Chemistry: Post your doubts here!

[The Sarcastic Retard]

Can anyone plz explain me in detail about the differences b/w
1. covalent bonding
2. ionic bonding
3.hydrogen bonding ( and how and why hydrogen bonds are formed) ?

Help will be appreciated.

Covalent bonding : sharing of electrons; simple molecular structure has low melting and boiling point and bonded with either weak vaan der waals force (co2)or induced dipole induce dipole (I2) giant molecular structures have high mp n bp (sio2, diamond, graphite); cannot conduct electricity except graphite in which one electron is free to carry current.
Ionic bonding: transfer of electrons; all have high mp n bp; can conduct wlectricity in molten state.
Hydrogen bonding : when hydrogen is bonded with very highly electronegative element like F,N,O

 

[Awesome12]

Could someone please explain this? (Answer is B)



​

 

[Bilal Khan]

How to find NMR environments of any organic compound?

 

[Bilal Khan]

Like for Pentanal , how many will it be?

 

[Maayee]

is that paper 31?

yup that was paper 31

 

[9aliasad]

Hi everyone, AsSalamoAlaikum Wr Wb..

To get things organized in a better way, I am making this thread. As othewise, some queries remain unanswered!

So post your CHEMISTRY doubts in this thread. InshaAllah members around will help you.

Any Chemistry related notes and links will be added here in this post. Feel free to provide the links to your notes around the forum, or any other websites!

Chemistry Notes:


http://www.chemguide.co.uk This is the website, which contains almost everything classified according to the syllabus.

Tips for solving chemistry MCQs 9701/01

Chemistry P5 Tips and Notes

Some links & Notes - by 'destined007'

Chemistry worksheets Link shared by hassam

Chemistry Application Booklet: Mistakes and Corrections!

Calculations for A level Chemistry, author E.N. Ramsden third edition ebook download.


Regards,
XPC Staff.

Hello!
I am a private candidate of As Levels. Can anyone please help me by giving the instructions of Chemistry Practical 34 of May/June 2015?
Plzz help.

 

[Abdel Moniem]

yup that was paper 31

i also took paper 31 my highest temperature recorded in the 9th minute of experiment 2 was 34. I am not sure about this because all who took the same paper in my school reached to values 46 and 50. any idea whose correct?

 

[liptonice]

i also took paper 31 my highest temperature recorded in the 9th minute of experiment 2 was 34. I am not sure about this because all who took the same paper in my school reached to values 46 and 50. any idea whose correct?

Im not sure tbh, I did the paper and the experiment was exothermic, and the idea was that at the start of 3 minutes it would increase and then as time goes by, the temperature decreases, like I started with 45 then it was 50, highest was 57 then it decreased, to about 30-40 cant remember sorry but it should be correct, Btw the titration did you get 29.98 cm ?

 

[Abdel Moniem]

Im not sure tbh, I did the paper and the experiment was exothermic, and the idea was that at the start of 3 minutes it would increase and then as time goes by, the temperature decreases, like I started with 45 then it was 50, highest was 57 then it decreased, to about 30-40 cant remember sorry but it should be correct, Btw the titration did you get 29.98 cm ?

i started with a temperature of 23 degrees at t=0 and one i added the zinc temperature increased till i reached to the 9th minute where the temperature was 34 degree's. i got my titration rough volume as 29.5 cm^3 and the other two trials were 29.3 and 29.4 cm^3.

 

[Abdel Moniem]

Im not sure tbh, I did the paper and the experiment was exothermic, and the idea was that at the start of 3 minutes it would increase and then as time goes by, the temperature decreases, like I started with 45 then it was 50, highest was 57 then it decreased, to about 30-40 cant remember sorry but it should be correct, Btw the titration did you get 29.98 cm ?

i think you cant get your volume to 2 d.p it should be either a 30.0 cm^ if your botom of meniscus was more to the 30 than to the 29.9

 

[anonymous1122]

Bromine has 1:1 ratio of m and m+2
Chlorine has 1:3 ratio

how to find the other element

View attachment 53315

 

[liptonice]

i started with a temperature of 23 degrees at t=0 and one i added the zinc temperature increased till i reached to the 9th minute where the temperature was 34 degree's. i got my titration rough volume as 29.5 cm^3 and the other two trials were 29.3 and 29.4 cm^3.

And what was the FA6 ? So4 and ?

 

[Abdel Moniem]

And what was the FA6 ? So4 and ?

i said it was copper and sulphate, i asked my teacher he said it should be a carbonate not a sulphate.

 

[Maayee]

i also took paper 31 my highest temperature recorded in the 9th minute of experiment 2 was 34. I am not sure about this because all who took the same paper in my school reached to values 46 and 50. any idea whose correct?

i asked my cousin and her highest temperature was 56

 

[Abdel Moniem]

i asked my cousin and her highest temperature was 56

lol, looks like i will fail this test. I think the reagents given to me were not well prepared.

 

[Maayee]

lol, looks like i will fail this test. I think the reagents given to me were not well prepared.

dont worry, there's still paper 1 left... do well in that and insha allah u will get an A

 

[Abdel Moniem]

dont worry, there's still paper 1 left... do well in that and insh allah u will get an A

inshallah you too , i did well on paper 21, i have no problems with any of the theory papers but my main problem here is paper 31. Do you know how many marks will i loose if both my titration and temperature values are incorrect?.

 

[Maayee]

inshallah you too , i did well on paper 21, i have no problems with any of the theory papers but my main problem here is paper 31. Do you know how many marks will i loose if both my titration and temperature values are incorrect?.

as long as your calculations are correct, u won't lose all the marks, u will probably lose 3 marks for accuracy

 

[Abdel Moniem]

as long as your calculations are correct, u won't lose all the marks, u will probably lose 3 marks for accuracy

Thank' you got my hopes up.That's the only thing i am sure of calculation and the data representation(table and rounding of value's).

 

[Maayee]

That's the only thing i am sure of calculation and the data representation(table and rounding of value's).

then u wont probably lose sooo much marks