Chemistry: Post your doubts here!

[Konstantino Nikolas]

Yes I got it. Thank you so much. I really appreciate it
What if there were 6 C atoms in a ring, and one was bonded to CH3 and H? Is that C atom chiral?

No problem.
Only a 6 Carbon ring with nothing else attached? f that is the case, then it wouldn't be a chiral centre.

 

[Iris Dylan Lane]

Konstantino Nikolas already gave an excellent answer. I just wanna add one point.

To make it quick to find chiral carbons from a skeletal formula, you can find carbons from which at least 3 lines are coming out. The points (carbons) from which two lines are coming out (ie. The line just bent to form a vertex) must have 2 hydrogen atoms attached to it, so it could never be chiral. Furthermore, you should ignore any carbon attached to double bonds. This should help you find chiral centres quicker.

Of course, you still have to make sure there aren't two same groups attached to a carbon even if there are three lines coming out of it, like in the case of carbon number 9 in the above example.

Hahah okay..that's a really good point too. Thank you!

 

[Konstantino Nikolas]

Konstantino Nikolas already gave an excellent answer. I just wanna add one point.

To make it quick to find chiral carbons from a skeletal formula, you can find carbons from which at least 3 lines are coming out. The points (carbons) from which two lines are coming out (ie. The line just bent to form a vertex) must have 2 hydrogen atoms attached to it, so it could never be chiral. Furthermore, you should ignore any carbon attached to double bonds. This should help you find chiral centres quicker.

Of course, you still have to make sure there aren't two same groups attached to a carbon even if there are three lines coming out of it, like in the case of carbon number 9 in the above example.

Yupp. That comes with practice ... though it used to be difficult to comprehend the whole compound before knowing how to do it.

 

[Iris Dylan Lane]

No problem.
Only a 6 Carbon ring with nothing else attached? f that is the case, then it wouldn't be a chiral centre.

Yes nothing else. K..thanks

 

[Konstantino Nikolas]

Yes nothing else. K..thanks

Because it would be symmetrical if you split the compound. No problem.

 

[Iris Dylan Lane]

Because it would be symmetrical if you split the compound. No problem.

Stupid question, but could you tell me what's attached to that carbon atom other than the CH3 and H? Do you consider it to be the rest of the ring on both sides?

 

[Konstantino Nikolas]

Stupid question, but could you tell me what's attached to that carbon atom other than the CH3 and H? Do you consider it to be the rest of the ring on both sides?

Not stupid. It used to look like a maze to me before I figured out the entire thing and it became easy. Half the rest of the ring on either side.

 

[Iris Dylan Lane]

Not stupid. It used to look like a maze to me before I figured out the entire thing and it became easy. Half the rest of the ring on either side.

Isn't that going to be unsymmetrical? Three C atoms have to go on one side and two on to the other?

 

[Konstantino Nikolas]

Isn't that going to be unsymmetrical? Three C atoms have to go on one side and two on to the other?

I was kind of confused about that too. So i went the more mathematical way. Just drawing a line of symmetry. But it would be better if someone can explain it the chemistry way too.

 

[Iris Dylan Lane]

I was kind of confused about that too. So i went the more mathematical way. Just drawing a line of symmetry. But it would be better if someone can explain it the chemistry way too.

View attachment 59601

Hahah okay :') Ty for your time.

 

[Saad the Paki]

Since we're at it, why not help me with this?

 

[leenz98]

Is the answer B? ^

 

[Konstantino Nikolas]

Hahah okay :') Ty for your time.

xD np!

View attachment 59602
Since we're at it, why not help me with this?

Here you go:


The red Vs represent TWO hydrogen atoms bonded to the same Carbon atom. The red Os represent a double bond of a Carbon atom bonded to the neighboring group. So you can do this part mentally and eliminate all those Carbon atoms from the chiral list.

The yellow Os represent the chiral carbons. They are chiral because they are bonded to 4 different groups.

So the answer is C (7 chiral centres).

 

[drowning-in-studies]

How do you do Q 5 and 6?

 

[Lola_sweet]

How do you do Q 5 and 6?
View attachment 59613

Q5)
it cant be A as the protons and electrons are same in number.
it cant be B as the number of neutrons and electrons are same (remember chlorine is gaining an electron here)
it cant be C as the number of neutrons and protons are the same
its D because number of neutrons is 20, number of protons is 19 and number of electrons is 18 (K loses an electron)

for Q6) im gonna end up giving a crap explanation
so its best someone else explains it sorry abt tht :3

 

[drowning-in-studies]

A solution of Sn2+ ions will reduce an acidified solution of MnO4 – ions to Mn2+ ions. The Sn2+ ions are oxidised to Sn4+ ions in this reaction. How many moles of Mn2+ ions are formed when a solution containing 9.5 g of SnCl 2 (Mr: 190) is added to an excess of acidified KMnO4 solution?
A 0.010 B 0.020 C 0.050 D 0.125
Can someone pls help me with this??

 

[drowning-in-studies]

Q5)
it cant be A as the protons and electrons are same in number.
it cant be B as the number of neutrons and electrons are same (remember chlorine is gaining an electron here)
it cant be C as the number of neutrons and protons are the same
its D because number of neutrons is 20, number of protons is 19 and number of electrons is 18 (K loses an electron)

for Q6) im gonna end up giving a crap explanation
so its best someone else explains it sorry abt tht :3

Okay thanks

 

[drowning-in-studies]

Q5)
it cant be A as the protons and electrons are same in number.
it cant be B as the number of neutrons and electrons are same (remember chlorine is gaining an electron here)
it cant be C as the number of neutrons and protons are the same
its D because number of neutrons is 20, number of protons is 19 and number of electrons is 18 (K loses an electron)

for Q6) im gonna end up giving a crap explanation
so its best someone else explains it sorry abt tht :3

hehehe.. okay, Q 5 is very easy but sometimes i just freak out

 

[Lola_sweet]

hehehe.. okay, Q 5 is very easy but sometimes i just freak out

hahaha yeah it is easy but i feel the same way
sometimes the basic qs seem the most complicated ones xD but thats A-levels for you

 

[Dark Destination]

Does anyone have the latest revision guide that is according to the 2016 syllabus? Is it released?