Chemistry: Post your doubts here!

[nehaoscar]

KCN is used for the nucleophilic substitution of halegenoalkane with CN- ions ... not HCN

But then would HCN give a different product?
it will just form HBr instead of KBr right?
And suppose we said that happened then what would the HCl do? It will also form an acidic hydrolysis - COOH??

 

[nehaoscar]

Why is 1 wrong?
Will the pressure be equal?

 

[nehaoscar]

Help! it's 1 and 2 only
How would each react and what will it give in each case? And what would 3 give since it's wrong??

 

[BhaiArshad]

All will make aldehyde or carboxylic acid but which one is the one with low BP?

 

[BhaiArshad]

Why not B?
Answer is C

 

[goldenkatana]

uhm ... option 3 is wrong because the initial reactant isn't an ester ... only esters have this alkaline hydrolysis thingy to produce salt of acid ... nd 2nd option, i've never come accross it ... first is right coz the O-H bond will break and Na will take the place of hydrogen ...
but i am not sure ... if you know which year the paper is, plz do check the ms and lemme kno ...

But according to
http://www.chemguide.co.uk/organicprops/acids/acidity.html
It can react with all the three?

 

[awesomaholic101]

But then would HCN give a different product?
it will just form HBr instead of KBr right?
And suppose we said that happened then what would the HCl do? It will also form an acidic hydrolysis - COOH??

No ... i think HCN is too weak to even be used for this reaction ... i'm not sure if that is the reason but option C is perfectly correct, so why choose A instead?

 

[awesomaholic101]

But according to
http://www.chemguide.co.uk/organicprops/acids/acidity.html
It can react with all the three?

oh rite! sorry i totally forgot these basic acid-base reactions ... so probably A is the answer ...? ... don't you know which year it is??

 

[nehaoscar]

No ... i think HCN is too weak to even be used for this reaction ... i'm not sure if that is the reason but option C is perfectly correct, so why choose A instead?

So HCN is only used for reduction of aldehydes and ketones yeah?

 

[shazmina]

Help please!!!!

Use of the Data Booklet is relevant to this question. Which ions contain one or more unpaired electrons?
1 Cu2+
2 Mn3+
3 V3+

The Ans is A

V3+ has unpaired electrons??? :O

 

[awesomaholic101]

So HCN is only used for reduction of aldehydes and ketones yeah?

nucleophilic addition of aldehydes and ketones ... HCN is reagent .. KCN/NaCN is catalyst.

 

[princess Anu]

Reaction with Tollen's reagent results in a carboxylic acid OR carboxylate salt?

 

[nehaoscar]

How D? Wouldn't it be A :S

 

[Falconwing]

Why is 1 wrong?
Will the pressure be equal?

It will be equal. It can't be greater or it will keep expanding until equal

All will make aldehyde or carboxylic acid but which one is the one with low BP?

D? Besides, none of them are going to form aldehydes, they will form ketones. Carboxylic acids have higher boiling points bwecause of H-bonds. A and C form carboxylic acids, B forms nothing, and D forms ketone.

 

[awesomaholic101]

Help please!!!!

Use of the Data Booklet is relevant to this question. Which ions contain one or more unpaired electrons?
1 Cu2+
2 Mn3+
3 V3+

The Ans is A

V3+ has unpaired electrons??? :O

The electronic configuration of Vanadium is [Ar] 4s2 3d3 ...
In general, electrons are removed from the valence-shell s orbitals before they are removed from valence d orbitals when transition metals are ionized.
So, you have the following electronic configuration for V3+ : [Ar] 4s0 3d2
therefore, u got 2 unpaired electrons ...

 

[awesomaholic101]

Reaction with Tollen's reagent results in a carboxylic acid OR carboxylate salt?

carboxylate salt since Tollens' reagent is an aqueous solution of silver nitrate in excess ammonia solution ... alkaline condition means the acid formed is immediately neutralised to form the salt ...

 

[Falconwing]

View attachment 54844
How D? Wouldn't it be A :S

The oxygen is in excess, methane for example won't burn in a 1:7 ratio with oxygen! So the oxygen is left and the volume decreases as more oxygen is used up.

 

[shazmina]

2 moles of metallic salt react with 1 mole of sodium sulfite, oxidising sulfite needs 2 electrons. So, the original oxidation number of metal is +3, and there are two moles, so the new oxidation will be +2.

RTP apparently


Magnesium is second in it's group, so it would have the second smallest radius (because of more electron shells) and it has the third lowest ionisation after sodium and aluminium.. IE increases across the period, but Aluminium has an outer p subshell so it's IE is lower ^^

Sorry but i didnt get the Ionisation part :/

 

[shazmina]

The electronic configuration of Vanadium is [Ar] 4s2 3d3 ...
In general, electrons are removed from the valence-shell s orbitals before they are removed from valence d orbitals when transition metals are ionized.
So, you have the following electronic configuration for V3+ : [Ar] 4s0 3d2
therefore, u got 2 unpaired electrons ...

Omg i seriously forgot this sis A2 topic
Thank you sooo much JazakAllah khairan

 

[Falconwing]

Sorry but i didnt get the Ionisation part :/

IE naturally increases across the period because the nuclear charge is higher, so Mg wil lhavve more IE than Na. It will also have more IE than Al, because Al has an electron in the outer p shell which has more energy and is also farther than the nucleus. (Mg outer shell => 3s2, Al outer shell => 3s2 3p1)