Chemistry: Post your doubts here!

[bumble26]

from W10 please help with question 35,15,4
from S09 please help with 12,13,20
please explain to me.

 

[Akshaya bhattarai]

HEY whats the logic behind liquid noble gases

 

[iKhaled]

but do you get why its 10

because they didn't just say the no of electrons in the outer shell, right? they meants the total no of electrons in the whole ion eh?

 

[Osake]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf

Can someone help me in question 8,11 please?.

 

[Akshaya bhattarai]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf

Can someone help me in question 8,11 please?.

please download and zoom it to see!

 

[saudha]

On collision, airbags in cars inflate rapidly due to the production of nitrogen.
The nitrogen is formed according to the following equations.
2NaN3 → 2Na + 3N2
10Na + 2KNO3 → K2O + 5Na2O + N2
How many moles of nitrogen gas are produced from 1 mol of sodium azide, NaN3?
A 1.5 B 1.6 C 3.2 D 4.0

 

[Osake]

please download and zoom it to see!

Thank you very much!

 

[nazzzzzz]

Dude manganate is purple! :/

Lolsorry got it confused with K2 Cr2 O7 for a sec. Thanks foR correcting me, now I'll remember that and try not to make it at the exam

 

[saudha]

i wish all the best to everyone

 

[samwickz]

good luck u guys im having d ppr in another 1hr

 

[MysteRyGiRl]

umm is there anybody there right now for rescue?

 

[Jaf]

^Yeah I still have a couple of hours in my exam. Fire away. I'll see what I can do.

 

[MysteRyGiRl]

yessss
I2+3Cl2---->2ICl3 -214
I2(s)---->I2(g) +38
What is the standard enthalpy change of formation of iodine trichloride?
A +176
B -88
C -176
D -214
i cant get B

 

[MysteRyGiRl]

which isomer forms 3 alkenes on dehydration?
A butan-1-ol
B butan-2-ol
C 2-methylpropan-1-ol
D 2-methylpropan-2-ol
its B bt i cnt get more than 2 alkenes.could u plz explain?

 

[MysteRyGiRl]

0.2 mol of a hydrocarbon undergo complete combustion 2 give 35.2 g of carbondioxide and 14.4 g of water as the only products.
what is the molecular formula of the hydrocarbon?
A C2H4
B C2H6
C C4H4
D C4H8
its C but how

 

[MysteRyGiRl]

ok i think the rescuer is no longer here...
plz help whoever comes and knows the answer

 

[Jaf]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w05_qp_1.pdf

Can someone pleas help me with question 24? PLEASE? I really don't have any idea what to do.. PLEASE guys.

The answer is A. Try drawing all the possible alkenes that can be formed.
Butan-2-ol will form but-1-ene and cis but-2-ene and trans but-2-ene.
Propan-1-ol can only form propene.
2-methylbutan-2-ol can not be turned into an alkene as the hydroxy group is attached to a tertiary carbon.
2-methylpropan-2-ol can also not be turned into an alkene for the same reason as above.

 

[Jaf]

yessss
I2+3Cl2---->2ICl3 -214
I2(s)---->I2(g) +38
What is the standard enthalpy change of formation of iodine trichloride?
A +176
B -88
C -176
D -214
i cant get B

You're missing important details of the question here. Please give the link of the original question.

 

[Jaf]

which isomer forms 3 alkenes on dehydration?
A butan-1-ol
B butan-2-ol
C 2-methylpropan-1-ol
D 2-methylpropan-2-ol
its B bt i cnt get more than 2 alkenes.could u plz explain?

For butan-2-ol, the possible alkenes are
but-1-ene
cis but-2-ene
trans but-2-ene

 

[MysteRyGiRl]

You're missing important details of the question here. Please give the link of the original question.

there isnt anything missing :s
its M/J 10 ques no.5