Chemistry 21

[aka mohammed]

In the last question did the compund x had 2 carbons or 3 carbons

 

[user]

In the last question did the compund x had 2 carbons or 3 carbons

3

 

[Soldier313]

My teacher told me if i use higher pressure there will be no effect to equilibrium yield of methanol as kp or kc is not changed, is that right?

As far as i know a change in pressure does affect the equilibrium position when there are gases involved.....an increase in pressure favors the side with fewer moles, so in the case of methanol i think the products side was favored.....it is only the equilibrium CONSTANT that is not affected by a change in pressure...

 

[Jaf]

As far as i know a change in pressure does affect the equilibrium position when there are gases involved.....an increase in pressure favors the side with fewer moles, so in the case of methanol i think the products side was favored.....it is only the equilibrium CONSTANT that is not affected by a change in pressure...

Bingo!
Increasing the temperature decreased the yield and the catalyst had no effect.
What did you get your percentage purity as?

 

[Soldier313]

Bingo!
Increasing the temperature decreased the yield and the catalyst had no effect.
What did you get your percentage purity as?

yup temperature increase, decreased the yield
percentage purity - 90.8%....

 

[Soldier313]

Bingo!
Increasing the temperature decreased the yield and the catalyst had no effect.
What did you get your percentage purity as?

yup temperature increase, decreased the yield
percentage purity - 90.8%....

 

[user]

Bingo!
Increasing the temperature decreased the yield and the catalyst had no effect.
What did you get your percentage purity as?

aoa wr wb!
90.8%

 

[Jaf]

^That's what I got too.

How'd you guys tackle the question which asked us to prove the presence of 2 OH groups?
A lot of the kids I know found the molecular formula. :S

What I did was found the moles of X by mass/Mr of X (both of which were given) and then found the ratio of it with the moles of the hydrogen atoms. I got 2:1.

 

[Soldier313]

^That's what I got too.

How'd you guys tackle the question which asked us to prove the presence of 2 OH groups?
A lot of the kids I know found the molecular formula. :S

What I did was find the moles of X by mass/Mr of X (both of which were given) and find the ratio of it with the moles of the hydrogen atoms. I got 2:1.

whoa man! ditto! i did exaaaactly the same thing! found the moles of X and of H atoms...

 

[Thampi4]

guys, if i misspelled a word for example i wrote electrophillic instead of electrophilic do i loose marks

 

[Soldier313]

guys, if i misspelled a word for example i wrote electrophillic instead of electrophilic do i loose marks

i dunno:s i guess it's okay goes i think they do consider the what u've written if it resembles and is pronounced like the original terminology.....not very sure though:/

 

[iKhaled]

An increase in pressure, increased the yield or decreased it?

 

[iKhaled]

/ \
| COOH
| COOH the cyclohexane will look like this in q4 last part
\ /

for 3 it reacts with ethene....addition takes place...and bromo ethene is produced....where did u get thaat red brown gas?

Q4 last part the cyclohexene didnt get oxidises to carboxylic acid..this was a tricky question since the carbon is attached to 2 other methyl groups so it would be oxidised to a ketone, instead.

 

[Jaf]

Q4 last part the cyclohexene didnt get oxidises to carboxylic acid..this was a tricky question since the carbon is attached to 2 other methyl groups so it would be oxidised to a ketone, instead.

http://wwwchem.uwimona.edu.jm/lab_manuals/c10expt12.html

Yes, chemistry can be a troll sometimes.
Now you know why we worry about stuff that gets you '2-3' marks.

 

[iKhaled]

http://wwwchem.uwimona.edu.jm/lab_manuals/c10expt12.html

Yes, chemistry can be a troll sometimes.
Now you know why we worry about stuff that gets you '2-3' marks.

So is it an acid or ketone? :s

 

[iKhaled]

http://wwwchem.uwimona.edu.jm/lab_manuals/c10expt12.html

Yes, chemistry can be a troll sometimes.
Now you know why we worry about stuff that gets you '2-3' marks.

The link says it acid but we have studied that a secondary alc is oxidised to a ketone lol.. -___-

 

[Jaf]

The link says it acid but we have studied that a secondary alc is oxidised to a ketone lol.. -___-

There's the confusion.
Even though, 2 secondary alcohols DO form (in the intermediate), the bond between the two carbons which bear the alcohol functional groups breaks. This makes them primary alcohols which are then oxidized to aldehydes and further heating oxidizes the aldehydes to carboxylic acids.

Oh well. AS Chemistry is overrrr for me!

 

[iKhaled]

Do

There's the confusion.
Even though, 2 secondary alcohols DO form (in the intermediate), the bond between the two carbons which bear the alcohol functional groups breaks. This makes them primary alcohols which are then oxidized to aldehydes and further heating oxidizes the aldehydes to carboxylic acids.

Oh well. AS Chemistry is overrrr for me!

do uk if the high pressure increase yoeld or decrease it?

 

[Jaf]

Do do uk if the high pressure increase yoeld or decrease it?

I suppose it would increase it. That's what I wrote.

 

[leosco1995]

guys, if i misspelled a word for example i wrote electrophillic instead of electrophilic do i loose marks

No, you only lose marks if you misspell an actual chemistry term, for example writing "chlorine" instead of "chloride". Electrophillic is something minor so I highly doubt you will lose a mark there.