Chemistry: Post your doubts here!

[amina1300]

Can Anyone Explain everything we need to know about Organic Analysis ( I-R Spectroscopy) for AS Level? or some links to where I could get the notes??
Or explain with some past exam question?

 

[amina1300]

Which reaction will give 2-chloropropane in the best yield?
A chlorine gas with propene gas in the presence of UV light
B cl2 gas with propene gas in the dark
C propan-2-ol with dil NaCl
D propan-2-ol with PCl5
The answer is D can anyone explain??

 

[amina1300]

31 The 1 H3 + ion was first characterised by J. J. Thomson over a century ago. 6 Li is a rare isotope of lithium which forms the 6 Li+ ion.
Which statements are correct?
1 Both ions contain the same number of protons.
2 Both ions contain the same number of electrons.
3Both ions contain the same number of neutrons.

ans is b explainnn

 

[shingiechingz@8]

can anyone give me some tips to excel in AS and A2 Organic Chemistry..............pleaseeeeee

 

[Thought blocker]

can anyone give me some tips to excel in AS and A2 Organic Chemistry..............pleaseeeeee

Take a piece of paper, jot down all formulas, conversions and neseccary things. Group them up orderly. REvise it again and again

 

[krishnapatelzz]

Take a piece of paper, jot down all formulas, conversions and neseccary things. Group them up orderly. REvise it again and again

and stick on the door of toilet

 

[Thought blocker]

and stick on the door of toilet

Forgot to mention xD

 

[Lee Qian Yi]

ok

CH3CH2CH2OH + 4.5O2------>3CO2 + 4H2O
so 0.1 mol propanol reacts with 0.45 mol of the o.5 mol oxygen provided (12dm3 oxygen is 0.5 mol)
0.05 mol of oxygen is left over as gas.
0.3 mol of CO2 is formed which is the gaseous product as H2O will be liquid at r.t.p.
0.35mol of total gases.
0.35x24=8.4dm3 gases in the final mixture under ROOM CONDITIONS.

ok thx

 

[wilson 98]

can anyone help me on question 19 of paper 13/ may june 2012?

 

[nadeen64]

Can someone please solve this question and solve it? c part ii nov 2016 paper 52

 

[krishnapatelzz]

Can someone please solve this question and solve it? c part ii nov 2016 paper 52
View attachment 61984
View attachment 61985

 

[darks]

pls explain all briefly. Starting from part (ii)
remember Ag2SO4 partially soluble.
paper is m/j 2015 p43
Thanks!!

 

[Ahmado Sherifo]

2-x : x/2 : x

In essence, it's a pretty simple question if you ask me. People tend to get confused seeing variables instead of constants.

Anyhow.

There are two approaches to this.

One is quicker but much more confusing. If you want, let me know and I'll enlist that too.

If not, simply take the equations and manipulate.

A- Inital: 2 : 0 : 0
Final : 2-x: 2x : x
Total moles: 2-2+2x+x = 3x so A is incorrect.

B-
Initial: 2 : 0 : 0
Final: 2-2x : 2x : x
Total moles: 2-2x+2x+x = 2+x so B is incorrect

C-
Initial: 2 : 0 : 0
Final 2-2x:x:x
Total = 2-2x+x+x = 2

D-
Initial: 2 : 0 : 0
Final: 2-x : x/2 : x [x = 2R]
Total moles = 2-x+x/2+x =2+x/2 mols!

B is correct cuz the ans is 2+x...

 

[student2]

ny1 knws hw 2 plan experiment fr solubility in p5?????

 

[darks]

View attachment 62015
pls explain all briefly. Starting from part (ii)
remember Ag2SO4 partially soluble.
paper is m/j 2015 p43
Thanks!!

help pleaseeeeee!

 

[msucurt]

Could someone please help me with a problem on May/June 2014/P23...question #2
I am having difficulty understand (iv). It says, "Calculate the amount, in moles, of ammonium ions in the sample of the double salt'. From what I see on the marking scheme, it is saying the NH4+ react with the H+ in a 1:1 ration. I dont understand where this 1:1 ration is coming from? The only equation that is written is
NH4+ + OH- -----> NH3 + H2O

thanks

 

[Laveeza]

Could someone please help me with a problem on May/June 2014/P23...question #2
I am having difficulty understand (iv). It says, "Calculate the amount, in moles, of ammonium ions in the sample of the double salt'. From what I see on the marking scheme, it is saying the NH4+ react with the H+ in a 1:1 ration. I dont understand where this 1:1 ration is coming from? The only equation that is written is
NH4+ + OH- -----> NH3 + H2O

thanks

 

[Lee Qian Yi]

Apply alcohol may also be converted into propanol by using a ruthenium (IV) catalyst in water.
CH2=CHCH2OH-> CH3CH2CHO
Suggest what is unusual about this single step ?
ANS : DISPROPORTINATION HAS TAKEN PLACE
How can I know that ? Anyone can explain?

 

[Laveeza]

Apply alcohol may also be converted into propanol by using a ruthenium (IV) catalyst in water.
CH2=CHCH2OH-> CH3CH2CHO
Suggest what is unusual about this single step ?
ANS : DISPROPORTINATION HAS TAKEN PLACE
How can I know that ? Anyone can explain?

Because the double bond is reduced and the alcohol group has been oxidised hence the compound has been oxidised and reduced at the same time .

 

[student2]

cn any1 just tell me hw H & J r not the same???