Chemistry: Post your doubts here!

[Tom Sewage]

Is it reactants - products OR products - reactants ? PLEASE REPLY ASAP I HAVE AN EXAM IN LESS THAN 4 HOURS !

For combustion it is reaction - product
for formation it is product - reaction

 

[IwanttopassAlevel]

anyone did p22?

 

[IwanttopassAlevel]

any tips for those of us writing p21??

 

[IwanttopassAlevel]

anybody...................no.........................

 

[LonelyStudent]

Here’s a good question. When they ask us to draw the structure of any molecule, should we ALWAYS draw its skeletal structure?

 

[IwanttopassAlevel]

they specify the structure

 

[LonelyStudent]

they specify the structure

If they don’t?

 

[A*****]

Wasn't the paper so damn easy today?? I expect the thresholds to be really high

 

[A*****]

If they don’t?

We can draw any of them

 

[aloo Kha]

paper 22 might have been the easiest paper in history
completed in less than 25 minutes

 

[Tauqir_hamed]

Does anyone remember the bronsted lowry acid question ? What did it actually say? Will this equation work : NH4+ + OH- > NH3 + H2O ,.

 

[Kanekii]

Does anyone remember the bronsted lowry acid question ? What did it actually say? Will this equation work : NH4+ + OH- > NH3 + H2O ,.

I think if i remember correctly it was about weak acids brownsted theory for it i wrote:
Acids whose H+ ions dissociate incompletly in aqueous solution. Is it right?
And for equation: NH4 + H20= NH4OH + 0.5H2

 

[abbas haider]

I think if i remember correctly it was about weak acids brownsted theory for it i wrote:
Acids whose H+ ions dissociate incompletly in aqueous solution. Is it right?
And for equation: NH4 + H20= NH4OH + 0.5H2

no
you have wrote the definition of a weak arehenius acid
arhenius acid = a substance that dissolves in water to form H+ ions
bronsted lowery acid = proton doner (these acids can exist in any state not only aqueous)

anyways the definiton should have been

A weak bronsted lowery acid is one which partially donates proton.

 

[Kanekii]

no
you have wrote the definition of a weak arehenius acid
arhenius acid = a substance that dissolves in water to form H+ ions
bronsted lowery acid = proton doner (these acids can exist in any state not only aqueous)

anyways the definiton should have been

A weak bronsted lowery acid is one which partially donates proton.

But H+ ions are protons but i guess you're right about existing in any state

 

[abbas haider]

I think if i remember correctly it was about weak acids brownsted theory for it i wrote:
Acids whose H+ ions dissociate incompletly in aqueous solution. Is it right?
And for equation: NH4 + H20= NH4OH + 0.5H2

Check this reaction amonia is acting as an acid even though its a gas....arhenius theory(what you leant in o levels) can t explain this
Thats why In A levels They taught you Bronsted Lowery Theory of Acids..

 

[Tauqir_hamed]

abbas haider could you tell me whether that equation will work or not? ( the one that I have written above i.e. NH4 + + OH- --> NH3 + H2O. ) Did todays question specifically ask to show between NH4+ and H2O.. could you please tell me.. I am talking about varient 22

 

[A*****]

Wasn't the equation:
NH4+ —› NH3 + H+ ??

 

[Fardeen3342]

can someone help with this I don't get the concept behind it

 

[{#}324354]

What if I wrote lithium tetrahydridoborate instead of lithium tetrahydroborate?? Would I get the mark?

And on page 9, the answer was optical isomerism?

 

[Holmes]

If they don’t?

It's better that you draw a skeletal structure (AS chem)