Chemistry: Post your doubts here!

[Metanoia]

View attachment 62667 I need help with this. From March 2017 Paper 4 I only get 6 different carbon environments

 

[i_try9621]

View attachment 62670

Isn't 6 and 7 the same?

 

[Metanoia]

Isn't 6 and 7 the same?

We should look beyond the immediate neighbors, 6 and 7 aren't exactly the same

The symmetry is at carbon 7, that is why 6 is the same as 6a and 5 is the same as 5a, but 7 is not the same as any of them



A simplified view of the molecule is shown before to hopefully explain the symmetry better, the symmetry is at carbon d.

 

[i_try9621]

We should look beyond the immediate neighbors, 6 and 7 aren't exactly the same

The symmetry is at carbon 7, that is why 6 is the same as 6a and 5 is the same as 5a, but 7 is not the same as any of them

View attachment 62671

A simplified view of the molecule is shown before to hopefully explain the symmetry better, the symmetry is at carbon d.

View attachment 62672

Thanks for the help, I understood it now.

 

[i_try9621]

Need help with i) and iii) from 42/M/J/16 . In i) The answer says "Asp having a charge of -2 and Val having a charge of -1" which I don't understand and in iii) The buffer pH is 12 but shouldn't it be pH 7 ?

 

[i_try9621]

Need help with c) iv). Why are there 2 different structures? How would I know if mine is right?

 

[Alpharaptor]

Any guesses for chemistry 33 retake oct/nov ????

 

[i_try9621]

Someone please explain this to me. My answer was
-> Peak at 1670-1740 due to C=O
-> Peak at 3200-3600 due to RO-H
-> Peak at 2850-2950 due to C-H in alkane

I picked these range of wavenumber from Data booklet but mark scheme shows a different answer. For RO-H group, the absorption is 3200-3650 but data booklet shows 3200-3600... How do i measure the exact absorption from the spectra?

I don't think you have to measure the exact spectra, your answer is right if you have taken your values from the Data Booklet.

 

[Parhaakoo]

Can anyone pls tell how to do this?

 

[i_try9621]

Can anyone pls tell how to do this?

Using the electrode potential you can figure out an equation this way. Follow the arrows and you eliminate the electrons giving one-way reaction

 

[i_try9621]

Anyone know how to solve this question. I am mainly having trouble with how they set up the equation. It's from 42/F/M/16.

 

[nerdybookworm]

anyone here gave wch01 edexcel AS chem yesterday????

 

[i_try9621]

Anyone gave CIE P3 practical yesterday?

 

[auxy12]

CAN ANYONE EXPLAIN HOW TO GET X AND Y?

 

[Bishnu Dev]

View attachment 62716
CAN ANYONE EXPLAIN HOW TO GET X AND Y?

First find out the volume of CO2 which is formed by the combustion....
volume of CO2 = 170-110 = 60 cm3

X = volume of CO2 / Volume of Alcohol
X = 60 / 20 = 3

Now find volume of water
Volume of Water = 250 - 170 = 80 cm3
Y / 2 = Volume of H2O / Volume of Alcohol
Y / 2 = 80 / 20 = 4
So Y = 8

 

[i_try9621]

Anyone please help me with V and W ? Shouldn't Oxygen be replace with O-H bond ?

 

[i_try9621]

Someone help me with this please? I have a problem with understanding what test 1 and test 5 is for . Also which test is for Amine and Amide here?

 

[Thought blocker]

Anyone please help me with V and W ? Shouldn't Oxygen be replace with O-H bond ? View attachment 62717 View attachment 62718

but y?

 

[i_try9621]

but y?

I mean from C=O bond to C-OH bond or Am I wrong?

 

[i_try9621]

but y?

I think I found my mistake in there . Just to clarify, this is reduction of Amide to Amine yes?