Question

Question 34

Answer 1

@aaronq

Answer 2

Is there an Answer key from which the answer can be confirmed?

Answer 3

in an organic synthesis 60% yield of product is achieved. which of these conversions are consistent with this information
1) 74 g of butan-2-ol -> 44.64 g of butanone
2)74 g of butan-1-ol -> 54.56 g of butanoic acid
3) 74 g of 2-methylpropane-1-ol -> 54.56 g of 2-methylpropanoic acid

Answer 4

Another question ^

Answer 5

According to me, the answer is 2.

After 2 minutes, the sulfuric acid has produced more gas than ethanoic acid.

Answer 6

Yes for 34 all are correct

Answer 7

Ok so we can choose more than 1 option?

Answer 8

The answer is 1.
74 g of butan-2-ol -> 44.64 g of butanone

Answer 9

Yeah the options are
A. 1, 2 and 3
B. 1 and 2
C. 2 and 3
D. 1 only

Answer 10

Oh okay, then it's A.

Answer 11

Same goes for the second question A all three are correct

Answer 12

Sulfuric Acid is a stronger acid than Ethanoic Acid which is a weak acid.

A Strong Acid fully dissociates Hydrogen ions in a solution, a weak Acid partially dissociates (gives out Hydrogen ions).

More dissociation of Hydrogen ions would mean more amount of gas (hydrogen gas) released in the reaction, and the faster it would be released as the concentration of Hydrogen ions is greater.

Answer 13

I wouldn't know about the second question cause that's the first time i'm facing that kind of a situation in Chemistry. Hopefully you understood the first Question's answer!

Answer 14

Sulfuric Acid would also be at a higher temperature because, both reactions being exothermic (release heat, i.e heat 'exit'), the Stronger Acid would be more hotter as the energy/heat released in bond formation would be greater as Greater number of bonds are being made, as it's concentration is greater.

Answer 15

Oh alright

Answer 16

But Sulphuric acid's concentration is same as ethanoic acid.

Answer 17

Yes, the MOLECULES concentration is same. But the amount of Hydrogen ions Sulfuric Acid 'donates' to the solution is Greater than Ethanoic Acid.

Sulfuric Acid donates almost ALL of it's Hydrogen ions, whereas Ethanoic acid donates partially.

Answer 18

Ohhhh i got it now

Answer 19

So how about second question?

Answer 20

For example. The Circles represent the 'MOLECULES' of the acid, and the Circles with 'X' in them are the ones that 'donate' hydrogen ions.

Hope you got it now!

Answer 21

Ahaha Nice nice i got it now thanks so much

Answer 22

I don't really know about the Second question, I can't say because I just used this:

\[\frac{ 60 }{ 100 } \times 74 = 44. 4\]

The good ol' math way, but if all are correct then I wouldn't know, this might have a Chemistry side to it.

Answer 23

Maybe it's that it's not EXACTLY 60% yield, as NOTHING can be perfect in Science except Theoretically speaking. The Theoretical Yield must be 44.4g, but Experimental yield can differ by a little.

Answer 24

I used the same method i got an A in olevels maths :v but alevel maths dissapointed me gave the exams recently not went good sigh.

Answer 25

Hahaha Nice Nice! I JUST got done with my O'Levels. Gave the CIEs a week or two ago.
I was very very very bad at Chemistry, I hated it, but I got to know this teacher and man (maybe you're a girl ahah), he made me fall in love with Chemistry in so little time. I'm still trying to perfect it.

Answer 26

I've failed Maths since 6th grade lol, i'm really bad at it, you have no idea. But the CIEs went pretty good it's hard for even me to believe >.>

Answer 27

Dua kero meray bhi achay ho jaen.

Answer 28

I just freaked you out a little right??

Answer 29

HAHAHAH OMFG XD
iA iA Achay ho jayen ge, pellet DAMN! xD

Answer 30

sh!t* :@

Answer 31

Yeah Good morning.

Answer 32

It's.. :|
4 AM, but yeh Good Morning! Goodluck though!

If you need any more help (from an O'Level student lol) feel free to ask, i'll be on my way to help someone else!

Answer 33

Azaan ho gae hae iss liey mein ne kaha

Answer 34

Umm btw if you're in Lahore, try studying from Sir Mohammad Ali.
That's the BEST Chemistry teacher you'll ever meet. EVER.

Answer 35

Specially for A'Level students.

Answer 36

No not in Lahore.

Answer 37

Ok so I just realized the answer to Question 34 is 1 and 2.

Answer 38

and 3. all three are correct

Answer 39

No, not 3. I also thought 3 but I read the Question again. Only 1 and 2.
If your Answer Key says all 3 are correct, i'd bet 9.9/10 that it's wrong.

Answer 40

today's my exam i hope this doesn't come up :o. why cannot C be though?

Answer 41

My Cousin's exam is today too, He's doing AS. I confirmed it from him. Lemme see if I can explain

Answer 42

OK I forgot what that rule was named (after the scientist) which told us how to make the reactions go in forward direction (pressure, temperature, moles, concentration), if you remember, you can remind me.

Answer 43

Ok I remember, it was Le Chatelier's principle.

Answer 44

whats the problem in it? carboxylic acids are weak acids....

Answer 45

that was easy it just slipped out of my mind

Answer 46

so obviously h2so4 would give less yield

Answer 47

Ann-Hybrid why its A in the markscheme then

Answer 48

Anyways, the thing is. When the partially dissociated hydrogen ions in weak acid get used up and are released as Hydrogen gas, their concentration decreases in the solution, which causes the acid to release MORE Hydrogen ions. This keeps on happening till all the hydrogen ions are released from the acid and at the end, the gas would be the same amount as of Sulfuric acid, as their volume and concentration is same.

Answer 49

Ann-Hybrid it's something you won't understand.

Answer 50

rostella

Answer 51

Get it?

Answer 52

is common sense....that h2so4 would give more yeild at any point

Answer 53

but ofcourse its Common sense

Answer 54

Ann-Hybrid stop it now i'm trying to focus here

Answer 55

kay...u focus..

Answer 56

The difference is, the Sulfuric Acid reaction would be faster and more 'intense' (exothermic) as the frequency of fruitful collisions is greater due to it's concentration of Hydrogen Ions. At one time, GREATER Number of ions are released, whereas in the Organic Acid, it's weak and at one time, less number are being released and when they escape as Hydrogen gas, the decrease in concentration causes them to release more Hydrogen ions.

Answer 57

I thought the same @Disco619 but just got confused when i saw the markscheme it sure is misleading

Answer 58

You just have to trust yourself, I also had trouble cause Marking scheme does lower your confidence sometimes. Goodluck!

Answer 59

no wait you said earlier that weak acid dissociates partially it won't give much OH ions so 3 can be correct in this way

Answer 60

Not 'OH', 'H' ions.

Answer 61

i get it i get it it will be used up by the end of reaction.

Answer 62

Yes they DO Dissociate partially! But when the - whatever dissociated ions - in the solution escape (as H2 in this case), their concentration decreases, which causes the weak acid to dissociate MORE of it's ions. Then they get used up, more are released, they're used up and so on... Till the acid runs out of Hydrogen ions to be released (as the metal was in excess)

Answer 63

oh yeah H ions

Answer 64

ohh so markscheme is a lie. oh well.

Answer 65

Yup!