Chemistry: Post your doubts here!

[mohhef3]

someone help me out with que 30,28 and 23
http://maxpapers.com/syllabus-materials/chemistry-9701-a-level/attachment/9701_w14_qp_12/
and in que 32 what will differ in my calculations when i see that dot

 

[nehaoscar]

How to do this??

 

[asadalam]

Can someone explain these to me? Metanoia qwertypoiu

 

[nehaoscar]

Isn't it NaOH?

 

[nehaoscar]

How to do??

 

[Mathemagical]

View attachment 54753
Isn't it NaOH?

Chlorine will react with cold NaOH to form hydrogen and sodium chlorate (I).

 

[nehaoscar]

Why is the ratio 3:1 ?? (D)
The major product is the one with the less H-bonds right

 

[nehaoscar]

Why is 3 wrong? If something can form H-bonds then it will mix right?

 

[nehaoscar]

Why would 3 also occur?

 

[asadalam]

View attachment 54757
Why would 3 also occur?

You should give your book a reading once or twice.All of these are more or less simple and factual based.So revise and then see if you can solve for yourself.

 

[mohhef3]

someone help me out with que 30,28 and 23
http://maxpapers.com/syllabus-materials/chemistry-9701-a-level/attachment/9701_w14_qp_12/
and in que 32 what will differ in my calculations when i see that dot

 

[BhaiArshad]

Help.
asadalam
qwertypoiu

 

[qwertypoiu]

http://s21.postimg.org/vl3ml18xy/new_one.jpg
qwertypoiu The Sarcastic Retard can you please help me with this question ...
As far as i know, secondary alcohols when oxidised to ketones donot respond to mild oxidising agents, so i thought it might be a secondary alcohol, but is it wrong? can you pls clarify, the ans is D

Compound X can be dehydrated --> it's an alcohol
Compound X cannot be oxidised ---> it's a tertiary alcohol.
Tertiary alcohol was dehydrated, so the resulting compound must have a double bond connected to a carbon atom that is connected to three other carbon atoms, which is only D.

 

[nehaoscar]

How to do??

 

[qwertypoiu]

How to do??

CH3CH2OH + 2[O] ---> CH3CO2H + H2O
Mass of ethanol = 2.76g
Mr of ethanol = 12*2 + 5 + 16 + 1 = 46g/mol
Moles of ethanol = 2.76g / 46g/mol = 0.06mol
Moles of acid = 0.06mol
Mr of acid = 12*2 + 3 + 16*2 + 1 = 60g/mol
Theoretical mass of acid = 0.06mol * 60g/mol = 3.6g
Actual mass = 75% * 3.6g = 2.70g

 

[BhaiArshad]

qwertypoiu

 

[shazmina]

Compound X can be dehydrated --> it's an alcohol
Compound X cannot be oxidised ---> it's a tertiary alcohol.
Tertiary alcohol was dehydrated, so the resulting compound must have a double bond connected to a carbon atom that is connected to three other carbon atoms, which is only D.

Thank you so much i got it

 

[shazmina]

The question says that it is unreactive towards mild oxidising agents which mean it can not be a primary or a secondary alcohol as both can be oxidised .
It has to be a tertiary alcohol which is only possible in D

Thank you so much Brother.

 

[princess Anu]

Q21: Can someone explain these to me? Metanoia

If the compound was an alkane and had no rings or double bonds, number of H atoms present = 2n+2 = 2(20)+2 = 42

Now, every time there're 2H less, you'll either have a double bond or a ring. The question states that there's one aldehyde (C=O) and 1 ring structure which has 1 C=C so this accounts for 6 missing Hydrogens, thereby leaving you with 8 missing Hydrogens.

8/2 = 4 Hydrogens in the aliphatic side chain.

However, total C=C are 5 because you have to include the C=C from the cyclohexene + cis formation hence A

I have attached the solution for Q11

 

[qwertypoiu]

qwertypoiu

Al2O3 does not dissolve in water.

Na2O + H2O ----> 2Na(OH)
See, one mole of Na2O makes 2 moles of OH- ions.

P4O10 + 6H2O ---> 4H3PO4
See, one mole of P4O10 makes 4 moles of H+ ions.

SO3 + H2O ----> H2SO4
See, one mole of SO3 makes 2 moles of H+ ions.

For complete neutralization, same number of H+ and OH- ions must exist.
Therefore, answer is D.