** Chemistry 2017

daraghwal

Does anyone here do chemistry? Do you know is this experiment still on the course? I can't find it in the book. It's 2007 Q2. A sample of ethanoic acid (CH3COOH) was prepared by the oxidation of ethanol using the apparatus shown.

gavinoontheweb

daraghwal wrote: »

Does anyone here do chemistry? Do you know is this experiment still on the course? I can't find it in the book. It's 2007 Q2. A sample of ethanoic acid (CH3COOH) was prepared by the oxidation of ethanol using the apparatus shown.

Latest changes to LC Chem in here, http://www.gillmacmillan.ie/AcuCustom/Sitename/DAM/060/LSMS_Chemistry_Changes_to_the_Experimental_Work.pdf
Hoping for Iron/Bleach, Soap/Eugenol, Volatile Liquid on experiments

hasdanta

daraghwal wrote: »

Does anyone here do chemistry? Do you know is this experiment still on the course? I can't find it in the book. It's 2007 Q2. A sample of ethanoic acid (CH3COOH) was prepared by the oxidation of ethanol using the apparatus shown.

It's not on the course anymore.

Mr Rhode Island Red

daraghwal wrote: »

Does anyone here do chemistry? Do you know is this experiment still on the course? I can't find it in the book. It's 2007 Q2. A sample of ethanoic acid (CH3COOH) was prepared by the oxidation of ethanol using the apparatus shown.

As far as I know anything involving chromates and dichromates was taken off the course. We don't have to know the preparation of ethanoic acid but we do have to know it's properties.

Skodaa

I was pretty good at Chemistry during 5th year mainly because of the teacher but that teacher took a teaching job in Dubai for 6th year and the replacement hasn't be great so I really fell off, does anyone have good topics to look over for the exam? please and thanks

i am awsome

Atomic Theory & Organic make up half (or even more) of the exam, focus on those. Q1 - study the experiments, pretty much guaranteed 50marks Q2 - study organic experiments, also guaranteed 50 marks. Q4 - short Q's, know your definitions (eg: Le Chatelier's Principal, v. frequent)

daraghwal

Q5 is always atomic theory, Q6 is always fuels and heats of reactions mixed with a bit of organic. You're almost guaranteed a bit on water and then the reaction schemes almost always come up too.

Skodaa

does anyone have the DEB chemistry pre marking schemes? or answers mostly correct?

Ponguin

Skodaa wrote: »

does anyone have the DEB chemistry pre marking schemes? or answers mostly correct?

Not sure whether mine is DEB or Examcraft, it has volatile liquids and iron tablets I think?

gavinoontheweb

Does anyone know if diagrams like these are suitable for the mechanism of ionic addition, I'm fairly certain it will come up tomorrow?

thetalker

seems alright, make sure to have explanations and a heading for each.

Anyone revising for any specific exp? I don't actually know a lot of them (poor teacher) and was hoping to focus on a few.
So far I've done the iron tablet, clove oil, ethene and ehtyne, the bleach one, volatile liquid, oh and water hardness.

Any other biggies people imagine?

daraghwal

thetalker wrote: »

seems alright, make sure to have explanations and a heading for each.

Anyone revising for any specific exp? I don't actually know a lot of them (poor teacher) and was hoping to focus on a few.
So far I've done the iron tablet, clove oil, ethene and ehtyne, the bleach one, volatile liquid, oh and water hardness.

Any other biggies people imagine?

Soap?

thetalker

Looks like the iron tablet and ethene/ethyne came up so that was grand.
What did people get for the Kc value and that question on the acids. Wasn't too sure on those.

Ponguin

thetalker wrote: »

Looks like the iron tablet and ethene/ethyne came up so that was grand.
What did people get for the Kc value and that question on the acids. Wasn't too sure on those.

Think I got around 0.732 mol/l of product in reaction vessel for the Kc one!

thetalker

Same! But a friend pointed out you have 2 moles on the right so maybe you had to multiply that by two?

dorado99

Did anyone else use the factor formula, then discarded negative value and use the positive value?

Ponguin

No I think that's accounted for when you use the equilibrium constant formula as the [No2] or whatever was squared, I hope

Ponguin

dorado99 wrote: »

Did anyone else use the factor formula, then discarded negative value and use the positive value?

Yeah I used the -b

dorado99

i got x/20 for product which was squared to get x^2/400 then 1-x for thereactant. So put that into kc you have a variable ^2

wanderer100

Ponguin wrote: »

Yeah I used the -b

Yeah so did I

daraghwal

I got this? Is that not right?

thetalker

dorado99 wrote: »

i got x/20 for product which was squared to get x^2/400 then 1-x for thereactant. So put that into kc you have a variable ^2

Why x/20?

thetalker

daraghwal wrote: »

I got this? Is that not right?

0.1 is what you put in, at equilibrium it will be 0.1-x as in whatever it loses and turns into the product

Ponguin

My formula was X^2 +2X -2 =0 so whatever the positive root is of that I got

dorado99

thetalker wrote: »

Why x/20?

the Ec value was X/2 /10 . Since there is a 2 in front of the product , the change in equilibrium and in turn at equilibrium the value is x/2 . Then divide it by the number of litres which is 10. So 0.5x/10 is x/20.

Consonata

thetalker wrote:

0.1 is what you put in, at equilibrium it will be 0.1-x as in whatever it loses and turns into the product

Was it not be 1 - x at equilibrium and then divided by 10 to get 0.1 - 0.1x

Mr Rhode Island Red

Anybody get 32 for the relative molecular mass of the volatile liquid in question 10?

Not a bad paper, thought Q4 was fierce tricky compared to how straightforward it normally is.

dorado99

Did you guys get a positive number in hundreds (+100s) for Hess' calculation?

thetalker

Mr Rhode Island Red wrote: »

Anybody get 32 for the relative molecular mass of the volatile liquid in question 10?

Not a bad paper, thought Q4 was fierce tricky compared to how straightforward it normally is.

I got something around that yeah

First 6 questions were nice, the other two Q9 and Q10 for me, were a bit trickier.

Ponguin

Mr Rhode Island Red wrote: »

Not a bad paper, thought Q4 was fierce tricky compared to how straightforward it normally is.

Yeah usually I do all the short questions with hardly any bother but today only did 9 I think, some of them like the eugenol one looked fairly tricky at first glance but turned out to be okay in the end

Manufan123

dorado99 wrote: »

Did you guys get a positive number in hundreds (+100s) for Hess' calculation?

Yes around 180 rings a bell