Chemistry: Post your doubts here!

[Abdel Moniem]

Please help me on the reaction of ethanal and propanal. Like what happens? A question was in M/J/09 paper 2
The explaination is given here - http://research.cm.utexas.edu/nbauld/teach/ch610bnotes/ch18/crossaldol.htm
BUT HOW??

Question Number?

 

[Sasuke Uchiha]

Anybody have tips or hints on the pratical paper (Paper 3)?

 

[Sasuke Uchiha]

Could someone please tell me where is the discussion of paper 3?

 

[Muskan Achhpilia]

Hi can anyone please help me with the following questions-


The answer is B, if possible can someone please highlight the chiral centres cause i thought it should be C


The answer is D, i don't get this one at all.


The answer is B though I thought it can equally be A or B.


The answer is C


The answer is B


The answer is C, that is option 2 and 3 is correct.


The answer is D

Thank you so much for your effort and time!

 

[shaheerrn]

can someone make a marking scheme for this

 

[Thought blocker]

♣♠ Magnanimous ♣♠ Do help this buddies. This is your subject. Why are you not helping?

 

[♣♠ Magnanimous ♣♠]

♣♠ Magnanimous ♣♠ Do help this buddies. This is your subject. Why are you not helping?

okay but some of them idk so i am not answering

 

[Thought blocker]

okay but some of them idk so i am not answering

Answer those in which you are confident, and in which you aren't, just write that, please wait for others to answer.

 

[♣♠ Magnanimous ♣♠]

Answer those in which you are confident, and in which you aren't, just write that, please wait for others to answer.

okay

 

[Thought blocker]

okay

Start.

 

[♣♠ Magnanimous ♣♠]

Start.

right now i am going but till night i will do it for sure.

 

[Thought blocker]

right now i am going but till night i will do it for sure.

Of course, solve it when ever you are free.

 

[Rockstar RK]

Somebody pl suggest me that will i have to mug up the ph ranges for different indicators or not... And will i have to remember the end points of them???

 

[Abdel Moniem]

i answered question paper 21 June 2014 chemistry AS

 

[AnujaK]

Heeyy everyone! I've started a site that'll give you SOLVED past papers! Really helpful! Do check it out Also has some worksheets and revision notes!
https://sites.google.com/site/fromatoscom/

 

[M.Shahzaib Shoaib]

Does anyone have notes for *Electrode Potential* chapter?

The chapter in my text book contains too much extra information.

 

[♣♠ Magnanimous ♣♠]

Hi can anyone please help me with the following questions-
View attachment 46260

The answer is B, if possible can someone please highlight the chiral centres cause i thought it should be C

View attachment 46261
The answer is D, i don't get this one at all.

View attachment 46262
The answer is B though I thought it can equally be A or B.

View attachment 46264
The answer is C

View attachment 46265
The answer is B

View attachment 46267
The answer is C, that is option 2 and 3 is correct.

View attachment 46268
The answer is D

Thank you so much for your effort and time!

Hello it's Magnanimous here and I am really sorry for solving your doubt so late.
Umm, I am gonna start with 9 as I am very poor in Organic Chemistry.


20) I am getting only four isomers of C3H4Cl2.

9) As you will be knowing that HCl is STRONG ACID so for a simple logic the answer will be stong acid too..
So Sodium Hydroxide will be eliminated coz it is a base. For Ethanoic acid it is a weak acid. For sulphuric acid it is more strong acid than HCl so it will produce more concentration og hydrogen ion (maybe) So left is Nitric acid and it is the answer coz HCl and HNO3, when dissolved in water (having same normality) produces same number of H+ ions.

1)
See here Ur is --> Unreacted Oxygen.
I hope you got the calculations which i have done here. Overall I have shown the conversion of volume from Cm3 to dm3 and it's respective ratio.
The ratio is 1:5:3 which means now i can solve the equation by the volume ratio and now let's take this ratios as their moles which means :

1 mole of Hydrocarbon (CxHy)
5 mole of Oxygen (O2)
and 3 mole of Carbon Dioxide (CO2) Now let's make the equation with moles :

1CxHy + 5O2 -----> 3CO2 + H2O

Now if you know balancing the equation you will get :
1C3H8 + 5O2 ----> 3CO2 + 4H2O
So hydrocarbon is C3H8

 

[♣♠ Magnanimous ♣♠]

Hi can anyone please help me with the following questions-
View attachment 46260

The answer is B, if possible can someone please highlight the chiral centres cause i thought it should be C

View attachment 46261
The answer is D, i don't get this one at all.

View attachment 46262
The answer is B though I thought it can equally be A or B.

View attachment 46264
The answer is C

View attachment 46265
The answer is B

View attachment 46267
The answer is C, that is option 2 and 3 is correct.

View attachment 46268
The answer is D

Thank you so much for your effort and time!

Continuations

2) For this just refer this site which also contain example of Cl+2
Here you go : http://www.chemguide.co.uk/analysis/masspec/elements.html

31) C2H5OH + 3.5O2 --> 2CO2 + 3H2O
So now for Combustion of Ethanol you don't get 2.5 moles of Oxygen so obviously other two answer will be correct and you can check it too. ( I have not done but just by a logic I got the answer).

8) sorry Idk this

I hope you got your doubts solved and if any quarries you can surely tell me

 

[Ericyong]

Naturally occuring silicon is a mixture of three isotopes, 28Si, 29Si, and 30Si. The relative atomic mass of silicon is 28.109. What could be the relative abundance of each of the three isotopes?

Help pls I can't figure it out

 

[♣♠ Magnanimous ♣♠]

Naturally occuring silicon is a mixture of three isotopes, 28Si, 29Si, and 30Si. The relative atomic mass of silicon is 28.109. What could be the relative abundance of each of the three isotopes?

Help pls I can't figure it out

where is this ques? can you tell me?