Chemistry: Post your doubts here!

[smartangel]

agree wid ya he means but-1-ene and but-2-ene

I think he meant but-1-ene and but-2-ene.

guys..meanwhile he's looking for an image can u help me out with these two! theyre difficult! :/ http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf Q8 n 13 please!!

 

[donor]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s11_qp_12.pdf

please can anyone solve Q.26

 

[TheMan123]

another image please.!

oops yeah i meant but- not pent-
sorry! im finding one now

 

[TheMan123]

another image please.!

The first 3 images is what you are looking for
http://en.wikipedia.org/wiki/Butene

 

[smartangel]

A triple bond consists of one π bond and two σ bonds...is this statement true or false?

 

[smartangel]

The first 3 images is what you are looking for
http://en.wikipedia.org/wiki/Butene

thank you so much bro! im so glad you took out so much time to help me out

 

[KurayamiKimmi]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w08_qp_1.pdf
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w08_ms_1.pdf
^_^ Can anyone please tell me how to get the answers to question no 2, 4 ,14 ,30 and 38 please ?

 

[donor]

guys..meanwhile he's looking for an image can u help me out with these two! theyre difficult! :/http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf Q8 n 13 please!!

answer for 8 is D
atomisation energy+first ionisation energy+ second ionisation energy + enthalphy change of hydration
177+590+1150-1565=352


answer fo 13 is B
have to use trial and error method, that is try putting all options

 

[Muhammad Asif]

guys..meanwhile he's looking for an image can u help me out with these two! theyre difficult! :/ http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf Q8 n 13 please!!

Q8
sum of anti clockwise energy is equal to clock wise energy

thus H=177+11740-1565=+352

 

[furry.panda]

in such reactions the formula is P1V1+P2V2=P3V3
(2*1)+(1*2)=P3*3 -----------> 4k=P3(3)------>P3=4k/3

Thankyouuu! before i didnt know that formula exist ;p
and p1 is tmorrow! im going kraziiih

 

[Oliveme]

help with question 11 please. http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w06_qp_1.pdf
Can someone pls answer this? second time I'm posting.

 

[Zsiddiqui]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_qp_1.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_ms_1.pdf
^_^ Can anyone please tell me how to get the answers to question no 2, 4 ,14 ,30 and 38 please ?

Q2) First of all, we know CS2 is the limiting reactant
So 10 cm3 CS2 needs 30 cm3 O2 (See molar ratio)
That means 50 - 30 = 20 cm3 O2 is left after the reaction
Further,
10 cm3 CO2 and 20 cm3 SO2 are produced (See molar ratio)
So total volume of gases left after burning = 20 cm3 O2 + 10 cm3 CO2 + 20 cm3 SO2 = 50 cm3

The answer must be either C or D

Adding NaOH will neutralise (or remove) acidic gases
It will remove 10 cm3 CO2 and 20 cm3 SO2 = 30 cm3 acidic gases
Gas left after NaOH is added = 50 - 30 = 20 cm3

So, C is correct!

Q4) you have add the atomic number of hydrogen carbonate (HCO3-)
H= 1, C=6, O=8
So number of electron of anion = 1+6+(8*3)+1 = 32
The extra 1 is because the anion has a one extra electron that's the reason it has an overall charge of -1 so you have to add that too.
Option C is correct

Q14)

 

[Student12]

A triple bond consists of one π bond and two σ bonds...is this statement true or false?

Its false.. a triple bond has 1 sigma bond and 2 pi bond.

 

[Casablanca]

Its false.. a triple bond has 1 sigma bond and 2 pi bond.

Really? Wouldn't that mean it has 5 bonds then? Because one pi bond has 2 bonds, so 2 pi bonds... That's 4 bonds already. Then a sigma on TOP of that? Or am I making a mistake somewhere?

 

[Oliveme]

Please answer questions 22, 24, and 34. Thank you very much.

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w09_qp_12.pdf

 

[donor]

help with question 11 please. http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w06_qp_1.pdf
Can someone pls answer this? second time I'm posting.

 

[Muhammad Bin Tahir]

What is a dimer?

 

[Vui Loong]

http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_w06_qp_1.pdf No 9
http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_s05_qp_1.pdf No 7
Anyone please explain me to this?

 

[smartangel]

answer for 8 is D
atomisation energy+first ionisation energy+ second ionisation energy + enthalphy change of hydration
177+590+1150-1565=352


answer fo 13 is B
have to use trial and error method, that is try putting all options

umm but it sayd use oxidation numbers for 13.so im sure there is a way other than trial n error

 

[saudha]

The standard enthalpy changes of formation of iron(II) oxide, FeO(s), and aluminium oxide,
Al2O3(s), are –266kJmol–1 and –1676kJmol–1 respectively.
What is the enthalpy change under standard conditions for the following reaction?
3FeO(s) + 2Al(s)
3Fe(s) + Al 2O3(s)
A +878kJ B –878kJ C –1942kJ D –2474kJ

i get the opposite charges alwayss..... how do i get it right?