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Chemistry: Post your doubts here!

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ahmedish

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nehaoscar said:
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
Click to expand...
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!!

a_wiserME!!

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upload_2016-1-22_22-24-53.png


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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
 

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nehaoscar

nehaoscar

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ahmedish said:
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?
Click to expand...
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
 
Rizwan Javed

Rizwan Javed

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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.
 
Eugene99

Eugene99

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Why is the bond angle in a typical tetrahedral molecule 109.5 degree but not 90? Cuz for a trigonal molecule, a single bond angle is calculated to be 360/3 = 120 but how is 109.5 calculated logically if I wouldn't like to learn it.
 
nehaoscar

nehaoscar

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upload_2016-1-12_20-8-47-png.58809

How is the mechanism nucleophilic substitution?
The CH3-CH2 attaches to the NH removing HBr, and the CH2 has a positive delta... so wouldn't it be electrophilic...
Please explain why it's nucleophilic :/
 
Konstantino Nikolas

Konstantino Nikolas

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nehaoscar said:
upload_2016-1-12_20-8-47-png.58809

How is the mechanism nucleophilic substitution?
The CH3-CH2 attaches to the NH removing HBr, and the CH2 has a positive delta... so wouldn't it be electrophilic...
Please explain why it's nucleophilic :/
Click to expand...
I guess we need to consider the acid attacking bromoethane. In that case, the lone pair on the Nitrogen atom would make the acid a nucleophile ... thus nucleophilic substitution.
Just an idea though, I'm not sure.
 
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