Chemistry: Post your doubts here!

[asadalam]

The 3rd reaction doesn't involve D2O ... it is just the reaction between (Ammonium salt) NDH3Cl + (alkali) NaOD ... so we have only 2 D atoms now, but we actually need 3 D atoms to produce ND3 ...
so probably sth like ND2H or sth is produced instead, but that doesn't matter.

What do you mean?Then how is 2 correct?

 

[muhammadali233]

What do you mean?Then how is 2 correct?

nai aya ga yah ,itni fikar kyn kartay ho? ik din phele pharana tha? soo jao

 

[awesomaholic101]

What do you mean?Then how is 2 correct?

2 is correct coz water (D2O here) is involved in the alkaline hydrolisis of nitrile

 

[asadalam]

2 is correct coz water (D2O here) is involved in the alkaline hydrolisis of nitrile

Theres alkaline Hydrolysis of nitrile too?How many other groups are able to by hydrolysed by water/naoh/hcl

 

[awesomaholic101]

Theres alkaline Hydrolysis of nitrile too?How many other groups are able to by hydrolysed by water/naoh/hcl

Apparently, there is. God knows! urgh paper 1 is annoying ...

 

[asadalam]

Apparently, there is. God knows! urgh paper 1 is annoying ...

Any other thing that might seem more obscure yet can be asked?

 

[princess Anu]

which year is this from?

Which mixtures, on heating, produce the gas ND3?
[D = H 2
1 , an isotope of hydrogen]
1 CaO(s) and ND4Cl(s)
2 CH3CN and NaOD in D2O
3 NDH3Cl and NaOD in D2O

So D is like H so we can suppose NDH3Cl as NH4Cl so wouldnt reaction 3 also liberate ammonia?The Ms says only 1,2 are correct.

 

[awesomaholic101]

Any other thing that might seem more obscure yet can be asked?

I honestly have no idea ... examiners have twisted brains! genius, yes, but twisted.

 

[asadalam]

which year is this from?

W07

I honestly have no idea ... examiners have twisted brains! genius, yes, but twisted.

Amen to that.

 

[asadalam]

I honestly have no idea ... examiners have twisted brains! genius, yes, but twisted.

Can you explain these:
40 Fats and grease that build up on pans used in cooking are esters. Pans which are dirty from fats
or grease may be cleaned by heating them with a reagent that will react with the ester group.
What may be used to clean such pans by this reaction?
1 vinegar - aqueous ethanoic acid, CH3CO2H
2 alcohol - ethanol, C2H5OH
3 baking powder - sodium hydrogencarbonate, NaHCO3

 

[The Sarcastic Retard]

If you can find them,post the links...

You just can do that yourself... go few pages back..

 

[Studydayandnight]

The products obtained by cracking an alkane, X, are methane, ethene and propene. The mole fraction of ethene in the products is 0.5. What is the identity of X?

A C6H14
B C8H18
C C9H20
D C11H24

Correct answer is B.

 

[shazmina]

http://onlineexamhelp.com/wp-content/uploads/2014/08/9701_s14_qp_11.pdf
Question 3.......Help please!!!!!!!! The Ans is D
My doubt is why cant the answer be C????

 

[The Sarcastic Retard]

The products obtained by cracking an alkane, X, are methane, ethene and propene. The mole fraction of ethene in the products is 0.5. What is the identity of X?

A C6H14
B C8H18
C C9H20
D C11H24

Correct answer is B.

http://openstudy.com/updates/528895aee4b0b3376511f73a

 

[The Sarcastic Retard]

http://onlineexamhelp.com/wp-content/uploads/2014/08/9701_s14_qp_11.pdf
Question 3.......Help please!!!!!!!! The Ans is D
My doubt is why cant the answer be C????

Why u think C to be correct choice?

 

[qwertypoiu]

Thanks.

 

[The Sarcastic Retard]

View attachment 54871

View attachment 54872

Thanks.

 

[Tasneem_m98]

Please help! O/N 2005 p1 question 12

One mole of magnesium, aluminium, and sulphur are each completely burnt in an excess of oxygen gas. Which graph shows the moles of oxygen used in each case?
Answer is D but when i worked the equations out, I got
Mg + 1/2 O2 -> MgO
Al + 3/4 O2 -> 1/2 Al2O3
S + O2 -> SO2

And i noticed that there is a difference of 0.25 between each so i assumed it's a direct proportion hence my answer was A ( a lineat graph). However the answer is D. Please help!

 

[qwertypoiu]

Lol thank you
I've found answers now for those interested:
Calcium flame = brick red
Strontium flame = scarlet red
Barium flame = apple green.

And 2,4-DNPH makes a precipitate without the need of warming,
Whereas Tollen's and Fehling's solution require warming of mixture for results.

 

[manya]

(65 x 3 + 63 x 7) / 10 you divide by the total abundance, not 100

In your working, you should have wrongly used 100 as the dominator rather than 10.

oh okay thankyou so much