**Chemistry...Before/After

leaveiton

Does everyone else's teacher reckon atmospheric chemistry will come up for option 1 this year? I don't think we did anything on industrial at all...

TheHazer

Last exam is so hard to study for.... I'm counting this as study!

paddyhes

Does anyone know where i can find all the experiments in one handy place?

Pepperr

paddyhes wrote: »

Does anyone know where i can find all the experiments in one handy place?

Your book.

reznov

Delta H of reaction is equal to delta H of products minus delta H of reactants. This is Hess' law, stick by the rules. The other method is too long.

paddyhes

Pepperr wrote: »

Your book.

Ha.

Hayezer

How do I do heat of formation ? Tried it heat of combustion way, it doesn't wooorrkkk

Mista

Hayezer wrote: »

How do I do heat of formation ? Tried it heat of combustion way, it doesn't wooorrkkk

Heat of formation is just adding the elements to make whatever.. whats the question?

Liveforrugby

Good luck to everyone, may Zeus be with you. Imma fail so I'd appreciate if you'd all light a candle for me.

Megan.mcgowan

Could someone pleeeease write up a quick summary of the Winkler exp and the chlorine swimming pool one.. My teacher flew through the last few experiments because we were under pressure to finish the course.

Also do you think i'd be okay knowing these topics? (hoping to scrape a C3)
Fuels and Thermochem,
Organic,
Water,
Periodic Table and all that crap.. Radioactivity, trends in p. table, identifying anions,
Most definitions..

Need to revise the exps thinking of just doing the titrations, ethanal/ethanoic acid, volatile liquid and then winkler and the chlorine one cause im running out of time

Any help would be so great!!

Mista

Megan.mcgowan wrote: »

Could someone pleeeease write up a quick summary of the Winkler exp and the chlorine swimming pool one.. My teacher flew through the last few experiments because we were under pressure to finish the course.

Also do you think i'd be okay knowing these topics? (hoping to scrape a C3)
Fuels and Thermochem,
Organic,
Water,
Periodic Table and all that crap.. Radioactivity, trends in p. table, identifying anions,
Most definitions..

Need to revise the exps thinking of just doing the titrations, ethanal/ethanoic acid, volatile liquid and then winkler and the chlorine one cause im running out of time

Any help would be so great!!

Well we have a guaranteed Organic and titration question anyway.


Winkler:
-Rinse out bottle. Removes air bubble/impurities.
-Submerge bottle completely in water to be analysed.
-Use dropper with end under surface of water, add Maganese (II) Sulfate solution. Use another dropper to add alkaline pottasium iodide solution (KI).
-Stopper bottle, shake for half a minute.
-Allow brown ppt to settle until there is a few cm depth of clear liquid at top.
-Use dropper again to add concentrated sulfuric acid.
-Restopper and shake to dissolve ppt.
-Solution should be reddish brown due to liberated iodine.
-Place this solution in conical flask, sodium thiosulfate in burette, titrate as normal.
-End point/indicator is same as iodine/sodium thiosulfate titration.
-In calculation, they usually want p.p.m of 02, this is the same as mg/L.
-Ratio is usaully 1:4

Also, white ppt is formed first before adding acid.
Mn+2 + 2OH- --> Mn(OH)2 ppt (manganese (II) hydroxide)

This reacts with oxygen to form brown ppt.
4Mn(OH)2 + O2 + 2H20 --> 4Mn(OH)3 ppt (manganese (III) hydroxide)

If white ppt does not turn brown, no oxygen in water.

Pepperr

Good summary!.

Naomi00

Pepperr wrote: »

Your book.

Haha, except our book is mostly; 'waffle,waffle,waffle-thing you need to know - waffle, random irrelevant story,waffle', and continue for a few hundred pages.

I can see why they'd want a better version of experiments if their book is as bad as ours, 'Chemistry Live'

Megan.mcgowan

Mista wrote: »

Well we have a guaranteed Organic and titration question anyway.


Winkler:
-Rinse out bottle. Removes air bubble/impurities.
-Submerge bottle completely in water to be analysed.
-Use dropper with end under surface of water, add Maganese (II) Sulfate solution. Use another dropper to add alkaline pottasium iodide solution (KI).
-Stopper bottle, shake for half a minute.
-Allow brown ppt to settle until there is a few cm depth of clear liquid at top.
-Use dropper again to add concentrated sulfuric acid.
-Restopper and shake to dissolve ppt.
-Solution should be reddish brown due to liberated iodine.
-Place this solution in conical flask, sodium thiosulfate in burette, titrate as normal.
-End point/indicator is same as iodine/sodium thiosulfate titration.
-In calculation, they usually want p.p.m of 02, this is the same as mg/L.
-Ratio is usaully 1:4

Also, white ppt is formed first before adding acid.
Mn+2 + 2OH- --> Mn(OH)2 ppt (manganese (II) hydroxide)

This reacts with oxygen to form brown ppt.
4Mn(OH)2 + O2 + 2H20 --> 4Mn(OH)3 ppt (manganese (III) hydroxide)

If white ppt does not turn brown, no oxygen in water.

Thanks thats a big help! Would you defo need to know them wee equations yeah? Im useless at remembering them! :L

Mista

Pepperr wrote: »

Good summary!.

A bit brief, but its all you really need to know.. and that was my revision done for it typing that out :P

Naomi00 wrote: »

Haha, except our book is mostly; 'waffle,waffle,waffle-thing you need to know - waffle, random irrelevant story,waffle', and continue for a few hundred pages.

I can see why they'd want a better version of experiments if their book is as bad as ours, 'Chemistry Live'

We have that as well.. waay to much information, and they even say that the information is irrelevant half the time themselves ("but you dont need to know this for LC level"). I wish I had gotten a revision book

Hayezer

Understanding Chemistry is the worst book I have, doesn't even have an experiments contents page

reznov

Chemistry Live is alright. Some parts of it are atrocious.

Mista

Megan.mcgowan wrote: »

Thanks thats a big help! Would you defo need to know them wee equations yeah? Im useless at remembering them! :L

Nah, proably not. I'd suggest going over the question from the one time it came up, 2005.
http://www.examinations.ie/archive/exampapers/2005/LC022ALPO00EV.pdf
Q1

abbeymate

Hey I was just wondering what experiments do we need to know the equations by heart for? :-S Dire straits now!! Thanks

Hayezer

Lads in organic, how do you tell if a reaction is addition, substitution or elimination?

Mista

abbeymate wrote: »

Hey I was just wondering what experiments do we need to know the equations for?

Test for anions definatley.
Preparation of ethene, ethyne, ethanal, ethanoic acid. Soap.
Oh, and for rates of reaction, know hydrogen peroxide, and a metal in acid. Also, reaction between HCl and Na2S2O3.
Le Chateliers Principle (I think).

In titrations your given them.

Mista

Hayezer wrote: »

Lads in organic, how do you tell if a reaction is addition, substitution or elimination?

If things are added, its addition. Alkenes and alkynes usually undergo this, where a double bond is broken.

Substitution is where things are replaced. Like alkanes added to Cl2 in UV light, to make chloroalkanes.

Elimination is where things are taken out, like a water molecule from ethanol to make ethene.

If you get stuck, draw out the reactant and product and see whats goin on :P

abbeymate

Mista wrote: »

abbeymate wrote: »

Hey I was just wondering what experiments do we need to know the equations for?

Test for anions definatley.
Preparation of ethene, ethyne, ethanal, ethanoic acid. Soap.
Oh, and for rates of reaction, know hydrogen peroxide, and a metal in acid. Also, reaction between HCl and Na2S2O3.
Le Chateliers Principle (I think).

In titrations your given them.

Thanks for your help! Are we given every equation we need for the titrations or do we need to know a few?
Also, what experiments does everyone think will come up this year? B-)

Mista

abbeymate wrote: »

Thanks for your help! Are we given every equation we need for the titrations or do we need to know a few?
Also, what experiments does everyone think will come up this year? B-)

No bother Your given them, or the ratios.. all you need are the ratios :P

My teachers convinced that hydrates sodium carbonate is coming up :P And I think that volatile liquid has a good chance of appearing... hate that one As for organic, maybe ethanal/ethanoic acid.. but I'm going over eveything, not gna do a Plath on chemistry :P

DepoProvera

Mista wrote: »

hydrates sodium carbonate

What is this?

Liveforrugby

Why is sulfuric acid needed in the preparation of ethanal. What's it's function?

Mista

DepoProvera wrote: »

What is this?

Hydrated. My bad :P the water of crystallisation one

abbeymate

Mista wrote: »

abbeymate wrote: »

Thanks for your help! Are we given every equation we need for the titrations or do we need to know a few?
Also, what experiments does everyone think will come up this year? B-)

No bother Your given them, or the ratios.. all you need are the ratios :P

My teachers convinced that hydrates sodium carbonate is coming up :P And I think that volatile liquid has a good chance of appearing... hate that one As for organic, maybe ethanal/ethanoic acid.. but I'm going over eveything, not gna do a Plath on chemistry :P

Yeah, I really agree with you!! It's exactly what I was thinking, well what my was teacher thinking :-P Well I was lucky with kavanagh.. NO must study EVERYTHING! :L

DepoProvera

Liveforrugby wrote: »

Why is sulfuric acid needed in the preparation of ethanal. What's it's function?

Supplies H+ ions for oxidation afaik.. Not sure though!

Hayezer

Mista wrote: »

If things are added, its addition. Alkenes and alkynes usually undergo this, where a double bond is broken.

Substitution is where things are replaced. Like alkanes added to Cl2 in UV light, to make chloroalkanes.

Elimination is where things are taken out, like a water molecule from ethanol to make ethene.

If you get stuck, draw out the reactant and product and see whats goin on :P

Thanks a mill !