OCR Chemistry F322~ 4th June 2013~ AS Chemistry

OP

Original post by needtosucceed=)

this is what I was thinking. i'm pretty sure double bonds on the 1st carbon can still show e/z.

You just should not have only one group of atoms attached to the double bond carbon, it always has to be two? :smile:

Reply 1561

Original post by Jimmy20002012

You just should not have only one group of atoms attached to the double bond carbon, it always has to be two? :smile:

yep, so for example hclc=chcl would show e/z

as would ClHC=CClCH3
theres 3 carbons in that example, the double bond is on the first carbon but both carbons are still attached to 2 different atoms/groups of atoms

Reply 1562

Original post by carpe diem 123

Hey, where can I find this list of definitions?

page 76 or 77

Reply 1563

Original post by Jonma

Can someone please explain this question?
chem ques.png

I explained that to someone a few days ago, go back to somewhere between pages 60-70 and you should find it :smile:

Reply 1564

Smko

Original post by Jimmy20002012

Not sure that is completely right, as if you see the Jan 13 mechanism 12 marker the end product in nucleophillic substitution has an OH group as well as containing ImageUploadedByStudent Room1370181585.957891.jpg

ImageUploadedByStudent Room1370181585.957891.jpg

a double bond :smile:

that is not an alcohol though. It has an OH Group attacted ..does mean it is an alcohol . But yeah i understnad what the OP meant now :P sorryyy!

Reply 1565

OP

Original post by needtosucceed=)

yep, so for example hclc=chcl would show e/z

as would ClHC=CClCH3
theres 3 carbons in that example, the double bond is on the first carbon but both carbons are still attached to 2 different atoms/groups of atoms

How is hclc=chcl e/z isomerism as they are the same group of atoms on each carbon? :redface:

Reply 1566

Anonymous1717

Original post by carpe diem 123

Hey, where can I find this list of definitions?

Pg 76 post 1504

Reply 1567

Original post by Jimmy20002012

How is hclc=chcl e/z isomerism as they are the same group of atoms on each carbon? :redface:

each carbon has 1 hydrogen and 1 cl atom. definition of e/z is when each carbon is bonded to 2 different atoms.

Reply 1568

OP

Original post by needtosucceed=)

each carbon has 1 hydrogen and 1 cl atom. definition of e/z is when each carbon is bonded to 2 different atoms.

Ohhh okay, thanks for that :smile:

how many exams you got next week then?

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Reply 1569

Original post by Jimmy20002012

Ohhh okay, thanks for that :smile:

how many exams you got next week then?

Posted from TSR Mobile

its alright :smile:

i've got 3, 2 on tuesday then 1 on thursday..you?

Reply 1570

OP

Original post by needtosucceed=)

its alright :smile:

i've got 3, 2 on tuesday then 1 on thursday..you?

I have got 2 to tomorrow and then one everyday till Thursday :frown:

Reply 1571

Original post by Jimmy20002012

I have got 2 to tomorrow and then one everyday till Thursday :frown:

ah that sucks :frown:

what have u got tomorrow?

Reply 1572

lucy3003

Original post by Jonma

Can someone please explain this question?
chem ques.png

Not sure if I'll be good at explaining this: you need to cancel out anything you have on both sides of the equations in the diagrams, then it will be one of the equations in the table so you put in the correspond enthalpy change. So for the bottom equation for example; you have CaCl2 and H2O on both sides so you can cancel them out and you're left with C + O2 --> CO2 which is the top equation in the table so for that oone in the diagram the enthalpy change is -393,, does that make sense? And then you add them up using Hess's law

(edited 10 years ago)

Reply 1573

OP

Original post by needtosucceed=)

ah that sucks :frown:

what have u got tomorrow?

Biology and IT :frown:

Reply 1574

Gotzz

13

Can someone please explain Q3bii on January 2012.
It's the question about enthalpy of formation where they've drawn a cycle and you have to fill in the boxes.
I got the top 3 correct, but I don't get the rest.
Thanks

Reply 1575

lucy3003

Hey could someone possibly explain how to do june 10 question 6 (c)(i)?

Reply 1576

Original post by Gotzz

Can someone please explain Q3bii on January 2012.
It's the question about enthalpy of formation where they've drawn a cycle and you have to fill in the boxes.
I got the top 3 correct, but I don't get the rest.
Thanks

if you've got 3 of them correct theres only 1 box left so just use the value you havent used yet?

Reply 1577

Polypocus

Hi guys, there a question on the June 2009 Paper namely, 2c (ii) where it asks us to write the state symbols for an equation.
The equation is 6C + 7H2 --> C6H14 (Hexane)
Another piece of information we were given was that Hexane melts at -95 degrees Celsius and boils at 65 degrees Celsius

Now Carbon is a solid in its standard state and hydrogen is a gas but how exactly are we supposed to know that Hexane is a liquid?
Is that just something we should know or am I missing something :s
Thanks :smile:

Reply 1578

lucy3003

Original post by Polypocus

Hi guys, there a question on the June 2009 Paper namely, 2c (ii) where it asks us to write the state symbols for an equation.
The equation is 6C + 7H2 --> C6H14 (Hexane)
Another piece of information we were given was that Hexane melts at -95 degrees Celsius and boils at 65 degrees Celsius

Now Carbon is a solid in its standard state and hydrogen is a gas but how exactly are we supposed to know that Hexane is a liquid?
Is that just something we should know or am I missing something :s
Thanks :smile:

I'm not sure but I think its because hexane is a component of crude oil which is a liquid?

Reply 1579