Chemistry: Post your doubts here!

[Lola_sweet]

What are the standard conditions for enthalapy changes? (Especially presssure)

Can someone explain how exothermic is bond making and endothermic is bond breaking?

 

[The Sarcastic Retard]

What are the standard conditions for enthalapy changes? (Especially presssure)

Can someone explain how exothermic is bond making and endothermic is bond breaking?

According to me, its just standared states that we need to keep in mind...
and pressure is I guess 1 atm = 101kpa

BEND FEXO! Remember this.

We are giving energy to break bond hence endo
When bond is formed heat is released so exo...

 

[ahmedish]

As an A2 student, should I study new additions to the AS syllabus? My friend has the new book and I'll photocopy it, so I don't know if i should photocopy the entire book or just the A2 bit

 

[ruby_fern]

As an A2 student, should I study new additions to the AS syllabus? My friend has the new book and I'll photocopy it, so I don't know if i should photocopy the entire book or just the A2 bit

you need the AS part also as there are many questions from AS in paper 4, especially from organic chemistry

 

[nehaoscar]

could you explain 2(b)(iv) also from that paper?

When I solve it then In sha Allah.
nehaoscar have you done this?

Yep ... just use the rate equation you found out in the previous answer
so rate = k[CH3CHO][CH3OH][H+]
Substitute the values from either of the 4 equations to find the value of k
and then find rate = k * 0.2^3

 

[nehaoscar]

As an A2 student, should I study new additions to the AS syllabus? My friend has the new book and I'll photocopy it, so I don't know if i should photocopy the entire book or just the A2 bit

Just get the A2 bit (most which is repeated from the old book) - transition elements has additions in A2 chapter and infra-red spectroscopy from AS
There are not many other major changes needed for A2 so you don't need to get the whole book

 

[Lola_sweet]

According to me, its just standared states that we need to keep in mind...
and pressure is I guess 1 atm = 101kpa

BEND FEXO! Remember this.

We are giving energy to break bond hence endo
When bond is formed heat is released so exo...

101?

Omg thank you so much
i finally understand that

 

[The Sarcastic Retard]

101?

Omg thank you so much
i finally understand that

1atm = 101kpa

 

[ahmedish]

Just get the A2 bit (most which is repeated from the old book) - transition elements has additions in A2 chapter and infra-red spectroscopy from AS
There are not many other major changes needed for A2 so you don't need to get the whole book

I am 100% getting the A2 part, not sure if I should get the AS part as well. Will I need to study the new additions to the AS syllabus, if they exist?

 

[a_wiserME!!]

will anyone be able to draw the diagram and post it pls?? TIA

 

[a_wiserME!!]

how do i answer this?? the aluminuim hydroxide part :/
what the ms states : zinc (tetra) ammine (ions) (aluminium hydroxide) for step 2 substances at the end

 

[Ruman Wajih]

got a d in as physics. if i work extremely hard in A2 can my d turn into a b ?

 

[nehaoscar]

I am 100% getting the A2 part, not sure if I should get the AS part as well. Will I need to study the new additions to the AS syllabus, if they exist?

Not really... AS the organic part there are no changes and the only extra thing you need to know from AS is the infra-red spectroscopy

 

[a_wiserME!!]

NotYourType

 

[nehaoscar]

Complete revision notes for A2 Chemistry on here:
https://www.xtremepapers.com/community/threads/a2-chemistry-revision-notes.42748/
For more revision notes check out my signature below
Make sure to hit that like button

 

[Asim Shah]

got a d in as physics. if i work extremely hard in A2 can my d turn into a b ?

Yes sure

 

[a_wiserME!!]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s13_qp_52.pdf

can someone pls explain the first ques how to do the dilution of the HCl??
TIA

 

[DESTROYER1198]

It's on here:
http://papers.gceguide.com/A Levels/Chemistry (9701)/9701_w15_gt.pdf

Thanks mate

 

[i_try9621]

Anyone knows what volume strength means ?
it's from 9701/31/M/J/14
Queston 1

 

[Rizwan Javed]

It is already defined in the question. Volume strength is the volume of O2 evolved at rtp when a certain volume of H2O2 is completely decomposed. Like if 20dm^3 of O2 is evolved from a 1 dm^3 Volume of H2O2 on decomposition, then the volume strength of H2O2 is 20 vol. Similarly if Volume of O2 evolved will be 35dm^3 from 1dm^3 H2O2 then Volume strength will 35 vol.

In more easy words, it is the volume of O2 evolved per unit volume decompostion of H2O2.