Chemistry: Post your doubts here!

[The Sarcastic Retard]

Help please!!!!!!!!!
The conversion of graphite into diamond is an endothermic reaction (∆H = +3 kJ mol–1).

C(graphite) → C(diamond)

Which statements are correct?

1 The enthalpy change of atomisation of diamond is smaller than that of graphite.

2 The bond energy of the C–C bonds in graphite is greater than that in diamond.

3 The enthalpy change of combustion of diamond is greater than that of graphite.

Ans is A

https://answers.yahoo.com/question/index?qid=20130526190233AAoa9RU

 

[shazmina]

View attachment 54537
Why??

it cant be option A or D .. and the only 2 choices are B and C ..
as u see ... Sulfuric acid is a dehydrating agent and there fore dehydrates Alcohol to alkene ...
And we also know that Alkenes reacts with Sulfuric acid therefore we purify them with dilute NaOH ie option C

 

[shazmina]

The question says: "Which chlorine compound has bonding that can be described as ionic with some covalent character?"
AlCl3 is actually a covalent compound, it's NOT ionic. Aluminium OXIDE, which reacts with both acids and bases, lis amphoteric.
NaCl when dissolved in water forms a solution with pH of 7. It forms Na+ ions and Cl- ions. It is completely ionic. AlCl3, being covalent (and not ionic), hydrolyses in water and forms Al(OH)3 and HCl. The resulting solution has a pH of 3.
MgCl2 can be described as ionic but forms a solution with pH of 6.5 when dissolved in water. The slight acidity is attributed to the slight covalent character.
So again, AlCl3 cannot be described as ionic, rather it is a covalent compound. So the right answer is MgCl2.

The reason for covalency in AlCl3 is the high charge density of Aluminum ion, and large electron cloud of chlorine atom. Aluminum fluoride, for example, is ionic, since fluorine electron clouds are not large enough to be polarised by aluminum ion.

Amazing (Y)

 

[Metanoia]

View attachment 54536
Isn't AlCl3 dimeric covalent? but answer is B...??

Question is asking about AlCl3 (covalent) , not AlCl3 dimer (Al2Cl6).

Ok but then the question only asks about AlCl3 right (which thus is ionic with covalent character)
The link doesn't say that MgCl2 is ionic with covalent character
So then why is the answer MgCl2 that has an ionic structure with covalent character?
Why not AlCl3?
I'm sooo confused on this one xD

AlCl3 is ionic with a LOT of covalent character but as it vaporises, its structure changes to covalent from ionic.

In bonding, a complete transfer of electrons results in a "perfect" ionic compound .
An equal sharing of electrons results in a "perfect covalent" compound.

This can be seen as opposite ends of a spectrum.

100% ionic ........................100 % covalent

Most compounds lie inbetween
100% ionic ..........ionic with covalent character................covalent with ionic character.....100% covalent.

When a compound is "ionic with a lot of covalent character" as described by you, it is actually more correct to say " covalent with ionic character".

 

[princess Anu]

During dehydration, the OH is removed with a neighboring H atom (either the red dot or blue dot).

View attachment 54528
Removing the OH and H atom at the red dot gives us option D.

But removing H atom at the blue dot gives us option C too ;/ How do we know which C ( red Or blue) shud lose H?

 

[nehaoscar]

It's not a reaction undergone by hydroxyl grps

So the reagents could be PCl5 or SOCl etc...?

 

[nehaoscar]

The question says: "Which chlorine compound has bonding that can be described as ionic with some covalent character?"
AlCl3 is actually a covalent compound, it's NOT ionic. Aluminium OXIDE, which reacts with both acids and bases, lis amphoteric.
NaCl when dissolved in water forms a solution with pH of 7. It forms Na+ ions and Cl- ions. It is completely ionic. AlCl3, being covalent (and not ionic), hydrolyses in water and forms Al(OH)3 and HCl. The resulting solution has a pH of 3.
MgCl2 can be described as ionic but forms a solution with pH of 6.5 when dissolved in water. The slight acidity is attributed to the slight covalent character.
So again, AlCl3 cannot be described as ionic, rather it is a covalent compound. So the right answer is MgCl2.

The reason for covalency in AlCl3 is the high charge density of Aluminum ion, and large electron cloud of chlorine atom. Aluminum fluoride, for example, is ionic, since fluorine electron clouds are not large enough to be polarised by aluminum ion.

Thankyou sooooo much!!

 

[nehaoscar]

it cant be option A or D .. and the only 2 choices are B and C ..
as u see ... Sulfuric acid is a dehydrating agent and there fore dehydrates Alcohol to alkene ...
And we also know that Alkenes reacts with Sulfuric acid therefore we purify them with dilute NaOH ie option C

What would be the products formed in each case?
Could you write the equations please?

 

[nehaoscar]

 

[nehaoscar]

 

[nehaoscar]

What would reaction 3 give?

 

[nehaoscar]

Why is C wrong? what's the bond angle of Cl2?

 

[Mathemagical]

Why is C wrong? what's the bond angle of Cl2?

They do not want the bond angle of Cl2, instead it is the bond angle of CH4 you should find. Since chloroethanes are formed, there is no change in the bond angle.

 

[Mathemagical]

What would reaction 3 give?

Reaction 3 would not occur because only carboxylic acids react with hydrogencarbonates.

 

[princess Anu]

Whats the answer

 

[♣♠ Magnanimous ♣♠]

Thanks alotttttttttt

 

[nehaoscar]

Whats the answer

It's A

 

[princess Anu]

shouldn't it be A?

 

[princess Anu]

why is it A ?:s why are other options wrong?

 

[Mathemagical]

View attachment 54541 shouldn't it be A?

It will not necessarily have structural isomers.