its the more difficult of the two and its been longer since it was up) or Hydrated sodium carbonate titration.
Q2. Ethanoic acid preparation.
Q3. Relative molecular mass of a volatile liquid.

Other predictions: There's most likely going to be a full Section B question on Rates of Reactions.

aislingmajella

if i knew all the experiments, the q5 stuff, equilibrium, rates of reactions, pH, acids and bases, oxidation and reduction am i covered ta get a c grade???

Mista

aislingmajella wrote: »

if i knew all the experiments, the q5 stuff, equilibrium, rates of reactions, pH, acids and bases, oxidation and reduction am i covered ta get a c grade???

Do organic.

ashalingable

Really really hate electrochemistry with a passion ........ Do you think I'll be ok leaving it out???

Duffman K

when doing titration questions with : Vo x Mo/no = Vr x Mred/nr

I never know how to tell which is the oxidising agent and whic is the reducing agent ,

For example : na2co3 + 2hcl => 2nacl + co2 +h2o

Vo= Vr=
Mo = Mred =
no = nr =

any help would be appreciated.

screeeewed

Do we need to know the exact equations for le chateliers principle..? And do we need to know all three..or just one way to investigate it?

Mista

ashalingable wrote: »

Really really hate electrochemistry with a passion ........ Do you think I'll be ok leaving it out???

I hate it so.. so confusing with all the half reactions, what happens at each anode/cathode etc.. You probably could, it would most likely be one of the Q11 parts.

Duffman K wrote: »

when doing titration questions with : Vo x Mo/no = Vr x Mred/nr

I never know how to tell which is the oxidising agent and whic is the reducing agent ,

For example : na2co3 + 2hcl => 2nacl + co2 +h2o

Vo= Vr=
Mo = Mred =
no = nr =

any help would be appreciated.

Thats an acid base titration No oxidation/reduction involved.

Duffman K

Mista wrote: »

Thats an acid base titration No oxidation/reduction involved.

Oh ok, but say just in general, how do you know?

Liveforrugby

ashalingable wrote: »

Really really hate electrochemistry with a passion ........ Do you think I'll be ok leaving it out???

Yes, it only ever comes up as a part question in question 11

Duffman K wrote: »

when doing titration questions with : Vo x Mo/no = Vr x Mred/nr

I never know how to tell which is the oxidising agent and whic is the reducing agent ,

For example : na2co3 + 2hcl => 2nacl + co2 +h2o

Vo= Vr=
Mo = Mred =
no = nr =

any help would be appreciated.

You don't really need to know tbh, but if you do want to know it's the molecule which wants to gain electrons.

screeeewed wrote: »

Do we need to know the exact equations for le chateliers principle..? And do we need to know all three..or just one way to investigate it?

All 3 if you want to be safe

Mista

Duffman K wrote: »

Oh ok, but say just in general, how do you know?

Well.. in the equations for oxidation/reduction, there'll usually be charges on each molecule.. the ones which go lower are being reduced, and ones that go higher are being oxidised.

paddyhes

Duffman K wrote: »

Oh ok, but say just in general, how do you know?

There are some constants that wont change that you can determine it from:

Hydrogen (H) always has +1 apart from when it is in a metal hydride it has -1.

Oxygen (O) has -2 apart from when its in a peroxide then it can have -1 or if its in OF2 it has +2.

Halogens have -1 except when the join with a more electronegative element.

Determine oxidation values of each element on both sides of equation.
If the oxidation number increases it has been oxidised and that makes it the reducing agent.
If the oxidation number has decreased it has been reduced and that makes it the oxidising agent.

Duffman K

thanks for all the help

Darksider

Duffman K wrote: »

when doing titration questions with : Vo x Mo/no = Vr x Mred/nr

I never know how to tell which is the oxidising agent and whic is the reducing agent ,

For example : na2co3 + 2hcl => 2nacl + co2 +h2o

Vo= Vr=
Mo = Mred =
no = nr =

any help would be appreciated.

I think every oxidation-reduction titration involves either Potassium Manganate(VII) or Sodium Thiosulfate. Remember that as the first one is the main 'oxidising agent' on the course and the second is the main 'reducing agent.'

So if you get an experiment with sodium thiosulfate then you know that's the reducing agent and whatever the other one is will be the oxidising agent. Vice versa for KMnO4.

ei.sderob

There's really very little point in doing Electrochemistry. For such a small section of the paper, it's not really worth putting in the effort like.

Mista

ei.sderob wrote: »

There's really very little point in doing Electrochemistry. For such a small section of the paper, it's not really worth putting in the effort like.

Yeah, I'm not gonna bother doing it.. can spend my time on much better things.

Also, does anyone else not do any of the options? Our teacher said it was a waste of time

ei.sderob

We didn't do the options at all. Our teach had the same view!

partyatmygaff

Mista wrote: »

Also, does anyone else not do any of the options? Our teacher said it was a waste of time

I looked over the options for the first time the night before the exam. They're fairly straightforward but if you haven't covered them yet and aren't 100% on the main body of the course, I wouldn't bother.

ei.sderob

How much have ye been doing the night right before the exams? I mean, I've sorta had the view that all the work is done and it's just a case of refreshing stuff. 4 hours max like.

Mista

ei.sderob wrote: »

How much have ye been doing the night right before the exams? I mean, I've sorta had the view that all the work is done and it's just a case of refreshing stuff. 4 hours max like.

The actual night before the exam? Depends if I've had an exam already that day or not, and how screwed I think I am for it. I'd probably work til around 10, go to bed at 10, and maybe get up earlier than normal to study for it again.

FaoiSin

Options are easy enough

paddyhes

What are people revising day/night before?

Mista

paddyhes wrote: »

What are people revising day/night before?

Definitions probably.. and going over how to do tricky calculations. :pac:

ei.sderob

paddyhes wrote: »

What are people revising day/night before?

Just a general recap of stuff really. Nothing new, just gotta refresh some stuff. I'm not really one to do huge marathons of study. Just been tipping away all year so don't really have much to do.

paddyhes

ei.sderob wrote: »

Just a general recap of stuff really. Nothing new, just gotta refresh some stuff. I'm not really one to do huge marathons of study. Just been tipping away all year so don't really have much to do.

yeah same. just need the A1 and i've physics monday.
Haven't looked at chemistry since the exams started and it's easy to get rusty quick ya know.

ChemHickey

Electrochemistry is lovely. I really like it.

I hope for hard calculations as they're also my favourite part of the course.

If you want an a1 you shouldn't leave out any part of a course.

reznov

Why would you leave out electrochemistry? The fact that the chapter is minuscule in comparison to broader quests optics such as Water makes it so much more valuable if a full question comes up.

ei.sderob

ChemHickey wrote: »

Electrochemistry is lovely. I really like it.

I hope for hard calculations as they're also my favourite part of the course.

If you want an a1 you shouldn't leave out any part of a course.

I'm not so sure I agree with ya, leaving out the options is just fine as they're not HUGELY significant. An A1 is quite achievable without them.

Liveforrugby

ChemHickey wrote: »

Electrochemistry is lovely. I really like it.

I hope for hard calculations as they're also my favourite part of the course.

If you want an a1 you shouldn't leave out any part of a course.