AS Chemistry Doubts

[TSZ]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w02_qp_1.pdf
okay, for now this is my last ppr in wich i have a problem....the questions are Q.8, Q.11

 

[TSZ]

Q13
Al is bonded to N and three Hydrogens: no lone pair hence tetrahedral!
Q18
The fertiliser is NH4NO3

How do u knw that it is NH4NO3?

 

[donorsolutions]

The question is in May/June 2003 Q2. Please I asked many people but they didnt know the answer. Question is attached

In that question, you can see that there are three side chains (arranged in rows), all having same structure, With 3 double bonds in each side chain.
Now question says one side chain is converted to a compound with 2 double bonds. This means that one double bond has been broken so a mole of hydrogen was used in the first chain. In the other two side chains the compound formed has only 1 double bond. This means that 2 double bonds, each from both side chains have been broken and therefore 2x2=4 double bonds broken meaning 4 moles of H2 have reacted with the two side chains and 1 mole with the first side chain, as shown above...so total moles of hydrogen reacted = 4+1...5 Moles
Hope that Helps

 

[1357913579]

Q8
Remember that moles and volume law along with the gas laws!
Volume =no of moles of gas * 24 dm^3
Same no of moles means the same pressure!
Again while solving keep the gas laws in mind, there are statements like "V/2"
Q11
Not gonna solve this here: not because I don't wan't to, but because it'll take up too much space! And you'll understand better!
I'll get you started:
Initial moles:
b,0,0
Equilibrium moles:
b-x,x/2,x/2
What is the expression for Kp?
You also need to calculate mole fractions(Kp)
Then simplify!

for number 11 as total moles in numerator and denomerator is same thats why we can use hte moles right as even if there was the total pressure it would have been cancelled out but we need the total pressure if total product and reactcant moles are different right??

 

[Paparazzi478]

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 D4.0

Can someone tell me how the answer is B?

 

[Paparazzi478]

Concentrated sulphuric acid is added to separate solid samples of sodium chloride, sodium
bromide or sodium iodide.
With which sample(s) does sulphuric acid act as an oxidising agent?
A sodium chloride only
B sodium chloride and sodium bromide
C sodium bromide and sodium iodide
D sodium iodide only

why doesnt h2so4 acts like and qxidizing agent with nacl?

 

[1357913579]

i have a doubt in mayjune 2007 number 34 paper-1
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s07_qp_1.pdf
thanks for helping

 

[1357913579]

please tell me why is the answer A and not B?

iam just confused like why does the activation energy increase is it because reaction will be endo so energy is required

 

[kkhizar1]

thanks

 

[1357913579]

You must follow the reaction pathway diagram in this one.
Imagine starting from the opposite side, change in enthalpy is positive and the activation energy in larger.

i dont get it like how does activation energy increase
ofcourse i do know enthalpy is positive
thanks for hepling

 

[iFuz]

Simple question,
Define Electrophile and Nucleophile... with examples..

 

[iFuz]

Simple answer,
Google it...

You cant do it, betta not reply! -.-
Let others do!

 

[Duamask]

Somebody Explain me how to find the chiral carbon atom :/
and why is Organic chem soo confusing, any methords to learn them in an easy way, MCQS SCAREE MEEE! :'(

 

[gary221]

Somebody Explain me how to find the chiral carbon atom :/
and why is Organic chem soo confusing, any methords to learn them in an easy way, MCQS SCAREE MEEE! :'(

A molecule which has no plane of symmetry is described aschiral. The carbon atom with the four different groups attached which causes this lack of symmetry is described as a chiral centre or as an asymmetric carbon atom.

 

[donorsolutions]

Please explain how is Question 39 done ?
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w08_qp_1.pdf

 

[smartangel]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s11_qp_11.pdf
please explain 15, 16 ,22..PLEASE!

 

[floral123]

The answer is 8...........
In order to identify the no of cistrans isomers u need to first identify the stereocentres.If a compound has a C-C double bond and each of the C in the double bond is bonded to seperate groups then the compound has a stereocentre.In the above case there are 3 such centres.The total number of cistrans isomers is given by the formula 2^n so 2^3=8. There you go......

is this formula correct??I mean i never studied this...from which book u read this??

 

[floral123]

X2H6 has a one X-X bond and 6 X-H bonds.The eqn given above is thatenthalpy change of formation meaning all these bonds were formed.......The energy released during bond formation is equal in magnitude but with a negative sign to the bond energy(coz its exothermic).........So we have 2775 = 6 * 395 +x .................Answer is 405

kindly explain that why not -405???
u said that bonds are formed so sign should be negative...

 

[raamish]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w10_qp_12.pdf

PLease explain qs 7 and 8 pllllz

 

[Ash1994]

0.200 mol of a hydrocarbon undergo complete combustion to give 35.2 g of carbon dioxide 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
HOW DO WE FIND THE Mr OF the HYDROCARBON?